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Nutrition

László, BabinszkyPéter, Bársony

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Nutritionírta László, Babinszky és Péter, Bársony

TÁMOP-4.1.2.A/1-11/1-2011-0009

University of Debrecen, Service Sciences Methodology Centre

Debrecen, 2013.


TartalomTárgymutató ......................................................................................................................................... 11. .......................................................................................................................................................... 2

1. 1. The role and importance of animal nutrition ...................................................................... 22. Challenges in the 21st century animal nutrition ..................................................................... 3

2.1. 2.1. The application of the latest scientific findings in pig nutrition and in innovation ........................................................................................................................................... 42.2. 2.2. Main research areas foreseen in animal nutrition ............................................... 4

2.2.1. 2.2.1. Molecular nutrition research ............................................................... 52.2.2. 2.2.2. Relationship between genetics and nutrition ....................................... 52.2.3. 2.2.3. Modeling (prediction) of animal production ....................................... 72.2.4. 2.2.4. “From farm to fork chain” integrated research and innovation programs .................................................................................................................................. 7

3. Test questions: ........................................................................................................................ 94. Recommended reading ........................................................................................................... 9

2. 1. CHEMICAL COMPOSITION OF FEEDSTUFFS ................................................................... 101. 1.1. COMPONENTS OF DIFFERENT FRACTIONS IN THE PROXIMATE ANALYSIS OF FEEDSTUFFS (WEENDE METHOD) ................................................................................... 102. 1.2. DETERMINATION OF NEUTRAL-DETERGENT FIBER (NDF) AND ACID-DETERGENT FIBER (ADF) (VAN SOEST-METHOD) ....................................................... 113. 1.3. NON-STARCH POLYSACCHARIDES (NSPS) ........................................................ 124. 1.4. NEAR INFRARED REFLECTANCE SPECTROSCOPY (NIRS) FOR THE ANALYSIS OF FEED ........................................................................................................................................ 135. Test questions: ...................................................................................................................... 146. Recommended reading ......................................................................................................... 14

3. 2. THE DIGESTIVE TRACT AND ITS FUNCTIONS ................................................................ 151. 2.1. DIGESTIVE CHARACTERISTICS OF FARM ANIMALS ....................................... 152. 2.2. FUNCTION OF THE DIGESTIVE SYSTEM OF MONOGASTRIC ANIMALS ...... 17

2.1. 2.2.1. Digestive characteristics of horse .................................................................. 182.2. 2.2.2. Digestive characteristics of the pig ................................................................ 182.3. 2.2.3. Digestive characteristics of rabbit ................................................................. 192.4. 2.2.4. Digestive characteristic of poultry ................................................................. 19

3. 2.3. FUNCTION OF THE DIGESTIVE SYSTEM RUMINANTS .................................... 204. 2.4. FUNCTION OF THE DIGESTIVE SYSTEM OF SUCKLING (YOUNG) ANIMALS 215. Test questions: ...................................................................................................................... 216. Recommended reading ......................................................................................................... 21

4. 3. THE METABOLISM OF NUTRIENTS IN MONOGASTRIC AND RUMINANT ANIMAL 231. 3.1. PROTEIN AND AMINO ACIDS ................................................................................. 23

1.1. 3.1.1. Chemical structure and properties of protein ................................................ 231.2. 3.1.2. Digestion of protein ....................................................................................... 241.3. 3.1.3. Classification of amino acids ......................................................................... 241.4. 3.1.4. Disorders in protein supply ........................................................................... 251.5. 3.1.5. Nutritive value of protein sources ................................................................. 261.6. 3.1.6. Protein efficiency ratio (PER) and net protein utilization (NPU) .................. 27

2. 3.2. LIPID (FATS) ................................................................................................................ 282.1. 3.2.1. Digestion of fats ............................................................................................. 322.2. 3.2.2. Rancidity of fats ............................................................................................. 32

3. 3.3. CARBOHYDRATES .................................................................................................... 343.1. 3.3.1. Nitrogen free extracts .................................................................................... 34


Nutrition

3.2. 3.3.2. Crude fiber ..................................................................................................... 384. 3.4. VITAMINS AND THEIR INTERACTIONS ............................................................... 45

4.1. 3.4.1. Vitamins in general ........................................................................................ 454.2. 3.4.2. Fat-soluble vitamins ..................................................................................... 464.3. 3.4.3. Water-soluble vitamins .................................................................................. 514.4. 3.4.4. Vitamin-like substances ................................................................................. 604.5. 3.4.5. Vitamin interactions ....................................................................................... 63

5. 3.5. MINERALS .................................................................................................................. 665.1. 3.5.1. Macroelements ............................................................................................... 685.2. 3.5.2. Microelements ............................................................................................... 69

5. 4. MEASUREMENT OF THE UTILIZATION OF THE PROTEINS/AMINO ACIDS AND ENERGY ............................................................................................................................................................ 72

1. 4.1. IN VIVO DIGESTIBILITY OF DIETARY PROTEIN AND AMINO ACIDS ............ 721.1. 4.1.1. Digestibility of amino acids in pigs ............................................................... 721.2. 4.1.2. Digestibility of amino acids in poultry .......................................................... 82

2. 4.2. IN VITRO DIGESTIBILITY OF DIETARY PROTEIN .............................................. 883. Test questions: ...................................................................................................................... 904. Recommended reading ......................................................................................................... 90

6. 5. ENERGY METABOLISM OF FARM ANIMALS ................................................................... 921. 5.1. ENERGY TERMS ......................................................................................................... 922. 5.2. RESPIRATORY QUOTIENT (RQ) .............................................................................. 953. 5.3. CALCULATION OF NE CONTENT OF RUMINANT DIETS .................................. 964. 5.4. FACTORS AFFECTING ENERGY METABOLISM AND ENERGY REQUIREMENTS OF FARM ANIMALS .................................................................................................................... 96

4.1. 5.4.1. Energy metabolism ........................................................................................ 964.2. 5.4.2. Energy requirements ...................................................................................... 97

5. 5.5. COMPARATIVE SLAUGHTER TECHNIQUE .......................................................... 976. Test questions: ...................................................................................................................... 977. Recommended reading ......................................................................................................... 97

7. 6. NUTRIENT REQUIREMENT OF BODY PROCESSES AND PRODUCTIVE FUNCTIONS 981. 6.1. THE NUTRIENT REQUIREMENTS OF MAINTENANCE ...................................... 98

1.1. 6.1.1. Energy requirement of maintenance ............................................................. 981.2. 6.1.2. Protein requirement of maintenance ............................................................. 99

2. 6.2. NUTRIENT REQUIREMENTS OF WEIGHT GAIN ................................................. 992.1. 6.2.1. Energy requirement of weight gain ............................................................... 992.2. 6.2.2. Protein requirement of weight gain ............................................................... 99

3. 6.3. THE NUTRIENT REQUIREMENTS OF MILK PRODUCTION ............................ 1003.1. 6.3.1. The energy requirement of milk production ................................................ 1003.2. 6.3.2. Protein requirement of milk production ...................................................... 100

4. 6.4. NUTRIENT REQUIREMENTS OF WOOL PRODUCTION ................................... 1015. 6.5. THE NUTRIENT REQUIREMENTS OF EGG PRODUCTION .............................. 101

5.1. 6.5.1. The energy requirement of egg production ................................................. 1015.2. 6.5.2. The protein requirements of egg production ............................................... 101

6. Test questions: .................................................................................................................... 1027. Recommended reading ....................................................................................................... 102

8. 7. FEED CONSERVATION ........................................................................................................ 1031. 7.1. FEED CONSERVATION WITH DRYING ................................................................ 103

1.1. 7.1.1. Drying forages ............................................................................................. 1031.2. 7.1.2. Factors affecting the quality of hays ........................................................... 1041.3. 7.1.3. Hay making losses ....................................................................................... 1041.4. 7.1.4. The technology of hay making .................................................................... 1051.5. 7.1.5. Traditional order drying with the help of solar energy ................................ 105


Nutrition

1.6. 7.1.6. Drying with air-flow .................................................................................... 1071.7. 7.1.7. Cereal Grain drying ..................................................................................... 108

2. 7.2. FEED CONSERVATION BY FERMENTATION ...................................................... 1092.1. 7.2.1 Main microbial groups of ensilage ............................................................... 1102.2. 7.2.2. The process of fermentation ........................................................................ 1112.3. 7.2.3. Influential factors of the fermentability of feedstuffs .................................. 1122.4. 7.2.4. Grouping of feeds based on their fermentability ......................................... 1132.5. 7.2.5. Nutritional loss during ensiling ................................................................... 1142.6. 7.2.6. Making haylage ........................................................................................... 1142.7. 7.2.7. Chemical preservation ................................................................................. 1152.8. 7.2.8. Silo types ..................................................................................................... 115


9. 8. FEED PROCESSING .............................................................................................................. 1201. 8.1. TREATMENT OF FORAGES .................................................................................... 121

1.1. 8.1.1. Slicing .......................................................................................................... 1211.2. 8.1.2. Pureeing ....................................................................................................... 1211.3. 8.1.3. Chaffing ....................................................................................................... 1211.4. 8.1.4. Curing .......................................................................................................... 1211.5. 8.1.5. Grinding ....................................................................................................... 1221.6. 8.1.6. Pelletization, granulation ............................................................................. 1221.7. 8.1.7. Briquetting ................................................................................................... 1221.8. 8.1.8. The digestion of straw ................................................................................. 122

2. 8.2. THE TREATMENT OF SEEDS ................................................................................. 1222.1. 8.2.1. Seed treatment methods without using heat ................................................ 1232.2. 8.2.2. Heat treatments ............................................................................................ 124


10. 9. IMPACT OF DIETARY NUTRIENTS ON IMMUNE STATUS OF ANIMALS ................ 1281. 9.1. DEVELOPMENT OF THE NUTRITIONAL IMMUNOLOGY .............................. 1282. 9.2. INFLUENCE OF THE NUTRIENT SUPPLY ON THE IMMUNE FUNCTION 129

2.1. 9.2.1. Protein and amino acid supply .................................................................... 1292.2. 9.2.2. Fat, fatty acids ............................................................................................. 1302.3. 9.2.3. Carbohydrates .............................................................................................. 131


11. 10. EFFECT OF ANIMAL NUTRITION ON PRODUCT QUALITY .................................... 1331. 10.1. TYPES OF MEAT QUALITY .................................................................................. 1332. 10.2. QUALITY, SAFETY AND ACCEPTABILITY OF ANIMAL ORIGIN FOODSTUFFS ................................................................................................................................................. 1333. 10.3. EFFECT OF NUTRIENT INTAKE ON MEAT QUALITY .................................... 1344. Test questions: .................................................................................................................... 1365. Recommended reading ....................................................................................................... 136

12. 11. RELATIONSHIP BETWEEN ANIMAL NUTRITION AND ENVIRONMENTAL POLLUTION .......................................................................................................................................................... 137

1. 11.1. NUTRITION AND ENVIRONMENTAL POLLUTION ......................................... 1372. 11.2. REDUCTION OF NITROGEN EXCRETION ........................................................ 1373. 11.3. REDUCTION OF PHOSPHORUS EXCRETION ................................................... 1384. Test questions: .................................................................................................................... 1395. Recommended reading ....................................................................................................... 139

13. 12. IMPACTS OF CLIMATE CHANGE ON FEED CROP PRODUCTION, ANIMAL PRODUCTION AND QUALITY OF ANIMAL FOOD PRODUCTS ........................................... 140


Nutrition

1. 12.1. THE EFFECT OF CLIMATE CHANGE ON FEED CROP PRODUCTION .......... 1402. 12.2. THE IMPACT OF CLIMATE CHANGE ON THE PERFORMANCE OF FARM ANIMALS AND THE QUALITY OF ANIMAL FOOD PRODUCTS ................................ 141

2.1. 12.2.1. Thermoneutral zone and thermoregulation of farm animals ..................... 1412.2. 12.2.2. The effect of heat stress on the production of pigs and pork quality ........ 143

3. 12.3. FEEDING STRATEGIES IN RESPONSE TO CLIMATE CHANGE ..................... 1463.1. 12.3.1. Feeding strategies during cold stress ......................................................... 1463.2. 12.3.2. Feeding strategies during heat stress ......................................................... 146

4. 12.4. CONCLUSION ......................................................................................................... 1475. Test questions: .................................................................................................................... 1486. Recommended reading ....................................................................................................... 148

14. 13. CONCEPT OF THE TOTAL AND ANIMAL NUTRITION .............................................. 1491. 13.1. PRECISION LIVESTOCK FARMING (PLF) ......................................................... 1492. 13.2. PRECISION ANIMAL NUTRITION ....................................................................... 1493. 13.3. TOTAL ANIMAL NUTRITION ............................................................................... 1504. Test questions: .................................................................................................................... 1525. Recommended reading ....................................................................................................... 152


Az ábrák listája1.1. Figure 1. Relationship among traditional animal nutrition and other related sciences (Babinszky and Halas, 2009) ......................................................................................................................................... 51.2. Table 1. The relationship between daily ileal digestible lysine intake, daily weight gain, daily protein deposition and feed conversion ratio (Halas and Babinszky, 2000) .................................................... 51.3. Figure 2. The modeling process (adapted from Black, 1995) ....................................................... 71.4. Figure 3. „From farm to fork” precision food production and traceability chain under changed climate condition ............................................................................................................................................... 82.1. Figure 4. Components of different fractions in the proximate analysis of feedstuffs (Weende method) ............................................................................................................................................................ 102.2. Figure 5. Grouping of the polysaccharides of feed (Schutte, 1991) ........................................... 112.3. Table 3. NSP content of some feed component and the digestibility of NSP in pigs (Pugh, 1993) 132.4. Picture 1. Near infrared reflectance spectroscopy ...................................................................... 143.1. Figure 6. The polygastric stomach of the ruminants ................................................................... 153.2. Figure 7. Stomach of pig and horse ............................................................................................ 163.3. Table 4. The relative capacity of the different parts of digestive apparatus at different animals 164.1. Table 6. Classification of amino acids (Boisen, 1997) ............................................................... 254.2. Table 7. Biological value (BV) of selected feeds for growing pigs (Armstrong and Mitchell, 1955) ............................................................................................................................................................ 264.3. Table 8. Net protein utilization (NPU) of selected plant and animal protein sources (After Miller and Bander, 1955; Johson and Coon (1979 .............................................................................................. 274.4. Figure 8. The shape of the linoleic acid ...................................................................................... 314.5. Figure 9. Changing the lipid quality during storaging (Schmidt, 1996 ...................................... 334.6. Figure 10. The different spacing forms of the glucose ............................................................... 344.7. Figure 11. Amylose “spring” ...................................................................................................... 364.8. Figure 12. The shape of the amylopectin .................................................................................... 364.9. Figure 13. Different plants, different starch shapes (upper left- potato, lower right- wheat, the other two peas) ............................................................................................................................................ 364.10. Picture 2. The structure of the cellulose .................................................................................... 394.11. Figure 14. Lignin molecule in the cellulose .............................................................................. 404.12. Table 13. Vitamins playing a significant role in animal nutrition ............................................. 454.13. Table 14. Designation of ‘obsolete vitamins’ according to their alphabetical terminology and trivial (generic) names .................................................................................................................................. 464.14. Table 15. Recommended dosages of L-carnitine in animal nutrition* ..................................... 614.15. Table 16. Essential fatty acid requirements for various animals a,b ......................................... 634.16. Table 18. Groups of trace and ultra-trace elements for animal and man .................................. 674.17. Figure 15. The chelate part of the haemoglobin ....................................................................... 705.1. Figure 16. Origin of amino acid losses at the terminal ileum ..................................................... 745.2. Figure 17. Expression of apparent, standardises and true ileal amino acid digestibilities as a function of amino acid intake ........................................................................................................................... 755.3. Figure 18. Stages in the surgical procedures used to establish an ileo-rectal anastomosis in pig 765.4. Figure 19. Simple T-cannulation technique in pig ...................................................................... 765.5. Figure 20. Re-entrant cannulation technique in pig .................................................................... 775.6. Figure 21. PVTC (post valve T-cannula) technique in pig ......................................................... 785.7. Table 19. Digestibility of crude protein and amino acid content of full fat soya in growing pigs 785.8. Table 20. Effect of toasting on the faecal and ileal digestibility of crude protein, lysine, methionine and cystine in soybean meal (%) (van Weerden, 1985) ..................................................................... 795.9. Table 21. Essential amino acid profile in ideal protein (lysine: 100 %) based on the total and ileal digestible amino acid content (Wang and Fuller, 1989) .................................................................... 805.10. Table 24 The ideal pattern of amino acids during pregnancy and lactation (Close, 1995) ....... 81


Nutrition

5.11. Table 25. Correlation between the ileal and faecal digestibility of dietary crude protein and the weight gain and FCR of growing - finishing pigs (Dierick et al., 1987) ........................................... 815.12. Figure 22. Dropping digestibility (intact bird) .......................................................................... 835.13. Figure 23. Dropping digestibility (caecectomized bird) ........................................................... 835.14. Figure 24. Faecal digestibility (cannulated/colosomized/bird) ................................................. 845.15. Figure 25. Ileal digestibility (cannulated bird) ......................................................................... 855.16. Table 26. True digestibility of amino acids in sorghum based on the collection of faeces and excreta (Bragg et al., 1969) ............................................................................................................................ 855.17. Table 27. Ileal and dropping digestibility of selected amino acids of soybean meal (Bielori and Iosif, 1987) .................................................................................................................................................. 855.18. Table 28. Total and ileal digestible amino acid content (g/kg) of selected feed ingredients (CVB, 1997) .................................................................................................................................................. 855.19. Table 29. Total and apparent digestible amino acid content of grower diet for broilers* (Tossenberger and Babinszky, 1998) ......................................................................................................................... 865.20. Table 30. Recommended ideal protein composition for broilers by age group* ...................... 875.21. Table 31. Nutrient content of the diets (%) (Rostagno et al., 1995) ......................................... 875.22. Table 32. Summary of results of the broiler growing trial (Rostagno et al., 1995) .................. 885.23. Figure 26. In vitro digestibility of crude protein ...................................................................... 896.1. Figure 27. Flow diagram of energy terms ................................................................................... 926.2. Table 33. Respiratory quotient of selected nutrients ................................................................... 958.1. Figure 28. Fix chamber baler .................................................................................................... 1068.2. Figure 29. Variable chamber baler ............................................................................................ 1068.3. Picture 3. Finnish broaches ....................................................................................................... 1068.4. Picture 4. Swedish rack ............................................................................................................ 1078.5. Picture 5. Hay dryer pyramid ................................................................................................... 1078.6. Figure 30. Special rack for air-flow drying .............................................................................. 1088.7. Figure 31. The ways of the air in a tower dryer ........................................................................ 1088.8. Picture 6. Stack silo .................................................................................................................. 1168.9. Picture 7. Production process of a plastic tunnel silo ............................................................... 1168.10. Picture 8. Bale silo .................................................................................................................. 1168.11. Figure 32. Different bunker silos ............................................................................................ 1178.12. Figure 33. The operation of silage block cutter ...................................................................... 1178.13. Figure 34. Tower silo .............................................................................................................. 1189.1. Table 35. The effect of the grinding for the digestibility of nutrients of barley in pigs ........... 1239.2. Figure 35. The operation of roller pounder (1. spout, 2. valve, 3. rollers, 4. gap controller, 5. electro-motor) .............................................................................................................................................. 1239.3. Figure 36. The operation of the hammer grinder (1. motor, 2. coupling, 3. rotating part, 4. hammer, 5. air inlet, 6. suction fan, 7. ventilator, 8. grind surface, 9. basement, 10. control plate, 11. hindering plate against snapping back, 12. spout, 13. screen) .................................................................................. 1249.4. Figure 37. The process of flaking (1. spout, 2. rollers, 3. wetting auger, 4. steamer, 5. jig, 6. flaker, 7. dryer-cooler, 8. ventilator) ............................................................................................................... 1259.5. Figure 38. The process of the extruding (1. spout, 2. grinder, 3. extruder, 4. dryer-cooler, 6. grinder) .......................................................................................................................................................... 1269.6. Figure 39. The granulation (1. ring jig, 2. deflectors, 3. roller cross, 4. rollers, 5. knife, 6. pellet) 12610.1. Table 36. Effect of dietary threonine on serum IgG and bovine serum antibody production in pigs (Defa et al., 1999) ............................................................................................................................ 13011.1. Figure 40. Relationship among food safety, quality and acceptability (Mossel and van Logtestijn, 1989) ................................................................................................................................................ 13311.2. Figure 41. Linear-plateau and curvilinear relationship between protein intake and protein deposition in case of two different energy intakes (Bikker, 1994) .................................................................... 13511.3. Figure 42. The effect of altering the ratio of lysine/digestible energy on the fat content of growing pigs (LW: 20-45 kg) (Batterham et. al., 1990) ................................................................................. 13511.4. Figure 43. Lysine and digestible energy requirements for improved pigs (Varley, 2001) ...... 13612.1. Table 37. Reducing the protein content of diets and impact of amino acid supplementation on the


Nutrition

nitrogen excretion of fattening pigs (Flachowsky, 1995) ................................................................ 13712.2. Table 38. Phosphorus retention in growing pigs by several author ........................................ 13812.3. Table 39. Effect of different phytase doses on phosphorus balance in growing pigs (25-60 kg LW)1 (Tossenberger et al., 1994) ............................................................................................................... 13913.1. Figure 44. Relationship between ambient temperature and heat production of farm animals 14213.2. Table 40. Lower and upper critical temperature of farm animals at different age or body weight (FASS, 2010) ................................................................................................................................... 14213.3. Table 41. Effect of ambient temperature on performance of multiparous lactating sows (Quiniou and Noblet, 1999) ................................................................................................................................... 14413.4. Table 42. Effect of dietary energy source on the energy balance of lactating sows >and on the energetic efficiency of milk production (Babinszky, 1998) ............................................................ 14414.1. Figure 45. The concept of total nutrition (Adams, 2001) ....................................................... 151


A táblázatok listája1.1. Table 2. Three categories of pigs have been identified depending upon their rate and composition of body gain (Close, 1994) ....................................................................................................................... 63.1. Table 5. Chemical composition of the different faeces of rabbit ................................................ 194.1. Table 9. The saponification numbers of different kind of fats (Church and Pond, 1988) .......... 294.2. Table 10. The iodine numbers of different kind of fats (Church and Pond, 1988) ..................... 304.3. Table 11. Crude fibre need of different kind of animals ............................................................. 424.4. Table 12. The reduction of digestibility by 1% increase of the crude fibre content ................... 434.5. Table 17. We can see the quantity of different kinds of mineral elements in the animal organisms ............................................................................................................................................................ 675.1. Table 22. Essential amino acid profile in ideal protein (lysine: 100 %) for maintenance and weight gain (Henry, 1993) ............................................................................................................................. 805.2. Table 23. Percentage of essential amino acids in ideal protein (lysine: 100 %) for pigs in the growing and fattening stages (Baker and Chung, 1992) .................................................................................. 808.1. Table 3. The connection between dry matter content and the pH level .................................... 111


Tárgymutató


1. fejezet -PREFACE

Feeding and suitable nutrient supply of farm animals in the 21st century is of even greater importance than it was earlier. Importance of this science is supported by several facts.

Some 70% of the total cost of the animal production is given by costs related to feeding. That means that just a few percent improvement in the feeding efficiency can markedly decrease specific cost of the product, thus it has a large contribution to improvement of the production economy.

It is quite clear too, that quality of the food products of animal origin can be substantially influenced by means of feeding. However it has to be noted that feeding may not only improve but to deteriorate quality of the food product of animal origin as well. Thus responsibility of the feeding experts is extremely high as far as quality and safety of food products of animal origin are considered.

Nowadays the up-to-date feeding utilizes the latest knowledge of not just the classic (traditional) feeding science, but that of the associated sciences (physiology, molecular biology, molecular genetics, immunology, microbiology, information technology, some areas of the technical sciences) as well, for the production of a safe, good quality food product of animal origin more appropriate for the human nutritional demand.

In the state-of-art feeding the systematic thinking, systematic integration of the professional and scientific knowledge to answer a specific question is of vital importance. It is helped by concept of the so-called precision feeding, where information technology and its knowledge is also an important precondition for the economic production of food commodity of animal origin.

Objective of the present university lecture notes is – together with curriculum of the feeding lectures and that of the practices – to help learning most important elements of the up-to-date feeding and to help acquire the way of thinking which is so important to solve the tasks of the modern animal feeding and nutrition.

We hope we shall be able to realize the above objectives during the feeding courses and by acquiring knowledge from the present lecture notes.

Debrecen, April, 2013

Prof. Dr. László Babinszky

Head of Department

Department of Feed and Food Biotechnology

Dr. Péter Bársony

Assistant professor

Department of Animal Breeding

INTRODUCTION

1. 1. The role and importance of animal nutritionNutrition of animals is almost coeval with animal farming. In the beginning hardly any consciousness could be found in this activity. But thanks to experiences gained during the centuries, and later to the explosive development in natural science and other sciences, nutrition has taken up most important part in the animal production.

It is not a purpose of this sect1 to review the history of the nutrition, a lot of outstanding authors have already done it in different textbooks and review articles.

We’d like to call your attention here to the fact that nutrition/feeding doesn’t mean that just nutrient and energy


requirements of the farm animals are tried to be met as correctly as it is possible, but it means that this science has a key role in manufacturing good quality and safe food products of animal origin, and also in profitable production of the animal agriculture as well.

Animals that do not receive the proper nutrition are more likely to develop health and reproductive problems, and to be less productive and marketable.

It should be stressed as well, that in the last 15 years perception of animal nutrition has changed immensely. The importance of animal nutrition in animal health, animal welfare and quality of animal products has come into the limelight when nutritional value for humans is considered.

Thus the up-to-date nutrition/feeding is a science involving different sciences and different concepts. Main objective of this science is the production of high quality, safe and traceable products of animal origin with the lowest possible load on the environment.

In order to reach these objectives the up-to-date nutrition science applies concepts like ileal amino acid digestibility, ideal protein, or that of the so called total nutrition and precision feeding. In order to reach the same goals results of some other scientific fields that were mentioned in the Preface are also applied.

The safe, traceable, transparent and profitable animal source food production can only be imagined via practical realization of a precision food chain from the arable land to the table, thus in case of thinking in a complex system. Feeding/nutrition plays a key role in this food chain as well.

Situation of the feeding is aggravated by the need to realize the precision food chain under changing climatic conditions. Thus – according to philosophy of the product chain - the nutritional experts have not only to cooperate with nutritional biologists, molecular geneticists, molecular biologists, immunologists, human physicians, technical experts, information technology specialists, but with plant breeders and climatologists as well. The one who is unable to participate in this diversified and sophisticated cooperation built on a uniform philosophy won’t be able to answer nutritional challenges of the 21st century.

Test questions:

1. What is the task of the up-to-date nutrition?

2. Experts of which scientific fields have to cooperate in the precision food chain program?

3. What concepts are applied in the up-to-date nutrition/feeding?

2. Challenges in the 21st century animal nutritionAnimal nutrition in the 21st century aims to provide safe and good quality foodstuffs of animal origin besides a high efficiency of production and a low level of environmental pollution. These criteria, however, contribute to the complexity and rapid expansion of nutrition science. The demand of the human population is increasing, which needs to be supplied from a diminishing agricultural area, maintaining at the same time sustainability of production.

According to the global trends, the challenges facing animal nutrition in the 21st century can be summarized as follows: more awareness and activity of participation is needed in animal production to supply quality and safe food in sufficient quantities, in accordance with the requirements of the society. Considering the limited nature of available agricultural area, the efficiency of animal production needs to be improved. This can be achieved by increasing

1. biological efficiency,

2. technological efficiency and

3. economic efficiency.

The science of animal nutrition deals with the first two factors by using advanced knowledge. One of the practical solutions for saving grains for human consumption is to increase the amount of feedstuffs available for animal nutrition by using by-products. This concept is also in agreement with the principles of sustainability.


The effect of climatic change on crop production and animal nutrition should be studied in the near future, together with the investigation and evaluation of different climate scenarios. Another aspect of sustainable production is the relationship between animal production and environmental protection. Animal nutrition has a great impact on reducing environmental N, P, CH4 and microelements pollution caused by animal farming.

Innovation in animal nutrition aims at high quality of production besides a low level of environmental pollution. Due to limited space the challenges of 21st century in animal nutrition will be presented via examples from swine nutrition.

2.1. 2.1. The application of the latest scientific findings in pig nutrition and in innovationIn the interest of enhancing the efficiency of pork production, the implementation of the latest scientific results in practical production is of key importance. The question, however, is whether the challenges of the 21st century can be faced using the knowledge of traditional animal nutrition science. Given that this is not very likely, it is necessary to include the new areas of animal nutrition in the innovation activity. This is not a new process, since nutrition physiology, or nutrition immunology has already become a highly important part of today’s modern animal nutrition. Figure 1 shows those areas of natural sciences and/or technical sciences that should be integrated into the traditional animal nutrition science in order to come up with an adequate answer to the challenges of today. Such relatively novel fields are for instance molecular nutrition or the mathematical modeling of growth. Precision nutrition, which is an innovative area of animal nutrition, is a unique combination of traditional animal nutrition science, new animal nutrition knowledge incorporating natural science areas and informatics.

2.2. 2.2. Main research areas foreseen in animal nutritionBased on a review of the relevant literature the following main research areas of pig nutrition can be envisaged for the near future:

1. Studies pertaining to the properties of animal feeds (e.g. new energy and protein feeds, interactions between the various nutrients, alternatives to growth promoting antibiotics, mycotoxin contamination and the means to reduce it, issues of genetically modified organism (GMO) feeds, study of the relationship between climatic change, feed crop production and animal nutrition, etc.), (see Chapter 12).

2. Research related to molecular nutrition.

3. Nutritional immunology studies (effect of nutrients on the cellular and humoral immune status of the animals; see Chapter 9).

4. Research in nutritional microbiology (e.g. microbiological processes in the intestinal tract and their impact on animal production).

5. Study of the nutrient requirements of high genetic potential animals (the relationship between genetics and nutrition; see this chapter sect1 2.2.2. and Chapter 10).

6. Modeling of animal production (predicting animal production with mathematical models).

7. Develop new in vitro techniques (develop novel, rapid, high-precision in vitro techniques for determining the digestibility of proteins, carbohydrates and other nutrients; see Chapter 4).

8. Develop environmentally friendly feeding technologies (primarily the development of feeding technologies aimed at reducing N and P excretion; see Chapter 11).

9. Work out integrated research and innovation programs for the “from farm to fork” food chain in the interest of producing safe and traceable food products of animal origin.

10. Apply precision nutrition in the production of animal products; see Chapter 13).

This chapter focuses on and discusses in detail only some of the aforementioned research areas due to their extensive volume.


1.1. ábra - Figure 1. Relationship among traditional animal nutrition and other related sciences (Babinszky and Halas, 2009)

2.2.1. 2.2.1. Molecular nutrition research

Molecular nutrition is a new area of animal and human nutrition, developed on the basis of genomics, ulinking them to nutrition science. In the past 20 years, the introduction of powerful new molecular techniques has made it possible to advance knowledge in animal and human biology. In most disciplines a reductionist approach is used, but in nutrition an integrationist approach is needed to deal with the complexity of the subject.

Molecular nutrition investigates the roles of nutrients at the molecular level, such as signal transduction, gene expression and covalent modifications of proteins.

The micronutrients at the cellular level modulate the milieu in which biochemical and genetic metabolisms operate, and thus they can influence gene expression. Nutrient transport mechanisms and intracellular trafficking, apoptosis, intracellular signaling mechanisms and the role of nutrients, nutrient interactions with gene expression, and epigenetic regulation of gene expression by nutrient dependent reactions are all included in molecular nutrition.

2.2.2. 2.2.2. Relationship between genetics and nutrition

The growth performance and the chemical composition of the carcass (the meat quality) are affected by many factors. One of the most important factors is the amino acid / energy ratio of the diet.

It is well known, that for pigs the primary limiting amino acid is usually lysine. Table 1 illustrates the strong correlation between ileal digestible lysine intake and average daily weight gain, and also between the daily protein deposition and the feed conversion rate (Halas and Babinszky, 2000).

In consequence, it is indispensable that we aim for creating the best possible lysine / energy (DE) ratio during diet formulation, in order to enhance protein deposition (Babinszky, 2006).

The trial results show, that in the case of growing pigs (between 25 and 60 kg of live weight) the lowest fat deposition level can be expected with an 0.63 g ileal digestible lysine / MJ DE ratio. The data from these studies suggest, that any deviation from this lysine / energy ratio will lead to a higher fat content of the carcass and consequently to the deterioration of the meat quality.

1.2. ábra - Table 1. The relationship between daily ileal digestible lysine intake, daily weight gain, daily protein deposition and feed conversion ratio (Halas and Babinszky, 2000)


The results of the relevant studies also show, that the ratio determined for 25 - 60 kg live weight will decrease to 0.50 g ileal digestible lysine / MJ DE during the second phase of fattening (between 60 and 105 kg of live weight) (Batterham et.al., 1990).

It should be noted however, that the foregoing lysine / energy ratios pertain to hybrids with a so-called average genetic potential (normal pig).

Three categories were set up for hybrids in the literature (Close, 1994):

1. Superior, genetically improved pigs;

2. Normal pigs;

3. Traditional, unimproved pigs.

The average daily weight gains and protein content of the empty body, characteristic of each category, are shown in Table 2.

1.1. táblázat - Table 2. Three categories of pigs have been identified depending upon their rate and composition of body gain (Close, 1994)

Categories Growth rate (kg/d) Protein content of empty body (g/kg)

Superior, genetically improved pigs up to 1.2 180

Normal pig up to 1.0 170

Traditional, unimproved pigs up to 0.8 160

Note: the assumption is, that maximum growth rate is achieved at a body weight of 60 kg an is then maintained at a constant level up to 100 kg body weight, that is in a linear-plateau fashion.

Results of the studies conducted so far show, that when the lysine / energy ratio in the diet of hybrids belonging to the first category (improved pigs) is the same as in the feed of normal pigs, these will deposit access fat by the end of the fattening period, i.e. the quality of the meat will deteriorate substantially. For this reason Varley (2001) suggests to feed these pigs with a diet containing 0.7 g ileal digestible lysine per MJ DE during the first phase of fattening (between 20 and 55 kg of live weight), and 0.6 g during the second phase (between 55 and 100 kg live weight).

These data stress the importance of knowing the genetic potential of our growing / finishing herd, because this knowledge is indispensable during diet formulation for establishing a proper lysine / energy ratio, so that the quality of meat can satisfy the criteria of human nutrition even in the case of the improved, high-producing pigs,


(see more details in Chapter 10).

2.2.3. 2.2.3. Modeling (prediction) of animal production

Nutritional simulation models transform the knowledge and concepts of growth process or (milk) production into mathematical equations by developing algorithms. Integrating these equations, the model predicts the production from the nutrient intake. Unlike empirical ones, the mechanistic model’s equations are based on the knowledge of biological, biochemical, physiological and environmental response. Thus, with animal level models the effects of desirable and undesirable changes can be simulated (Halas et al., 2004a,b).

Nutritional models, therefore, are an effective tool for optimizing production and carcass quality and thus by integrating them into farm management programs they can improve the profitability. The main purposes of using models in practice are the following: define the number of diets fed (phases used) in the whole feeding period; decision making in the use of alternative feed components (such as sugar beet pulp, soya hulls, various by-products, etc.); define the optimal slaughter weight for a certain livestock and in case of a certain feed; help to formulate diets that reduce environmental pollution (N and P excretion) without impairing the quality of production. Mechanistic growth models can be integrated into the feed evaluation systems as well. By its nature - being developed on the basis of biological, physiological or biochemical principles - a mechanistic model can be used in education and research. The consecutive equations help to understand easily the mechanism underlying the growth process, but a model also highlights areas in which knowledge is inadequate and thus helps to formulate new scientific questions.

The major steps in a modeling process can be seen in Figure 2. The animal is a physiological system with measurable features (physiological data) and biological processes (physiological pathways). The first step in the modeling process is to carry out an investigation to collect basic data, such as weekly body weight readings, daily protein and fat deposition or daily feed intake, etc. The physiological process and the control of the system are then developed from this information. Traditionally in science, these two steps are repeated many times until the system can be described at some uniform level of detail (Black, 1995). The concepts and data are transformed into mathematical equations by algorithms that can be solved rapidly by computer to provide a quantitative and dynamic approach of the system.

1.3. ábra - Figure 2. The modeling process (adapted from Black, 1995)

The next step is to check the validity of the model with regard to pathways and data, by comparing predictions with the trial results. Whenever there is a considerable difference between the model predictions and experimental observations, new approaches of pathway and equation parameters can be devised and tested within the model. The modeling process begins again in that case. When model outcome and the experiences agree over a wide range of different circumstances, some confidence in the understanding of the system is obtained (Black, 1995), that this could be the final model.

The model presented herein predicts the growth of growing and finishing pigs. The relevant data of literature suggest, however, that in addition to the growth model the development of new models can also be expected in the near future, which will be suitable to predict the quality of animal products (e.g. meat) as well, improving thereby the economics of production.

2.2.4. 2.2.4. “From farm to fork chain” integrated research and innovation


programs

In the interest of producing high quality and safe animal food products (e.g. meat), it is necessary to examine the entire chain both in research and in the production of animal products. Therefore, the production of high quality and safe animal food products demands that already at the first ulink of the animal product production chain, i.e. at field crop production high quality and safe production practices be in place. Accurate information are required about soil management, plant protection, and as to whether GMO grain is produced on the farm in question. The next ulink in the production chain is the animal feed industry. At this step in addition to the feed ingredients of plant origin also the industrially manufactured feed ingredients and feed supplements need to be controlled. Furthermore, each step of the compound feed manufacturing process and eventual manipulations in the feed mill (such as hydrothermic treatment, extruding, expanding, micronizing or other) should be controlled. The resulting compound feed is transferred to the pig operation, where all important data of each phase in the feeding and fattening process must be recorded together with the herd data. Having reached the slaughter weight the herd is transported to the slaughterhouse or the processing plant. Here again each processing stage is controlled and the data are entered in the central terminal (data file) of the product chain, where upon the evaluation of the data it can be discovered immediately if the activities at a certain point of the production chain deviate from the regulations, or if the data measured do not meet the regulations and the quality criteria. At the end of the product chain the output is a "food product of planned quality and safety derived from a planned feed" controlled at every stage of production, which when delivered to the supermarket shelves and cold counters can also be verified by the consumers themselves with the help of a bar-code. Figure 3 presents the entire food production chain outlined in the above under the title "from farm to fork". The purpose of this research and development and innovation (R+DI) project is to supply to the consumers animal products of the highest possible quality and safety. To this end however, crop production, feed industry, livestock production and the food processing industry and trade need to work in very close cooperation. Above all this it is also necessary that the researchers involved in the fields of animal nutrition, human nutrition, nutrition biology, nutritional immunology, molecular nutrition and also the information technology specialists work together.

1.4. ábra - Figure 3. „From farm to fork” precision food production and traceability chain under changed climate condition

It is natural, that such a highly qualified research team committed by the foregoing philosophy will only be able to perform any high standard work in case it possesses a high standard research basis. This means that laboratories and a sufficiently comprehensive and accurate technical data base, quality criteria pertaining to each member of the production chain, and a high standard informatics background (software, hardware) are required. This type of high-level cooperation enables the controlling of every single point of the product chain in the interest of producing safe animal products.


In recent years the number of programs called "from farm to fork chain", "from field to consumer chain" or "from feed to food chain" is continuously increasing in the EU, the US and Canada, equally. It is a task of the near future that Central Europe should participate in these and similar research programs more intensively.

3. Test questions:1. What are the most important challenges in the 21st century animal nutrition?

2. List the most important research areas in the 21st century animal nutrition.

3. Give the main purposes of using mathematical models in animal nutrition.

4. Which are the most important elements of the precision food production chain?

4. Recommended readingBabinszky, L. 1996. The feed – to food- to environment chain possibilities in nutrition to improve meat quality and to reduce nitrogen and phosphorus excretion in pigs. Proc. of 4th International Symposium „Animal Science Days 8-10 September 1996. Faculty of Animal Science, Kaposvár. 7-23.

Babinszky, L., Dunkel, Z., Tóthi, R., Kazinczi, G., Nagy, J. 2011. The impacts of climate change on agricultural production, Hungarian. Agricultural. Research, 2:14-20.

Babinszky, L., Halas V. 2009. Innovative swine nutrition: some present and potential applications of latest scientific findings for safe pork production. Italian Journal of Animal Science. 8. (Suppl. 3): 7-20.

Moughan, P.J., Verstegen, M.W.A., Visser-Reyneveld, M.I. (Eds). 1995. Modeling growth in the pig. Wageningen Pers, Wageningen, NL

Moughan, P.J., Verstegen, M.W.A., Visser-Reyneveld, M.I. (Eds). 2000. Feed evaluation principles and practice. Wageningen Pers. Wageningen. NL.


2. fejezet - 1. CHEMICAL COMPOSITION OF FEEDSTUFFS1. 1.1. COMPONENTS OF DIFFERENT FRACTIONS IN THE PROXIMATE ANALYSIS OF FEEDSTUFFS (WEENDE METHOD)The feed of livestock consists mainly of plants and plant products. Solar energy enables plants to synthesize their components (proteins, fats, and carbohydrates) from simple substances such as carbone dioxide from the air, and water and inorganic substances from the soil. Large amounts of energy originating from solar radiation are stored as chemical energy within the plant components.

When animals ingest feed of plant origin the energy content of the feed is used by animals for maintaining body functions such as respiration, blood flow and nervous system, for tissues gain and for formation of animal products, like milk, meat, eggs wool, etc.

In order to produce high quality animal products, one of key issue is the chemical composition of the diet. Much of the existing information we have about the composition of feeds and foods, and parts of animals has been obtained by a scheme of proximate analysis know as the Weende method, named after the experimental station in Germany where it was developed more than 120 years ago. According to this method, a feed sample is divided into six fractions, namely water, ether extract (crude fat), crude fiber, nitrogen-free extract, crude protein and ash (Figure 4). Five of these fractions are determined by chemical analyses, while the sixth (nitrogen-free extract) is determined by calculation (see below in this sect1).

2.1. ábra - Figure 4. Components of different fractions in the proximate analysis of feedstuffs (Weende method)

The Weende method (proximate analysis) has the advantage of being simple, relatively quick, inexpensive, and highly reproducible. This method is still used with minor modifications. After analysis, nutrient composition can be expressed on a dry basis.

Dry matter: the simplest means of determining dry matter is to place the feed sample in an oven at 105 0C and dry it until all the free water has evaporated.

Water content: water content is measured by the difference in weight of a sample before and after drying.

Crude protein (N) content: the crude protein fraction is calculated from the nitrogen content of the sample determined by the Kjeldahl procedure. The feed sample is digested in hot, concentrated sulfuric acid, which converts all the carbon-containing compounds to carbon dioxide, and nitrogen is trapped and subsequently measured and expressed as percentage. The rationale behind this procedure is that all proteins contain nitrogen.


1. CHEMICAL COMPOSITION OF FEEDSTUFFS

However, it should be noted that not all nitrogen-containing compounds are proteins. Therefore, the protein determined by this procedure called “crude protein”. Since proteins contain an average of 16% nitrogen, the crude protein content is derived by multiplying the N figure by 6.25 (100/16 = 6.25). It should be stress out that the Kjeldahl procedure provides only an estimate of the quantity of nitrogen present and does not provide any indication of quality.

Crude fat (ether extract): the crude fat content is determined by extracting the sample with ethyl ether or a similar organic solvent or combination of solvents, such as chloroform and ethyl alcohol. This procedure requires that a small sample of feed be placed in a specially designed container. The solvent is dripped though the sample, a process that removes the fats and other soluble substances. The ether extract fraction can contain many other substances other than true fats. The residue obtained after evaporation of the solvent is the ether extract, also called „crude fat” (Soxhlet method). The Soxhlet method provides no information relating to the fatty acid composition.

Crude fiber: the analysis for crude fiber was developed many years ago. It involves boiling (refluxing) a known amount of ground feed sample (usually, the fat has been extracted from the sample) in a weak acid solution, filtrating and boiling in a weak solution of alkali, and filtering and drying. The residue remaining is the crude fiber. This procedure has a number of disadvantages. It is slow, tedious, and not very repeatable, and the information is less applicable to some feeds than to others.

Ash content: the ash content is determined by ignition of a sample at 500 0C. Organic compounds are removed at this temperature. The residue represents the inorganic constituents of the sample.

Nitrogen-free extract (NFE): is calculated and not actually determined using a laboratory procedure. The NFE is an estimate of the readily available carbohydrates (sugars, dextrins, starches). The following formula is used to calculate the NFE content of a feed sample:

NFE = 100 – (crude protein + crude fat + crude fiber + ash)

Gross energy (GE): the energy content of a feed is obtained by using an instrument called an oxygen bomb calorimeter. A small sample of known weight (1-2 g) is placed in the oxygen bomb calorimeter and filled with oxygen under pressure. The bomb is then placed in a container of water of known volume, the sample is ignited, and the change in water temperature is monitored. So, the energy value of a given sample actually is determined by burning it and measuring the heat produced. However, it should be noted that not all the gross energy value of a feed sample is available to animals because of the losses of energy that occur during digestion and metabolism.

2. 1.2. DETERMINATION OF NEUTRAL-DETERGENT FIBER (NDF) AND ACID-DETERGENT FIBER (ADF) (VAN SOEST-METHOD)The neutral-detergent fiber (NDF) and acid-detergent fiber (ADF) methods are becoming more common and are replacing the crude fiber procedure because they more accurately define the carbohydrate components associated with plant materials. Carbohydrates are feed components of diverse composition, and their accurate determination has become possible only with the advent of modern analytical methods utilizing large instruments. Weende analysis enabled only the identification of groups having different properties. The grouping of carbohydrates is presented in Figure 5.

The widely used proximate analysis of feed could distinguish between two large groups of carbohydrates: the crude fiber and the so-called nitrogen-free extract (N-free extract), which is the difference of nutrient content determined by various chemical methods on dry matter basis.

The N-free extract includes starch, sugars, oligosaccharides, β-glucans, pectin, a substantial fraction of hemicellulose and a small amount of cellulose, which are eluted from the sample after acid and then alkaline hydrolysis during crudefiber determination (see above in this sect1).

2.2. ábra - Figure 5. Grouping of the polysaccharides of feed (Schutte, 1991)



Crude fiber is the aggregate of carbohydrates of different type and physicochemical properties, and the shortcoming of its use is that it does not contain some of the plant cell wall constituents. During cooking, 90–100% of the hemicellulose and nearly 40% of the cellulose are dissolved, and thus crude fiber has limited value in evaluating the fiber content of feeds. The fiber fraction determination according to van Soest had been developed in order to overcome this problem (van Soest et al., 1991). Initially this method facilitated the evaluation of ruminant feeds, but today it already provides useful information on pig feeds as well, as it enables not only the quantitative but also the qualitative differentiation of plant cell wall constituents. The fiber fraction determination consists of three main steps: (1) dissolution in a neutral detergent solution, (2) dissolution in an acid detergent solution, and (3) dissolution in 72% sulfuric acid. During boiling in a neutral detergent solution the soluble cell content is extracted from the sample, and the remaining fraction is called neutral-detergent fiber (NDF), which contains hemicellulose, cellulose, lignin, cutin, suberin and also silicic acid. It should be noted, that lignin is polyphenol ether and not carbohydrate. However, the literature discusses the lignin in the group of carbohydrates. During boiling in an acid detergent solution buffered to acidic pH, the hemicellulose is dissolved and the remaining fraction is the acid-detergent fiber (ADF). The third step, i.e. boiling in 72% sulfuric acid, removes the cellulose, and thus only the incrustating substances (lignin, cutin, suberin, silicic acid) are left (acid-detergent lignin: ADL); however, these latter are chemically not polysaccharides. A limitation of the determination of fiber fractions is that the amount of nitrogen bound by the NDF fraction interferes with the accuracy of measurement, and also that NDF may contain starch and residual pectin as well. Because of the above-listed shortcomings, the van Soest method is more and more often criticized. The Total Dietary Fiber (TDF; including Soluble Dietary Fiber, SDF and Insoluble Dietary Fiber, IDF) analysis used in human nutrition gives a more reliable method to determine the (nutritive) value of fiber in monogastric animals, as TDF takes into account also those components (pectins, β-glucans and other soluble sugars) which are washed out from the NDF fraction during analysis (Asp, 1996; Bach-Knudsen, 1997).

Numerous methods have been elaborated for the determination of TDF as well as soluble and insoluble dietary fiber. These methods are based on two different types of measurement procedures: enzymatic-gravimetric and enzymatic-chemical procedures (colorimetric or gas-fluid and high-performance liquid chromatographic determination; AOAC, 1995). IDF and SDF collectively account for the quantity of non-starch polysaccharides (NSP), while the total dietary fiber (TDF) is the sum of IDF, SDF and lignin (AOAC, 1995). The division of carbohydrates into starch and non-starch polysaccharides may seem rather arbitrary in view of the fact that the latter is extremely inaccurate from the chemical point of view. Despite this fact, the two large groups defined in this manner make it easier to estimate the nutritive value of carbohydrates in the practice, primarily because there is a substantial difference between the two types of carbohydrates in terms of digestibility.

3. 1.3. NON-STARCH POLYSACCHARIDES (NSPS)Non-starch polysaccharides represent a group of heterogeneous compounds differing considerably in chemical composition and physical properties both within and between plant sources (Figure 5). The NSP content of selected feed components and the digestibility of NSP in pigs be seen in Table 3.



2.3. ábra - Table 3. NSP content of some feed component and the digestibility of NSP in pigs (Pugh, 1993)

As indicated in Table 3 both the content and digestibility of NSPs vary considerably between feedstuffs. The digestibilities of NSPs are lower than those of starch and sugars. This can be explained by the fact, that NSPs unlike starch and sucrose cannot be hydrolyzed by enzymes produced by mammals or birds themselves.

Furthermore, the efficiency of utilization of energy derived from digested NSP is about 30% lower than of starch and sugars. This has direct implications for the supply of effective energy to the animals. In various studies, the negative effects of increased dietary NSP levels on the digestibility and rate of absorption of nutrients from starch, protein and fats have been demonstrated (de Lange, 2000).

The negative effects of NSPs can be eliminated by adding enzyme (e.g. xylanase, glucanase, etc.) to the diets, (Halas and Babinszky, 2013).

NSP-degrading enzymes are used also in broiler nutrition, as a supplement to concentrates containing high levels of wheat or barley. As has already been mentioned, NSP-degrading enzymes exert their favorable effect by decreasing the viscosity of digesta, which is expected to result in improved nutrient digestibility.

Some research results indicate that, in addition to improving the digestibility of nutrients, the NSP-degrading enzymes also change the microbiological composition of the digestive tract (Bedford, 1996). The change of the microbe population may influence the animals’ general health status as well. The improved digestibility of nutrients and the more favorable health status may collectively improve the performance of animals, too.

Summarizing the research results obtained on enzyme feeding, it can be stated that the nutritive value of feeds can be increased by enzyme supplementation; however, the efficiency of the latter depends on the species and age of the animal and the feed components used. Before using enzyme products, it is expedient to determine the NSP content of feed components, and the actual activity of the enzyme product to be used should also be known. The relevant experimental data indicate that the enzyme supplementation of pig and poultry diets containing high levels of cereals reduces the viscosity of digesta and prevents the antinutritive effect of the NSP fractions. As a result, the digestibility of nutrients and the efficiency of animal production will improve.

4. 1.4. NEAR INFRARED REFLECTANCE SPECTROSCOPY (NIRS) FOR THE ANALYSIS OF FEEDNowadays the feed industry needs an accurate, rapid, and relatively inexpensive means for predicting the total and available nutrient and energy contents of feed ingredients and feeds for use in diet formulation and quality control programme.

Currently, so-called rapid bioassays are still very time consuming and in vitro, or proximate-analysis based systems, take at least 48 hours to complete.

The principle of NIRS was developed thirty years ago. NIRS is a non-invasive spectroscopy method that uses the near-infrared region of the electromagnetic spectrum (from about 800 nm to 2500 nm). Because most feed ingredients are opaque, NIRS uses reflectance of light instead of transmittance through the sample. NIRS does



not require chemical reagents; do not produce fumes or waste products (Picture 1). NIRS provides a fast, relatively inexpensive and safe means to estimate total and available nutrient contents in feed ingredients and feeds (Leeson et al., 2000).

Near infrared reflectance spectroscopy is routinely used for evaluating nutritional quality for a wide range of feed ingredients, including cereal grains and oilseeds.

2.4. ábra - Picture 1. Near infrared reflectance spectroscopy

The disadvantages of NIRS are the initial capital cost of equipment and the effort required for equipment calibration. The usefulness of NIRS depends entirely on careful and conscientious calibration of the equipment. The accuracy of conventional analysis methods that are used as references in NIRS calibrations is extremely important. The number of samples required for NIRS calibration will vary with the feed ingredient component or characteristic that is to be quantified, the nature of the samples and required accuracy (Leeson et al., 2000).

This quick method can be used in feed industry, in feed analytical lab, in the research and also in plant breeding to test the new hybrid lines.

5. Test questions:1. List and characterize the chemical composition of feed according to Weende (proximate) analysis.

2. Describe the van Soest method briefly.

3. Characterize the non-starch polysaccharides (NSP).

4. Describe the NIRS technique.

6. Recommended readingHolme, D.J., Peck, H. 1998. Analytical Biochemistry. Addison Wesley Longman Limited, New York, USA.

Kellems, R.O. and Church, C. D. 2010. Livestock feeds and feeding. Prentice Hall, USA.

McDonald, P., Edwards, R.A., Greenhalgh, J.F.D., Morgan, C.A., Sinclair, L.A., Wilkinson, R.G. 2011. Animal nutrition, Seventh edition. Pearson Education, Limited. Harlow, UK.

Moughan, P.J., Verstegen, M.W.A., Visser-Reyneveld, M.I. (Eds). 2000. Feed evaluation: principles and practice. Wageningen Pers, Wageningen, NL.


3. fejezet - 2. THE DIGESTIVE TRACT AND ITS FUNCTIONS1. 2.1. DIGESTIVE CHARACTERISTICS OF FARM ANIMALSThe nutrients, which are taken up from the feed by the animals, provide the matters for living and producing. In order to utilise the feed the animal has to digest it first and after the absorption it has to be transported for the location where it will be utilised. The digestion itself means the preparation of the nutrients for absorption, because the form in which the animal takes in the feedstuff is not suitable for absorption. In order to this, the animal prepares the feed mechanically and chemically (Rook and Thomas, 1983).

Mechanical preparation: the animal uses several kinds of mechanical preparation. The simplest and most common type is chewing, which makes the larger pieces smaller thus helping the digestion of the feed. Such process is the rumination of the ruminants, which is the muscle contraction of the forestomach and the regurgitation of the feed, or in case of birds the operation of the gizzard, in which in order to improve the mechanical effect grits can be found (crocodiles swallow larger pebbles).

Chemical effects: in addition to the mechanical preparation the different chemical effects are also very important which enables the nutrients to transform into absorbable forms. The hydrochloric acid, which can be found in the stomach, has the same effect and the bile, which has an important role in fat digestion, or myriad of specific enzymes, which have the primary function of the breakdown of the nutrients (Fuller, 2004).

After the digestion, the preparation of the nutrients, takes place the absorption. This case the accordingly small molecules are passing through the intestinal walls and through the blood and lymph circulation they reach the point of use. The efficiency of digestion and absorption depends on the many factors. These factors relate to the animal and the consumed feed.

Factors related to animals: the feed utilisation depends on the species of the animal (structure of digestive apparatus), age (the younger animal utilise better the feed), the type of animal production (dairy or beef cattle).

Factors related to feeds: in the case of feed the most important influencing factor is the composition of the feed, but also important the feed portion’s size and the and the feeding intensity (the more the animal consumes the utilisation is the lower), or the different treatments of the feeds, which may result the improvement of nutrient’s digestibility (starch extruding, expansion).

From the digestion’s point of view the most distinctive difference is the different type of stomach of different species. We can isolate three groups based on their stomach type.

Animals with polygastric stomachs: two major animal groups involved in here, ruminants and poultry but when we talk about this mainly we think of ruminants, but poultry also have a complex stomach type (glandular and muscular stomach) but their digestion rather resembles to digestion of monogastric species. In ruminants before the real stomach (abomasum) there is a forestomach which consists several parts (rumen, reticulum, omasum), which are connected (Figure 6). The pH of the forestomach is nearly neutral 6.4-7.6, which is very important because a lot of bacteria live in here in symbiosis with the animal. This amount of bacteria enables the effective utilisation of the large amount roughage (fibre) in contrast with higher animals the bacteria is able to digest the different polysaccharides.

3.1. ábra - Figure 6. The polygastric stomach of the ruminants


2. THE DIGESTIVE TRACT AND ITS FUNCTIONS

Monogastric animals: among the farm animals pigs and horses are belong to this group. The characteristic of the stomach type is that though it has one interstice the circumstance are different within the interstice (variable pH: 2.7-5.3) due to which bacteria can be found where the value of the pH is higher (Figure 7).

3.2. ábra - Figure 7. Stomach of pig and horse

In case of monogastric animals the contents of the stomach stratify, which can be due to the fact that in these animals the muscle in the stomach is relatively weak thus it is unable to mix homogenously the stomach contents.

Animals with simple stomach: from the farm animals only a few species have this type of stomach (rabbits and fur animals) but if we take in count the hobby animals (dog, cat) the importance of it increases. Finally, we should not to forget that stomach of the human is also belonging to this type. The stomach is characterised by a very muscled stomach wall, which makes able to mix the stomach content homogenously (Frandson et al., 2009).

Regardless from the type of the stomach the digesting apparatus can be divided into three, large, well distinguishable parts. Fore gut, middle gut and hind gut (colon). Apart from the gastrointestinal tract the function of digestion is supported by many other organs. The function of the pancreas is to produce various digestive enzymes, the bile via the bile acids supports the digestion of fat and the liver with various functions which help the digesting process.

Parts of the foregut: oral cavity and its parts (teeth and tongues or beak in case of birds), pharynx, oesophagus (crop of the birds), stomach

Parts of the middle gut (small intestine): duodenum, jejunum, ileum hind gut (large intestine) cecum, colon and rectum.

This division can be found in all farm animals but of course their role in digestion is different in case of different animal species which can be clearly seen from the portion if we correlate the length of intestinal tracts.

3.3. ábra - Table 4. The relative capacity of the different parts of digestive apparatus at different animals



The table clearly shows that in case of ruminants due to forestomach the percentage rate of the stomach is quite large (2/3 of the total capacity), which indicates the importance of the bacterial digestion (Table 4). As a result of this these animals utilise effectively the roughage with high fibre content. The volume of the horse’s stomach is smaller than which we have to take in count when feeding it (Hintz and Cymbaluk, 1984). The horse also digests well the fibre with the help of the bacteria, but the digestion of the fibre does not happen in the forestomach but in the increased cecum and in the colon. The predators (cats and dogs) also have large stomach, but this has a completely different function than the ruminants’. While in ruminants the large stomach is for the bacterial digest of the hardly digestible feed which arrives continuously in large amount, while in the predators the large stomach is for the acceptance of the large amount of available prey, since the prey acquisition is not certain so these animals may remain without food for several days. Therefore it is important if they are able to catch the prey they have to consume from it the more. The typical feature of the human digestive system is the particularly long small intestine. The characteristic of the small intestine is that the absorption of the nutrients begins here, and even there are nutrient groups which exclusively absorbed in the small intestine (proteins). The fact that the small intestine is this large might be because of the omnivorous character of the human.

2. 2.2. FUNCTION OF THE DIGESTIVE SYSTEM OF MONOGASTRIC ANIMALSThe basic principles of the monogastric digestive systems with simple and compound stomach are very similar to each other, so we discuss them together. The characteristics of each species will be discussed later. In monogastric species the mouth has a paramount role. First of all these animals have strong teeth thus they carry out serious mechanical grinding, secondly the chemical digestion begins via saliva. The amount of saliva may differ within different species. While swine and horse produces a relatively large amount of saliva the poultry produces specifically small amount (Champ et al. 1983). Different enzymes can be found in the saliva of different species (swine, rabbit – ptyalin, human, horse –amylase), but they are common in that these enzymes play role in starch digestion (Zang et al., 2002). The effective breakdown of the starch is very important for every animal, because in feeding it has a paramount importance through supplying energy. The saliva has not only role in chemical digestion, because of it the feed becomes slippery due to this it is easier to swallow. From the oral cavity the feed goes through the oesophagus to the stomach, where the conditions are different according to the type of the stomach, but mainly acidic conditions prevail. Primarily a hydrochloric-pepsin digestion takes place in the stomach. The strong highly causative effect of hydrochloric acid breaks down every component of the feed while pepsin, which is specifically a proteolytic enzyme, helps the effective digestion of protein. In the stomach of the horse and pig apart from the previous processes there are also bacterial carbohydrate breakdown but the extent of it is not dominant. From the stomach the feed passes to the small intestine, where the enzymatic breakdown continues, and in addition absorption processes also begin. In fact there are nutrient groups (proteins) which are exclusively absorb in the small intestine. The basis of the enzymatic breakdown is the epithelial cells of the small intestine are able to produce almost all kind of the breakdown enzymes (all of them, except the lipase which is responsible for breaking down fat, and it is produced by the pancreas). Various enzymes are responsible for the breakdown of the nutrients. Below we rehear some of them:

Proteolytic enzymes: trypsin, chymotrypsin, carbopeptidase, chatepsin, chitinase, rennin (in young animals),



lysozyme (bacterial enzyme), erepsin. Basically we know a lot of proteolytic enzymes. The species and the age determine which can be found in the animal. While some proteolytic enzyme is associated with particular animal species, while other enzymes are only operate in a certain growth period.

Carbohydrate-degrading enzymes: ptyalin, α-amylase, lactase, maltase, sucrose. The carbohydrate degrading enzymes are characterised by specificity. A particular enzyme is only capable for breaking down only a certain enzyme.

Lipolytic enzymes: in contrast with the previous two types of enzymes, there is only one kind of lipolytic enzyme, and this is the lipase. Only the lipase is able to break down enzymatically the different lipids, although the different bile acids, which are produced by the bile, can help for the lipase with increasing the efficiency of different decomposition processes.

The efficiency of the chemical digestion processes can be said to be quite good thanks to the large amount of enzymes produced in the intestinal tract plus the enzymes, which are produces by the pancreas and excreted to the small intestine. For the enzyme production in the small intestine, the slightly alkaline environment is the most optimal but the feed (Tang et al., 1999), which is outgoing from the stomach, is highly acidic. In order to avoid this problem, different glands in the small intestine produce an exudates, which have pH 7.5-8.5 and this compensates the acidic stomach content. From the small intestine the feed passes to the colon, where a smaller or large bacteria population lives depending on the animal species. While for some species the digestion processes in the colon do not change the efficiency of feed utilisation (chicken, turkey), while in other species thanks to the vibrant bacterial life serious digestion processes take place (rabbit, horse). Thanks to the bacteria, the fibre content of the feed is converted into volatile fatty acids, which provide energy for the animal. In the hindgut there is a large amount of protein, which is produced because of the dead bacteria, but unfortunately this is no longer available for the animal, so it is can be utilised only by bacteria. The produced excess is excreted from the animal with the faeces.

2.1. 2.2.1. Digestive characteristics of horseIt is very typical of the horse is the thorough mastication of the feed. The horse consumes a kilogram of oats with 800-1400 chewing movements, which can take 10-20 minutes. Due to the great number of chewing movements, the horse produces a large amount of saliva (30-40 litres of saliva daily depending on the feed). The saliva of the horse contains only a small amount of amylase (Moeller et al., 2008), and due to this the digestion of the feed starts already in the oral cavity, with the breakdown of the starch (the human saliva has more than 100 times larger quantity of amylase). From the mouth the feed goes to the quite

small stomach, where the pH is slightly acidic (about 5pH). Due to the small size of the stomach the horse is able to consume only a small amount of the feed. The total gastric emptying time is 3-4 hours, during which time due to the weak stomach muscles the feed stratifies. Because of the slightly acidic stomach the protein digestion of the horse is less effective compared to other animal species, but due to the pH value about 5, in some parts of the stomach bacterial breakdown of starch and fibre take place. The horse is not able to vomit since the opens easily. From the point of view of nutrition this is a very important information, since the absence of vomiting, the overfilling the stomach of the animal can bursar, which can cause death. The feature of the small intestine is that the bile acid, produced by the bile, is continuously discharged to the small intestine, since the horse has not got gall bladder. The most typical digestive characteristic of the horse is the enlarged cecum and colon (60-65% of the total digestive tract), where the bacterial digestion takes place. As a result the horse utilises very well the high fibre content roughage. It also helps the bacterial digestion that the passage rate of the feed slows down in the tract of hindgut and the feed can spend even 36 hours here due to which the bacteria have enough time to digest the hard-degradable fibre constituents.

2.2. 2.2.2. Digestive characteristics of the pigOne of the most important properties of the pig is that it is anatomically omnivorous which is clearly shown by the length of the small intestine which reaches the 1/3 of the full length of the digestive system. Among the farm animals this is the greatest value. As time went by, the length of the digestive system shortened due to the domestication and the intensive rearing further increased the shortening. Among the farm animals, the digestive system of the pig is the most resemble to the human’s. The animal takes in the feed with the lips, incisor and canine teeth, and in natural conditions it chews thoroughly with the well developed teeth. Because of the increment of the stocking density, the animal instead of the thorough mastication bolts it down. The digestion begins with the starch degrading enzyme, the ptyalin, which can be found in the saliva. From here the feed goes



to the single interstice compound stomach, where the feed stratifies, just like in case of horses, because the muscles of the stomach’s wall are not strong enough to stir the whole stomach content. In contrast with the horse, the stomach of the pig is relatively large, so the animal is able to consume a larger amount of feed. In the hindgut bacterial digestion takes place. The older is the animal, the larger is the role of the bacteria. This entails applying that the fibre digestion improves with the age (Jin et al., 1994).

2.3. 2.2.3. Digestive characteristics of rabbitJust like the horse the rabbit also chews a lot, it makes up to 120 chewing movements per minute. In the saliva, ptyalin enzyme can be found (similarly to pigs). From the oral cavity the feed goes into the single stomach, where the pH is highly acidic (pH 2.0-2.2). Among the farm animals the rabbit has the most acidic stomach. In the hindgut moderate fibre breakdown occurs (the efficiency of it is barely 1/3 of the ruminants’). The specific feature of the digestion of the rabbit is the caecotrophy (Hörnicke, 1981). This means the consumption of soft faeces. The consumption of soft faeces begins on the third week after birth, when the changeover for solid feed happens. The organism of the animal separates the two types of faeces by the wave-like movement of the intestine and at dawn the animal simply sucks out from its anus the 5-10 globules mainly in the dark period of the day (Jilge 1980.). In parallel with this the stomach of the animal starts to produce special lysozyme enzymes which degrades the dead bacteria with a very good efficiency. There are very significant differences between the two faecal materials.

The composition of the soft and normal faecal material

It is can be seen from the table that the protein content of the soft faecal material is almost the double of the normal faeces material’s ,and not only the quantity of protein is different, but also the quality is different (Table 5).

3.1. táblázat - Table 5. Chemical composition of the different faeces of rabbit

Soft faeces (%) Hard faeces (%)

Crude protein 15,4 25,7

Crude fiber 30,0 17,8

Crude fat 3,0 5,3

N-free extracts 37,9 36,0

While the normal faecal material contains proteins that the animal could not digest previously, basically the protein content of the soft faeces is from the dead bacteria, which has an excellent amino acid set. This type of the protein covers the third of the protein requirement of the rabbit. The fibre content is only the half of the soft faeces, which provides already a better digestibility, while the fat content is double, which increases the energy content. It is also a very important difference that due to the large amount of bacteria the soft faeces contain almost all of needed vitamin B groups.

2.4. 2.2.4. Digestive characteristic of poultryThe poultry takes in the feed by the beak. There are no teeth in the oral cavity so they are unable chop the feed and to make a mouthful. It is also typical that their sense of taste and smell is very immature (Lindenmaier and Kare, 1959), so we do not have to care about the smell and the taste of the feed, in contrast with other animal species (swine, cattle), for whom these factors are very important. In the mouth there is a minimal saliva production which contains very small amount of amylase enzyme. The galliformes the feed after the oral cavity goes to the crop, which specifically can only be found in some birds. The primary role of the crop is to store and soften the feed, although in some species (pigeons) the crop contains bacteria, which help the digestion of the feed (crop milk). The water fowls do not have crop, but their expandable oesophagus performs with the same function. The goose and the duck can be stuffed which results in the world famous goose or duck liver. It is a very important product so it has got a history not only the animal breeding but in the animal nutrition also. Already in the middle of the 19th centuries some scientific article had been written about the goose stuffing



(Flock et al., 1937).

The poultry have polygastric compound stomach (glandular and muscular stomach) but their digestive processes are completely different from the ruminants, and it is much more similar to the monogastric animals. The stomach builds up from two parts, the glandular stomach and the gizzard (muscular stomach) (Rose, 1997). The feed first goes into the glandular stomach, where it stay for a little time just enough to mix with the stomach excretion with hydrochloric acid and pepsin. From here the feed passes to the gizzard which has very strong muscles, with the help of the grits, which can be found here, in addition to the chemical reactions there is very strong mechanical effect (muscle contraction in 2-5 minutes) applied on the feed, which helps the digestion of it. From the stomach the feed goes to the small intestine, where the digesting processes continue and absorption begins. The poultry is characterised by that though they have a large double cecum the efficiency of bacterial digestion is very low (among farm animals they have the worst fibre digestion except geese). This is traceable to several factors. First of all the feed spend a very little time in the digestive tract (7-8 hours) so there is not sufficient time for bacteria to digest fibre, secondly despite the size of the cecum is large and provides perfect conditions for the microflore, less than 10% of the feed gets here. Because of this the practice says that the digestion of the poultry ends in the small intestine, since in the subsequent gut compartment the absorption is so little which do has no affect on the nutrient supply of the animal.

3. 2.3. FUNCTION OF THE DIGESTIVE SYSTEM RUMINANTSThe most characteristic feature of the digestion of the ruminants is the consumption of large amount of fibre. In order to the indigestible feed become nutrient source for higher animals the gastrointestinal tract of the ruminants went through major changes (mainly the stomach) during the evolution (Hofmann, 1989). Such conditions are stabilized in the rumens of the polygastric stomach that are perfectly suit for the microbes, which in turn have the set of enzymes to digest fibres. This symbiotic relationship is beneficial to all. The microbes get habitat and the mammal get a large amount of digestible nutrient.

The intake of the feed varies within the ruminant species (the cattle graze the grass with the tongue, while the sheep and the goat graze the grass by pressing up it to the upper lips), but the common feature is the absence of the upper incisors. This results in that these animals chew only very superficially, but with the help of rumination the mechanical comminution is very robust.

The saliva production has utmost importance in case of ruminants. In contrast with other farm animal species the ruminants do not have digesting enzymes in the saliva, since the bacteria, which live in symbiosis with the animal, digest anyway the most of the nutrients. The saliva is produced by three different salivary glands: parotid gland, submandibular gland, sublingual gland. These are able to produce even160 litres of saliva daily at cattle, depending on the type of the feed. The saliva is slightly alkaline (pH 7.6-7.8) due to the substances in it (sodium bicarbonate NaHCO3, disodium hydrogen sulphate Na2HSO4) (Ashcenbach et al., 2011). This large amount of slightly alkaline saliva has paramount importance, since it provides the almost neutral conditions for the rumens. This is necessary because the bacteria produce organic acids (acetic acid, propionic acid, butyric acid) even 5-6 kg daily from the different degraded carbohydrates. This acidic affect can be compensated with the slightly alkaline saliva, since the environment with low pH is not suitable for bacteria. In addition the saliva helps swallowing and the access to the feed for the microbes.

The presence of the large quantity of fibre in the feed is necessary to induce the continuous saliva production (in case of dairy 17-18% of the dry matter content should be fibre and for beef this value is 10-12%) (Shaver e al., 1988). However not only the fiber content is important, but also the texture. The saliva production is triggered by the so called structured fibre. If the chaff size is too small (<1cm) despite having the correct fibre content it will not trigger saliva production, the rumen becomes acidic, and this results in reduced efficiency in bacterial digestion.

The large amount feed mixed with saliva gets to the modified forestomach, which consists of three different parts: rumen, reticulum and omasum. These are more than 60% of the total digestive tract. The volume of it is accordingly vast (the size of the cattle’s stomach is 200 litres from which 85% is the rumen). Due to the nearly neutral pH the forestomach provides favourable living conditions for the bacteria. More than 200 bacteria species live in the rumen in one time (Stewart and Jouany 1991) and in every millilitre on average 10 billion. The bacteria digest 60-70% of the feed intake, and use for their life processes. Just one question, why this is good for ruminants? First of all the herbivorous animals large amounts of high fibre content feed and for the



digestion of it the animal does not have the appropriate set of enzymes. The consumed and the degraded carbohydrate based fibre contents are transformed to organic acid by the bacteria, which is available for the animal and becomes to an energy source. It is also important that the dead bacteria while passing through the digestive tract provide protein with excellent amino acid set for the animal (the 30-35% of the protein need of the cattle is provided from bacterial protein, depending on the production), which absorbs in the small intestine. The bacteria not only provide protein but also excellent sources of vitamins. The bacteria are able to produce almost every kind of vitamin B, so the vitamin supply of the ruminants is much easier, than in case of other species.

4. 2.4. FUNCTION OF THE DIGESTIVE SYSTEM OF SUCKLING (YOUNG) ANIMALSThe digestive characteristics of the species discussed above regard for adult animals, but this knowledge cannot be applied for the new-born animals. Depending on the species it takes a lot of time until the animal consumes and digests like it is typical in the species. In case of mammals the initial digestion of monogastric and polygastric animals are very similar. Typically the enzyme production is incomplete, and they are only able to utilise the nutrients of the milk. For every mammal the first feed is milk, so regardless from the species, the primary task of the organism is to digest milk the most effectively. Basically the animal has to digest three kinds of nutrients:

Lactoalbumin: it is digest by different enzymes depending on the species. For lamb and veal the most important enzyme is rennin, which is produced in the abomasum. The rennin precipitates the protein of the milk, and this is degraded by chymotrypsin which is produced by the pancreas. For swine the chymotrypsin also plays an important role. In other species the trypsin is also important proteolytic enzyme.

Lactose: to digest the sugar content of the milk lactase enzyme is need for the animals. This carbohydrate degrading enzyme which is produced in large amounts by every newborn animal, and continuously produce until it consumes milk (Büller et al. 191). With the elimination of milk consumption, the production of it also stops.

Milk fat: the digestion of the milk fat is a priority, not only because it contains the most energy it is also a very important source of essential nutrients. The breakdown of the fat is only performed by the enzyme lipase, which is produced by the pancreas in adult animals, and it also can be found in the saliva of young animals.

Initially the newborn animals are only able to digest the three matters mentioned above, but it is well known that later they will be able to consume feeds containing other kinds of nutrients as well. Among these particularly important the easily or medium soluble carbohydrates, the digestion of these begins when the animal is 3-4 weeks old. The digestion of hardly soluble carbohydrates and the fibres occur last. The ruminants have to be 5-6 weeks old to digest the fibre in some kind of way, while the flora of the rumen complete formation and the effective fibre digestion can be expected in the 3rd and 4th month.

5. Test questions:1. What are the roles of the bacteria in the rumen?

2. Describe the features of the digestion of horse?

3. What are the differences between the soft and the hard faeces at rabbits?

4. What do you know about the digestion of poultries?

6. Recommended readingHolme, D.J., Peck, H. 1998. Analytical Biochemistry. Addison Wesley Longman Limited, New York, USA.


McDonald, P., Edwards, R.A., Greenhalgh, J.F.D., Morgan, C.A., Sinclair, L.A., Wilkinson, R.G. 2011. Animal nutrition, Seventh edition. Pearson Education, Limited. Harlow, UK.



Moughan, P.J., Verstegen, M.W.A., Visser-Reyneveld, M.I. (Eds). 2000. Feed evaluation: principles and practice Wageningen Pers, Wageningen, NL.


4. fejezet - 3. THE METABOLISM OF NUTRIENTS IN MONOGASTRIC AND RUMINANT ANIMAL1. 3.1. PROTEIN AND AMINO ACIDS1.1. 3.1.1. Chemical structure and properties of proteinProtein, highly complex substance that is present in all living organisms. Proteins are of great nutritional value and are directly involved in the chemical processes essential for life. All cells contain protein and a rapid cell turnover occurs. Consequently, it is essential to provide replacement protein from the diet to meet turnover requirements in all kinds of animals. In addition to protein needed for repair, protein is necessary for growth and formation of animal product (meat, milk, eggs).Without protein synthesis life could not exist. Thousands of different proteins occur in various tissues.

The protein content of animal organs is usually much higher than that of the blood plasma. Muscles, for example, contain about 30 percent protein, the liver 20 to 30 percent, and red blood cells 30 percent. Higher percentages of protein are found in hair, bones, and other organs and tissues with low water content. Evidently, protein molecules are produced in cells by the stepwise alignment of amino acids and are released into the body fluids only after synthesis is complete.

Except in animals whose intestinal microflora (microbiota) can synthesize protein from nonprotein nitrogen sources, protein or its constituent amino acids must be provided in the diet to allow normal growth and other productive function.

The proteins are long chains of amino acids. The amino acids contain one carboxyl group (-COOH) and at least one amino group (-NH2) in the α-position according to the general formula:

Proteins can be classified as follow:

1. Simple proteins which yield only amino acids on hydrolysis.

2. Conjugated proteins which are simple proteins combined with non-protein compounds. The term of non-protein compound is referred to as the prosthetic group.

Simple proteins can be divided into two groups on the basis of their structure, globular and fibrous protein.

Globular proteins: these are relatively soluble and are quite compact due to the large amount of folding of a long polypeptide chain. Biologically active proteins belong to this group, such as enzymes, protein hormones and oxygen-carrying proteins.

Fibrous proteins: these are composed of long peptide chains connected by several types of cross-ulinkages to form a stable and rather insoluble structure. This type of proteins is responsible for the mechanical properties of many animal tissues and organs in the form of collagen, elastin and keratin.


3. THE METABOLISM OF NUTRIENTS IN

MONOGASTRIC AND RUMINANT ANIMAL

A large group of proteins has been called conjugated proteins, because they are complex molecules of protein consisting of protein and nonprotein moieties. Conjugated proteins can be subdivided into mucoproteins, which, in addition to protein, contain carbohydrate; lipoproteins, which contain lipids; phosphoproteins, which are rich in phosphate; chromoproteins, which contain pigments such as iron-porphyrins, carotenoids, bile pigments, and melanin; and finally, nucleoproteins, which contain nucleic acid.

The production of proteins is regulated by the genetic materials contained in the nucleus of the animal’s cells. Deoxyribonucleic acid (DNA) is the genetic material of life. DNA exists in the well known form of the double helix, and uses the same, universal genetic code that allows it to be translated into proteins. It is found in all live organisms, and it holds the genetic information that each organism uses to produce the proteins necessary for life. Wherever it is found, whether in prokaryotic or eukaryotic cells, DNA exists in the iconic form of the double helix, and uses the same, universal genetic code that allows it to be translated into proteins. DNA controls all protein synthesis occurring in the animal body. The processes of producing proteins from DNA, known as transcription and translation, are also virtually the same in all organisms: DNA is transcribed into RNA, which is then translated into the amino acid sequence of a polypeptide. There are many details to these processes, including the enzymes that are utilized, the ways in which organisms control the processes, and modifications that must be made to polypeptides before they become active proteins.

If for some reason adequate amounts of amino acids are not being provided to the animal, the cells cannot produce protein. The amino acids required for cellular protein synthesis are supplied in the diet or result from digestive processes occurring in the gastrointestinal (GI) tract.

Most proteins found in plants and animals are composed of only 20 amino acids. The primary difference between plant and animals with respect to their amino acid requirements is that plants are able to synthesize all required amino acids from inorganic nitrogen sources; however, the higher animals are unable to do so. Therefore, a dietary source of amino acids must be provided for most animals.

1.2. 3.1.2. Digestion of proteinMonogastric animals

During digestion the dietary proteins are broken down by pepsin and hydrochloric acid into large polypeptides, with only small amounts of free amino acids being liberate. Protein molecules resistant to the action of the stomach, together with large peptides fragments resulting from peptic digestion, enter the duodenum to be further hydrolyzed in alkaline medium by pancreatic enzymes. These enzymes release small peptides and large amounts of free amino acids. The small peptides become hydrolyzed by the action of peptidase secreted from the pancreas and peptidases that are present in desquamated mucosal cells. The brush border membrane fulfils a double function, in absorbing amino acids and peptides and in enzymatic hydrolysis of small peptides to free amino acids.

To summarize it can be stated that during the digestion process the amino acids and peptides are absorbed into the body and are used to build new proteins such as muscle (meat).

Ruminants

Dietary protein is fermented by rumen microbes. The majority of true protein, and non-protein nitrogen (NPN), entering the rumen is broken down to ammonia, which bacteria require for synthesizing their own body protein. According to the research data, ammonia is most efficiently incorporated into bacterial protein when the diet is rich in soluble carbohydrates, particularly starch. Ammonia, in excess of that used by the micro-organisms, is absorbed through the rumen wall into the blood, carried to the liver, and converted to urea; the greater part is excreted in the urine. Some urea is returned to the rumen via the saliva, and also directly through the rumen wall.

The undegraded true protein fraction, plus the microbial (microbiota) protein, passes from the rumen to the abomasum, where it is digested, and absorbed into the bloodstream through the walls of the small intestine.

1.3. 3.1.3. Classification of amino acidsThe dietary amino acids can be subdivided into three categories: essential amino acids (or non-dispensable), semi- essential amino acids, and non-essential amino acids (or dispensable).




Essential amino acids are those that the animal cannot produce in adequate amounts to satisfy its requirements.

Non-essential amino acids are those that the tissues of that animal can synthesize in adequate amounts.

Semi-essential amino acid has a loose definition but generally refers to any amino acid that has the capacity to be both essential and non-essential at once. This means that any amino acids that are not essential to the diet because the body can synthesize their molecules from other amino acids.

The classification of amino acids is summarized in Table 6.

4.1. ábra - Table 6. Classification of amino acids (Boisen, 1997)

If a specific amino acid required by an animal to synthesize a protein is not available, the protein cannot by synthesize. These amino acids referred to as a limiting amino acid.

Ruminant animals and some herbivores do not have the same dietary requirements for amino acids as do monogastric species. The reason is that the microbial population in the GI tract,

primarily in the rumen and large intestine, synthesizes microbial protein, which can then be digested and thus provides amino acids.

1.4. 3.1.4. Disorders in protein supplyIn amino acid nutrition the following three different main disorders are known:

Amino acid imbalance is the term commonly used to designate a relative deficiency of an essential amino acid resulting from an excess of one or more amino acids in the diet.

Amino acid antagonism refers to growth depression caused by ingestion of a surplus of one amino acid which can be overcome by adding another, structurally similar amino acid. Excess lysine causes a growth depression that in chicks, can be reversed by additional arginine. Antagonism differs from imbalance in that the supplemented amino acids need not be limiting (Herper et. al., 1970).

Some amino acid antagonism can be seen below:

Lysine<----------------------> Arginine

Leucine<--------------------> Isoleucine

Isoleucine<------------------>Valine

Isoleucine<------------------>Phenylalanine

Phenylalanine<------------->Threonine

Phenylalanine<------------->Valine




Amino acid toxicity is seen when the adverse effect of an excess amino acid cannot be overcome by addition of another amino acid. Ingestion of methionine, tyrosine or tryptophan in large amounts, up to about two or three times the requirement, is followed by serious irregularities apart from growth depression.

1.5. 3.1.5. Nutritive value of protein sourcesThe biological evaluation of dietary proteins is very important to compare the different protein sources and also to substitute protein sources in the diet on the proper way.

Biological evaluation of proteins often preferred on the basis of amino acid analysis since results of biological assays reflect the ability of feed proteins to covert of body protein.

However, it should be noted that biological efficiency of dietary protein utilization depends not only on balance of available amino acids, but also on the nitrogen and energy intake as well. Moreover, the species of animal and its physiological and health status could also play an important role in biological efficiency of dietary protein utilization.

Various evaluation methods are known. The most important methods are the followings:

Biological value (BV)

According to Thomas and Mitchell (1909) BV can be defined as the proportion of absorbed nitrogen to the digested nitrogen:

BV= (N retained (g)/ N digested (g)) x 100

The BV value can be determined by balance trial in which the N intake and the N excretion via faeces and urine are measured.

The BV value of a protein source can be calculated based on animal trial as follows:

It should be noted that this formula provide values of protein for growth purposes only.

However, the more precise determinations also take account of maintenance and growth by making corrections for metabolic and endogenous losses of nitrogen.

The biological value of selected feeds for growing pigs can be seen in Table 7.

4.2. ábra - Table 7. Biological value (BV) of selected feeds for growing pigs (Armstrong and Mitchell, 1955)




In addition, it is noteworthy, that whole-egg protein has a BV of about 100, meat proteins range from 72 to 79, cereal proteins 50 to 65%.

The BV value of dietary protein source depends on two main factors:

1. Efficiency of conversion of protein into amino acid in GI;

2. How the amino acid balance compares with the amino acid requirement of the animal.

1.6. 3.1.6. Protein efficiency ratio (PER) and net protein utilization (NPU)Other measures of protein quality are the protein efficiency ratio (PER) and net protein utilization (NPU) or net protein value (NPV).

PER is defined as the number of grams body weight gain of an animal per unit of protein consumed. This value is obtained from feeding trial with laboratory rats, but the same calculation can be made for any animal species fed different protein sources.

NPU measures efficiency of growth by comparing body N resulting from feeding a test protein with that resulting from feeding a comparable group of animals a protein-free diet for the same length of time.

NPU can be calculated according to following formula (Miller and Bender, 1955):

Net protein utilization of selected plant and animal protein sources is summarized in Table 8.

4.3. ábra - Table 8. Net protein utilization (NPU) of selected plant and animal protein sources (After Miller and Bander, 1955; Johson and Coon (1979




Test questions:

1. Characterize the protein and amino acids briefly.

2. Describe the process of protein digestion in monogastric animals and in ruminants.

3. Give the classification of amino acids.

4. Which are the most important methods to characterize the nutritive value of protein sources?

Recommended reading

Babinszky, L. 2008. The concepts of ileal digestible amino acid and ideal protein in swine and poultry nutrition. In: Fekete, S. Gy. (Ed): Veterinary Nutrition and Dietetics. Chapter VII: Digestibility of nutrients. „Pro Scientia Veterinaria Hungarica” Budapest. 119-146.

D’Mello, J.P.F. (Ed). 2002. Amino acids in animal nutrition. CABI Publishing, Wallingford, UK.


McDonald, P., Edwards, R.A., Greenhalgh, J.F.D., Morgan, C.A., Sinclair, L.A., Wilkinson, R.G. 2011. Animal nutrition. Seventh edition. Pearson Education, Limited. Harlow, UK.


2. 3.2. LIPID (FATS)In animal nutrition, the nomenclature of the lipids is significantly different than the chemical name. The term lipid is a collective one used for a wide variety of substances that vary from simple, short-chain fatty acids to large very complex molecules.

The crude fat content of the feed is one of the most important fundamental data for animal nutrition, because the fats contain the most energy (2.25 times higher than the carbohydrates) (Miller, 1979).

In the animal body the fat has got a lot of different roles:

• Energy supply




• Storages energy in different places in the body (under the skin, among the muscles, in the liver, abdomen spaces)

• Fat supports bone formation, solidifies the bones and teeth of juveniles.

• It became known that fat has a specific action that it promotes the incorporation of protein.

• Helps in the absorption of vitamins, and mineral elements

• Defends the inside organs

• Helps to keep on the permanent temperature at the hot-blooded animals

• Binds the toxic matters

• Determinates the water balance

• Fat usually improves the palability of the feed, which has a considerable economic advantage

• The more fat the feed contains, the more easy to granulate

• Feeding with forage which have sizing or was not pelleted correctly the fat reduces dust formation

The fats are determined by the air dry grids feed which is extracted for approx. 8 hours with petrol-ether in Soxhlet’s apparatus. This extract is the crude fat what is also called lipids. The compounds belonging mentioned above can be divided into 3 groups:

a. simple glycerides

b. complex glycerides

c. lipids without glycerol

Simple glycerides

The simple glycerides group include fats (in animal nutrition: real fats), which are esters formed by fatty acids with glycerol, an alcohol with three hydroxyl groups. The reason of the high variability of plant and animal fatty acid is that the fatty acids, which are connecting to the glycerol, may differ in the number of carbon atoms and saturation, and in the three fatty acids, which are in the fat molecule, don’t have to be the same (homoacid fats), also they can be different from each other in chemical composition (heteroacid fats).

The number of the carbon atoms in chain is a very important factor.

The saponification number can show us the length of the fatty acid. In the next tablet it can seen the saponification numbers some different fats (Table 9).

4.1. táblázat - Table 9. The saponification numbers of different kind of fats (Church and Pond, 1988)

Fat Saponification number

Beef tallow 196-200

Pig fat 195-203

Butter 210-230

Coconut fat 253-262




Corn oil 187-193

Line oil 188-195

Soy oil 189-194

Sunflower oil 188-193

Between the fats and oils the only different is in their physical state. The oils are liquid at room temperature, and the fats are solid. The physical state is influenced by the number of double bonds in the fat. The more double bonds mean the fat get liquid form on a lower temperature also. The index what can show the quantity of the double bonds is the Iodine number. Iodine will unite with double bonds of the unsaturated fatty acids in fats, each double bond taking up two atoms of iodine. The iodine number thus is a measure of the total amount of unsaturation fatty acids in a fat. Vegetable oils, and fish oils which are highly unsaturated, thus have high iodine numbers, while beef tallow, coconut oil, butter, which are highly saturated have low iodine numbers (Table 10).

4.2. táblázat - Table 10. The iodine numbers of different kind of fats (Church and Pond, 1988)

Fat Iodine number

Beef tallow 35-40

Pig fat 47-67

Butter 26-38

Coconut fat 6-10

Corn oil 111-128

Line oil 175-202

Soy oil 122-134

Sunflower oil 129-136

Complex glycerides: the complex glyceride’s (complex lipid) chemical constructions very similar to the simple glycerides, but they are different in that they are containing other components as well, not just fatty acids. As they have a minor quantity in feed, they are not important as an energy sources, but physiological function.

The most important is the phosphglycerides in this compound group, in which construction phosphoric acid is also involved. Nitrogen-containing phosphatides are lecithin and cephalins, mainly know as membrane components of muscle and nerve cells. In practiced feeding lecithin is used as fat emulsifier. The phosphatides can be found in every living cell of the animal organisms, where they not just have an important role in structure, but also in metabolism.

Glycolipids are also complex glycerides. It contains not just only fatty acids but carbohydrates (glucose or galactose) also take part in the glycolipid construction. They are very wide spread among plants. They provide the 60% of the green feed’s crude fat content.

Lipids without glycerol: they have a very varied composition. Their common characteristic is that they do not contain glycerol. Waxes are included here. These are esters of long chain fatty acids and a large carbon number alcohol with one hydroxyl group. They have poor digestibility, and even they deteriorate the digestibility of the




overlaid plant materials. In animal organisms they occur in wool and in the uropygial gland of waterfowl (Baker et al. 1982).

Steroids can be found in both flora and fauna. They can be extracted with degreasing agents, but chemically they are not fat: neither glycerol nor fatty acid can be found in them.

They occur in very small amounts, but they have a very significant biological effect: hormones, provitamins, natural detergents,

To the feed’s crude fat content fraction are also belonging the following materials:

The plant pigments can make up a considerable part of crude fat content in green fodders, silages, good quality hays, Their energy content is much less than the real fat’s, thus the energy content of the feed is highly dependent on their quantity. Their presence is recorded in the practical nutrition because they are incorporating to – mainly fat containing - products of animals. The orange colour of the salmon flesh, the yellowish colour of the broiler skin or the bright colour of the egg yolk is preferred, but the yellowish colour of suet (pig fat) is not liked by the meat industry in many countries. The compounds belonging here are carotenoids and their constructional congeners, xanthophylls are the most important materials.

Deficiency symptoms stemming from fat deficiency in feeding are the followings:

• degenerative lesions,

• disorders in growth, , and in milk and egg production

• problems in the reproduction

It is essential to realize that these pathological characterised phenomenons’s eradication will not be succeeded with saturated fatty acids, but with polyunsaturated fatty acids will succeed. It was also proven that some of the latter cannot be synthesized by animal organisms. According to these considerations, for normal metabolism of the farm animals the strictly necessary needed polyunsaturated long chain fatty acids, which animals are not able to synthetise, are called essential fatty acids.

Among them, for practical feeding the most important is linoleic acid (C18:2), because from this the animal organism synthesizes the alone active arachidonic acid (C20:4). Thus the latter can not be found in feed of plant origin, but this is not a problem, because because the animal can freely produce arachidonic acid from linoleic acid in which oily seeds are very rich. Providing farm animals with linoleic acid usually will not cause any difficulty even if animals are not fed with oily seeds, because from the 4-5% of the corn’s oil content 42% is linoleic acid. This means that the average linoleic acid content is 2% of the air dry corn, while the demand of pig and the poultry are ¼-1/3 of this.

The linolenic acid (C18:3) was classified also as an essential fatty acid (Figure 8).

4.4. ábra - Figure 8. The shape of the linoleic acid

This can be converted into eicosapentaeonic acid (C20:5) or docosahexaeonic acid (C22:6). The linolenic acid promotes the absorption of saturated fatty acids, and it also has a beneficial dietary effect. Some degree defiency in essential fatty acids may occur, if fat deficiency is caused by high proportions of poor quality extracted meals and to deal with this, industrial fats are added to the feed, which were treated a variety of way, and mostly lost their double bonds. Deficiency also occurs when in the forage there is wheat instead of corn.




Tolerant for the most fats and required by the carnivores. They are followed by poultry and pigs. The natural diet of ruminant species is low in fat, the stomachs become burden if the daily feed portion contains too much fat. In particular the presence of soft fats is a disadvantage, because they cover the fibrous feed contents and prevent the bacterial degradation. The resulting disadvantages in the rumen (decrease in fiber digestion, narrowing of the acetic acid: propionic acid ratio, decreasing milk fat content) can be avoided with only slightly degradable by-pass fat products.

A part of fat getting into the rumen is partly degraded by microbiological lipase, on the other hand it is degraded by the lipolytic enzymes of the feed. Glycerol and glycolipid are formed through hydrolysis, during the decomposing of these compounds, glycerol and released carbohydrates (glucose, galactose) are fermented in the rumen. A smaller part of the fatty acids are being used by rumen microbes and infusioriums for synthesizing microbial fat. After hydrolysis the unsaturated fatty acids are saturating with hydrogenation in the rumen. The fat, which has passed the stomach of the ruminants are digesting more effective than the monogastric animals.

The feed supplement with fat comes up in case of high yielding dairy cows. This is because the mammary glands are utilising excellently the absorbed fatty acids, and that the increased energy content of the fodder makes possible to reduce the amount of the forage’s portion. Taking all these requirements, the minimum fat demand of the ruminants can be considered as the 2% of the dry matter content. In case of the fat fed contains a lot of unsaturated fatty acids, the fat uptake should not exceed the 4-5% of the dry matter content. Fat containing saturated fatty acids can be more than 6% of the fat content of the dry-matter intake without interfering the rumen’s fermentation processes. A higher amount of fat is only available from by-pass fat products.

2.1. 3.2.1. Digestion of fatsThe most part of the dietary lipids are the triglycerides, so this group is the most important. The digestion of the fat is beginning in the small intestine with the help of the lipase, which is the only fat digestion enzyme. However all the enzymes are made by the small intestine but not the lipase. This enzyme is secreted by only just the pancreatic (Lassitier and Hardy, 1982). The digestion of fats depends on a lot of different factors. The digestion is determinated by the species of the animal (usually all the breeded animals can digest the fat with very good efficiency), the age of the animals, the type of the fat (saturated fatty acids – worse digestion or unsaturated fatty acids – better digestion), the secretion of lipase enzyme and bile and the stomach type (monogastric or ruminant).

2.2. 3.2.2. Rancidity of fatsThe most common alteration of the feed’s fat content is the rancidity. Those rather complex chemical processes that take place simultaneously or sequentially can be divided into two groups: hydrolytic and oxidative alterations.

By hydrolysis, fatty acids are being released from fat molecules. This water using process is accelerated by higher temperature, and the presence of light and heavy metals’ salts. Especially effective catalyser is the lipase which is inside the forage, and it is also produced by the bacteria which are on the surface of the feed. The formed fatty acids are nontoxic, but they may be disadvantageous by irritating the mucous membrane in the mouth and pharynx („scarping flavour”) and it may impair the taste and odour of the feed. Because of it’s practical significance, during the routine examination of feed the fat’s acid number is also determined (Rossel, 1983). The acid number is equivalent with the amount of KOH in mg with which 1g of the fat’s acid content is being neutralized.

The oxidative alterations are occuring because the autooxidation of the unsaturated and polyunsaturated fatty acids. This oxygen user process is catalyzed by the presence of heat and light as well as some micro-elements (copper, iron, manganese). The chemical reaction itself is that the inside the fatty acid’s carbon chain the one of the double bond between the carbon molecules opens and it is replaced by –O – OH – (hydroperoxide formation) and – O – O bond (peroxide formation). The oxygen uptake (and the release of hydrogen) is the explanation for why feed grains are less prone to rancidity than grind which are contact with air with a large surface. The peroxide has a particularly detrimental effect on animal organisms. In the organism and in the forage, peroxide destroys not only just the unsaturated fatty acids but the oxidation-sensitive active ingredients such as vitamin A, D, E, carotene, biotin, etc.

The peroxide content of the feed’s fat can be expressed with the so called peroxide number. The basis for




determining this in laboratory that the excess amount of potassium iodide solution added to the fat, the peroxides are releasing to their proportion iodine from the solution. The peroxide number is nothing else than the number of consumed millilitres from standard sodium thiosulphate solution for the iodine released by 1kg of fat.

The peroxide number alone is not a sufficient parameter to determine how feedable the forage is. It is obvious that the amount of the feed’s fat content should be known, because only with just these two sets of data can be defined that how much of these harmful substances are taken up by the animal. When hydroperoxide and peroxide are oxidize something, while reducing themselves, aldehydes, ketons and organic acids are formed. Some polymerization products may be classified here as well. The latter are considered to be toxic, whereas the formers are not. Each of them contributes on the formation of rancid flavour and odour.

4.5. ábra - Figure 9. Changing the lipid quality during storaging (Schmidt, 1996

Apparent from the foregoing the amount of peroxide in rancidity is not constantly increasing in the feed, but as it can be seen in the figure after reaching a peak value it decreases rather quickly, in contrast with the acid number which is constantly increasing. The Figure 9 also provides an opportunity to take a position in the feed ability of the feed containing rancid fat. When the acid number and the peroxide number are small, the feed is fresh and has a good quality. If the peroxide number is high, the feed should not be fed with any kind of animal. The small peroxide number is coincided with high acid number, if the rancidity process is in a very advanced state. Such feed is characterised by specific rancid taste and odour, and though it is non toxic, those previously contained bio-agents are already inactivate. Therefore it should not be fed in any case with juveniles and breeding animals. It is correct if it is only a small part of less sensitive animals’ daily portion. Rancidity of fats, particularly the peroxide formation, can be prevented by adding different kinds of antioxidants to the feed. There are natural antioxidants (e.g. vitamin E, C, selenium) (Surai, 2002), but the feed industry uses synthetically antioxidant products (EMQ, BHT, BHA, XAX) also (Chen, et al, 1992).

Test questions:

1. Characterize the simple glycerides briefly!

2. Describe the rancidity of fats!

3. What are the roles of the fats in the animal body?

4. Why the unsaturated fatty acids are so important?

Recommended reading

Babinszky, L. 1998. Dietary fat and milk production (Chapter 8). In: The Lactating Sow, Verstegen, M.W.A., Moughan, P.J. and Schrama, J.W. (Eds). Wageningen Pers. 143-157.







3. 3.3. CARBOHYDRATESIf we subtract from the feed’s organic matter content the total quantity of crude protein, crude fat and crude fiber, we get the fourth group of organic nutrients, which are called nitrogen-free extracts (n.f.e.) in the science of animal nutrition. It is a diverse group, even from the feeding’s point of view these compounds do not have the same role. Among them carbohydrates, organic acids, glycosides and alkaloids are mainly important. Moreover regarding their amount carbohydrates are the majority, when we speak about the feed’s nitrogen-free extracts, we foremost think of the carbohydrates. The primary function of this group in animal nutrition is to serve as a source of energy for normal life processes (Church and Pond, 1988).

3.1. 3.3.1. Nitrogen free extractsIt is considered that the Nitrogen free extracts compounds are effective – and in most country – cheap energy-generating products. They are effective because the here belonging carbohydrates are easy to digest. Their effectiveness is slightly moderated in ruminants, because their loss during gastric fermentation is often considerable. This is especially true for sugars: from 1000g beet sugar in ox 188g, in pig 281g fat is being produced. For starch these 2 values are 248g and 355g respectively.

The carbohydrates have got different goals in the animals and the plants. At the animals the goal is very simple: cheap energy source. But in the plants there are a lot of different roles.

• The easily soluble carbohydrates (simple sugars) take apart in the energy transformation and the building up of the plant.

• The most important role of the less soluble carbohydrates (starch) is the storaging of nutrient matters

• The hardly soluble carbohydrates take apart into the strengthen of the plant structure (fiber)

Monosaccharides

Among carbohydrates the monosaccharides can be found in smaller amount directly in the feed (fruits, honey), most of them are temporary intermediate products of higher molecule weight carbohydrates. Sugars with three and four carbon atoms do not have an importance in feeding, from the five carbon atoms sugar (pentoses), the ribose, xylose, arabinose and ribulose should be mentioned. Their role is in the construction of hemicelluloses which were called before pentosans (Saha, 2003).

The sugars containing six carbon atoms (hexoses) basic role in feeding is that starch and cellulose are being condensated form them. Aldose (aldehyde with oxo group) is glucose, galactose and mannose. Ketose (ketone with oxo group) is fructose.

The most important monosaccharide is the glucose. As the amino acid the glucose also has optical isomer forms, the L which is inactive and the D which is active form. It has got two different forms (open carbon chain, and a ring structure) (Jurgens, 2002). At the ring structure we can divide two different spacing form the alpha (α) and the beta (β) form (Figure 10).

4.6. ábra - Figure 10. The different spacing forms of the glucose




The spacing forms and the different isomers are very important at the glucose, because these features can determinate what the glucose is good for.

Disaccharides

The disaccharides – as their name implies – are the product of two monosaccarides. One of the monosaccharide is always the glucose and the other is changing. In contrast with monosaccarides they occur in quite large amount in animal feed.

The most important in the nutrition is the sucrose. The sucrose (beet sugar, cane sugar) is built up by a glucose and a fructose molecule. It gives the sweet flavour of carrot, green maize, sorghum, fruits and sugar cane. It can be found any kinds of vegetable origin feedstuffs. The importance of the sucrose:

• Direct energy source because contains a lot of energy (Raben et al. 2002) (1mol – 29, KJ)

• The energy in the plant is transported in this carbohydrate form

• Prevent the plant against the freezing

The lactose is made up by a glucose and a galactose molecule. Only can be found in the milk of mammals so, this is the milk’s carbohydrate. This kind of energy source is very important at the new-born animals. It is a good substrate for lactic acid producing bacteria in the digestive tract.

If two glucose molecules are connecting to each other we can get different kind of disaccharides depend on the binding places and the spacing forms.

The maltose (1-4α) is one of the most common disaccharides, which contains two glucose molecules – is formatting during the synthesis and breakdown of starch (Niittylä et al. 2004).

Also very important is the cellobiose is formed by two 1-4ß-glucose and it is the basic unit of cellulose chain. The 1-4 binding means that the two glucose molecules have a connection between the 1 and 4 carbon atomic.

Trisaccharides

Among the trisaccharides the only important molecule in the nutrition is the raffinose. It is formatted by glucose, fructose and a galactose molecule. It can be found in the sugar containing fodder plants (sugar beet, lupine, soybean). During the process of sugar industry is very important to process the beet as soon as possible, because in the mid time (harvesting-processing), the sucrose can be transformed continuously to raffinose, which is not fit for the sugar factories. The sugar beet’s raffinose content is enhanced in molasses, because it is perfectly soluble and crystallizes hardly. With the sucrose the main task of the raffinose is hindering the freezing damages of the plants.

Polysaccharides

From polysaccharides the N-free extractable substances are starch, inulin and glycogen. The main task of these matters is storaging the nutrient matters. The most important is the starch, which is a very good energy source both for the animals and humans too. The original function of starch is – just like the same as in plants – the necessary energy storage for vital signs, its feeding role is the same: easy energy source for farm animals which can be digested easily with their own enzymes without microbial contribution. Some kind of plant parts, for example the seeds of cereals contain 50-70%, the potato tuber contains 14-18% starch. It is made up by more than 10.000 pieces 1-4α glucose molecule. The starch is insoluble in water. It has got two different forms, the amylose and the amylopectin. The amylose is look like a spring with 6 glucose molecule (Figure 11).




4.7. ábra - Figure 11. Amylose “spring”

A lot of amylose spring can be connected together and build up the amylopectin form (Figure 12). Every branch in the structure is an individual amylose spring.

4.8. ábra - Figure 12. The shape of the amylopectin

The dextrin is formed from starch by heat when the starch molecule falls apart to glucose chains. Each plant species have a characteristic shape of the starch granule (Figure 13). This is significant in feed analysis (in case of warranty).

4.9. ábra - Figure 13. Different plants, different starch shapes (upper left- potato, lower right- wheat, the other two peas)

Inulin can be found in the tuber of sweet potato, has a sweet taste, and this polysaccharide is condensated from β-fructose molecule. It has the same function as the starch: energy reserve for plants, but the animal organisms utilize it bad efficiency. The inulin also can be found in the onion and the asparagus.

The glycogen is a kind of polysaccharide which is built up by glucose molecules, it only can be found in animal bodies but only just a very small amount (0,5-1,0%). The glycogen is built up from α-glucose molecules and the shape is very similar to the amylopectin. It fills in the role of the quickly mobilised energy reserve (animal starch). It is storaged specially in the liver and muscles. Since the amount of them is small compared with their physiological importance, it is only a minor component even in the meaty-type feed.




NSP (non-starch polysaccharides)

The NSP matters are a very strange group of the carbohydrates. The most important role of the NSP matters is that they are part of the different seed feedstuffs, and they are indigestible directly for the animals. In the nature there are more than 100 different types of monosaccharides can be found but only just a few are building up the NSP matters. The NSP matter doesn’t contain only carbohydrates but a lot of other compounds also.

The NSP matters has an effect on the performance of the animals, the activation of enzymes, the structure of the duodenal mucosa, the microflore of gut, the secretion of different hormones. Because the animals are not able to digest the NSP matters directly the utilization depends on the effectiveness of the microbiological digestion (Bedford, 1996). After the bacterial fermentation, short carbon chain fatty acids can be arose, which will be an energy source for the animal. The average digestion effectiveness of the NSP matters only 30% which is much worse than the digestion of starch or simple sugars (de Lange, 2000). The presence of the NSP matters reduces the digestion of different matters also (protein, fat, starch) (See more about NSP matters in Chapter 1).

Organic acids

The organic acids are forming an independent group of the N-free extracts. Moderate amount of them in the diet is generally preferred, because they promote the development of the beneficial intestinal microorganism populations, and impair the living conditions of the putrefactive and harmful bacteria. It does not shifts the body’s acid-base balance to acidic range, because the absorbed proportion of these compounds latch on to the intermediate metabolism as an energy source, and loses its acidic character. It ha hot two significant sources. Most of them come from the feedstuffs and at the ruminants from the rumen fermentation. The extended exposure of the great amount of consumed organic acids may cause acidosis, because the irritation of the digesting tube’s mucosa the dietetical effect may become unfavourable. The energy content of the organic acids is slightly less than carbohydrates but it can be remarkable at the ruminants. The feed itself contains organic acids (oxalic, malic and citric acids), but the animals can get a higher amount of organic acids from fermented feed. The role of microorganisms in this is dual: they produce organic acids themselves, but they also utilize them as energy source. The organic acids are important not only in the direct feeding but in the feed conservation also. During the silage making the lactic acid is the conservation matter, and some other occasions we can use other organic acids too (propionic acid, formic acid) (Salminen et al, 2004).

Alkaloids and glycosides

The alkaloids and glycosides occur in a very small amount in the feed; their energy supply can be negligible. This small amount is enough to significantly alter the plant origin feed’s taste, odour and dietary effects. The majority of them are toxic (strichin, ricin) or have an anti-nutritive effect, but some of them are not harmful (piperin) and we can find among them a lot of virtuous matters (coffein, quinine, morphine, codeine, opium). If the feeds are containing alkaloids and glycosides can be fed after preparations which are removing or inactivating these substances. Plant breeding can have a significant role in producing alkaloid and glycoside free or low varieties. The alkaloids mainly contain nitrogen and they are not soluble in water. In one plant more alkaloids can be found.

Digestion and absorption of carbohydrates

We have seen before at the fats, that there is only one kind of enzyme for the digestion (lipase). At the carbohydrates this form is not true, because every different kinds of carbohydrates has an own enzyme (lactose-lactase, amylose-amylase, maltose-maltase etc.). It means that the digestion of these group is very variant depends on the type of carbohydrate.

The digestion of the carbohydrates is very diverse at the ruminant and non-ruminant animals. At the non-ruminant animals (like humans) the digestion of the carbohydrates starts in the mouth with the amylase enzyme which can be found in the saliva (Lassitier and Hardy, 1982). This enzyme is able to digest the starch. This process (starch digestion) is a very time demanding, so it is very important to start the digestion as soon as possible if the body wants some energy from the starch. Any kind of carbohydrates can be absorbed only in a monosaccharide form, so the bigger size the slower digestion. The digestion is continuing in the small intestine, by a lot of enzymes made by the pancreatic and the small intestine. The digestion of carbohydrates is finishing in the large intestine, by enzymes and by the bacteria what are living here.

At the ruminant animals the digestion of the carbohydrates is absolutely different than the non-ruminants




animals, because of the microbiological life of rumen (Miller, 1979) but the absorption is the same.

Test questions:

1. Characterize the monosaccharides briefly!

2. Describe the role of glucose!

3. Why the starch is important in the animal nutrition?

4. What kind of organic acids do you know?

Recommended reading

Kellems, R.O. and Church, C.D. 2010. Livestock feeds and feeding. Prentice Hall, USA.



3.2. 3.3.2. Crude fiberBased on their composition the feeds can be divided into two main groups. Matters, which contain nitrogen, are called crude protein, and the matters without nitrogen can be divided into the group of fat or carbohydrates. Carbohydrates, depending on we are talking about them from the view of plants or from the animals, have numerous functions. We can state that for plants they are the most important nutrient group, since carbohydrates are the most of the plants from which they are built up (50-80% of the dry matter content of the plant is carbohydrate). In animal organisms they can be found in much smaller quantities, only 0.5-1%, but they are particularly important in animal nutrition, mainly due to the reason that they provide energy for different animal species in large quantities cheap. Based on their solubility the carbohydrates can be divided into three groups:

Easily soluble carbohydrates: also known as sugars. Their primary role is in taking part of the plant’s energy transformation, and the conformation of the plant tissue (Teulat et al., 2001).

Medium soluble carbohydrates: their role in the plants is the formation and the storage of backup nutrients. This group is very important both in animal and human nutrition, because here belongs the starch, the most important energy source.

Hardly soluble carbohydrates: The main function of this group is the construction and consolidation the structure of the plant. For the growing and surviving of the plant the structural strength is determining.

Crude fibre itself is the sum of the different chemical substances which construct the mechanical elementary tissues (sclerenchyma and collenchyma) of the plant. The feature of the crude fibre that they only occur in plants and it cannot be found in animal bodies. The fibre is the characteristic of plants. Each plant cell is surrounded by a shell which ensures its rigidness. This shell is formed by a complex network of polymer molecules. The different fibre constituents build on each other thus strengthening the structure of the cell. As time progress and the plant ages the amount of crude fibre increases in the plant. The woodiness of the cell wall closes the nutrient content of cell and thereby it reduces the feed conversion. Their characteristic is that they are very difficult to hydrolyse, and higher animal forms are not able to digest them since they do not have the appropriate set of enzymes to break down the fibre constituents. In spite of that they can be used as energy source for farm animals since the microbes in the digesting tract have those enzymes which are able to decompose the different kind of carbohydrate-based fibre components.

The efficiency of the utilization depends on the number of the microbes. Basically the bacteria occur in two part of the digestive system, in the forestomach and large intestine (Savage, 1977). The more microbes live in the digestive tract the more efficient is the decomposition of fibre and the amount of energy extracted from it. If we are talking about crude fibre as a nutrient this contains not just the soluble carbohydrates. In the crude fibre fraction there are non-carbohydrate based substances, even though for the most part is made up by carbohydrates. In order to get a clear picture of the carbohydrate constituents’ utilisation, let’s look at what kinds




of matters belong to this fraction.

Carbohydrate-based fiber constituents

Most of the fibres belong to this group. Their common feature is that the enzymes for their decomposition the higher forms of animals cannot produce, so their digestion happens exclusively via bacteria. The bacteria with their enzyme set decompose the polysaccharides until monosaccharide level, and they themselves consume a part of it (they utilise the 60-75% of the fibre), while the rest of it is directly available for the animals as an energy source.

Cellulose

In the world cellulose is the organic matter produced in the highest volume. The importance of the cellulose indicates its amount that the half of the fixed CO2 is cellulose. Up to more than 10,000 pieces of 1-4β glucose molecules build it up. 50 pieces of cellulose units form so called micelles which specific characteristic is the crystalline structure (Picture 2).

4.10. ábra - Picture 2. The structure of the cellulose

This structure makes the structure of the cellulose very strong and resistant, which have high importance for the plant (Kolpak and Blackwell, 1976). The cellulose is degraded by the cellulase enzyme, which is produced by unicellular organisms, bacteria, fungi and even some snails, but higher forms of animals cannot produce it (Klemm et al., 2004). As a result of the cellulase enzyme cellulose decomposes for cellobiose units, which is a disaccharide. Cellobiose is always a carbohydrate which cannot be used by animals, but the organisms, which produce cellulase enzyme, they produce cellobiase also, and through them the disaccharide falls apart into two glucose molecules, which can be utilised by higher animal forms. It can be seen that the cellulose transformation to glucose is a two-step process, which happens relatively slow. This is especially important for the ruminants, because the decomposing process mainly take place in the rumen. Due to the transformation the absorption of the glucose is continuous and this allows the stable pH of the rumen, which is essential for the normal function of the bacteria.

Though the cellulose only can be found in plants, in the animals’ world also can be found materials with a very similar construction. For example chitin, which ensures the solidity of the insects but also have similar structure the heparin, with the function of anti-gout, and even the hyaluronic acid, which can be found in humor aquosus and in the joints.

Hemicellulose

Hemicellulose is similar to cellulose in that this polysaccharide also cannot be break down by higher forms of animals. Unlike the cellulose the structure of the hemicelluloses not only glucose molecules take part but several other five and six carbon monosaccharide as well. The importance of the molecules with five carbon atoms are shown by that former this group was called pentosans, referring to the large amount of pentose molecules (xylose, ribose and arabinose). More than 250 types of polysaccharide belong to the hemicelluloses group, which forms a transition between structural and back-up nutrients (Henry, 1987). The hemicelluloses have a less stable structure than the cellulose, so the decomposing is faster. Proportionately larger quantities it can be found




in young plants and with time its role become less important and cellulose takes its place as the substance responsible for becoming woody.

Xylan

Xylan is a cell wall component, which can be found in the second largest amount (the largest is cellulose). In straws and in some hardwoods its amount can reach 25% of the organic matter content (Timell, 1967). In terms of structure the xylan is a linear polysaccharide which bases is provided by hemicellulose.

Pectin

Unlike the other three carbohydrate-based fibers forming constituents the primary role of the pectin is not to increase the solidity of the plant. (Some places it doesn't belong to the fiber content). Even the word ‘pectin’ means ‘gel forming’. The most important function is to fill the space between the cells in the tissue thus helping the water supply of the plant (Jarvis, 1984). The pectins are essentially colloidal in nature and they are able to absorb and store large amounts of water. Primary they are produced in young plants and fruits and they are attached to the cellulose. As time progresses the pectin molecules separate from the cell wall components, which means in the everyday life the ripen of the fruit. The pectins play an important role in the technologies of food industry, as with the pectins jams, marmalades jellies can be made.

Incrustrating materials

The incrustrating materials are in the group of crude fibres, even though they themselves are not carbohydrates. The word ‘crusta’ means crust, and their primary task is the solidifying and the mechanical protection. These are the matters of the forage plants which are the most resistant against chemical and enzymatic effects. At the end of the ripening and during the woodying of the plants they deposit in the cell walls, which makes the plant more solid, but the digestibility reduces, and the feeding value of the crop deteriorating. The most important incrustrating substance is the lignin.

Lignin

The lignin is a propane-phenol derivative thus it is not a carbohydrate, but it belongs to the group of crude fibres. The reason is that the lignin strongly binds with covalent bond to the cellulose and as time progresses more can be found from it (Figure 14).

While in young plants the lignin content is 2-3%, in older age this goes up to even 15% (in woods 20-40%) (Maximova et al.,2001). The lignin serves the secondary transformation of the cell wall (woodiness), which is essential for the plant, but it is considered as harmful in animal feeding. The digestibility differs from the carbohydrate based fibres, because as long as the hemicelluloses and the cellulose can be digested by bacteria and through them the animal gets energy, while the lignin is indigestible even for bacteria. As previously we could saw the lignin amount increases as time goes by, which is negative from the feeding point of view and we have to face with another problem. The incorporation of the lignin to the cellulose happens the way that it is detached to one or two glucose molecules and since this bond cannot be broken by bacteria the glucose molecules, which are connected to lignin, are lost from the point of view of feeding thereby reducing the energy content of the fibre.

4.11. ábra - Figure 14. Lignin molecule in the cellulose

Cutin




Cutin is a part of the plant’s epidermis, and it has several roles (First of all, the physical protection of the plant, secondly the reduction of water loss during transpiration). It can be only found in higher form plants. Mainly it is a mixture of hydroxylated polyesters of palmiatic acids and oleic acids, so it belongs to the group of lipids.

Suberin

It is also a kind of lipid and only higher order plants contain it and can be found right under the epidermis. It is a very good insulating material (water and air tight) and it makes the cell wall more flexible. Generally it is common that it can be found in small quantities in plants, which are used for feeding in large amounts.

Silica

The silica is an inorganic material, so the animal cannot use it as a nutrient. The typical occurrence is in aquatic plants, so it rarely cause a problem since these plants (rice, sledges, reed) we do not use in large quantities. The silica reduces the chewability and the digestibility of the plant.

Determinations the amount of crude fibre

For a long time there was only one method to determine the crude fibre content, the Henneberg-Sthomann fibre determining method (1859) but as time progressed new methods were developed because the previous one was inaccurate. During the Henneberg-Sthomann method the feed was boiled in 1,25% sulphuric acid for 30 minutes, and after filtration and washing it was boiled again in 1,25% caustic potash for 30 minutes. After another filtration the sample was rinsed several times with degreasing agent and it was incinerated. The quantity was called crude fibre, which could not be brought to a solution. The method has several disadvantages. One of the biggest problems is that with the use of solvents a part of the different crude fibre fractions also dissolve thus we get a lesser value than the real, which can be misleading in the practice. Another great problem is that we only know the amount of the fibre but we do not know the composition of it. With this method we cannot separate the main components but it would be very important to know how much cellulose, hemicellulose or even lignin is in the feed since these matters can be digest different ways (or even not at all).

The solution to the problem was that another method was developed to determine the fibre. The van Soest method (1963-roughage, 1967-seeds) tries to eliminate the mistakes of the Hennenberg-Sthomann method. The purpose of the method is to determine the cellulose and hemicelluloses content and that how much organic incrustrating material reduces the digestibility. First the feed is boiled in neutral buffered medium then it is washed with water and acetone. Thus the soluble cell content can be severed from the cell wall materials (cellulose, hemicelluloses, incrustrating materials). This is the so called neutral detergent fibre (NDF). In the second step the residual material is boiled in dilute 0.5M sulphuric acid, and with the hemicellulose becomes solution. We call this acid detergent fibre (ADF). In the third step the residue is boiled in strong (72%) sulphuric acid in which the cellulose also dissolves and only remains the acid detergent lignin (ADL). With this method the fibre components can be determined more accurately, and the amount of the digestible and indigestible substances can be measured as well (vanSoest et al, 1991). (For nore datails check Chapter 1).

The animal nutrition basically uses these two kinds of methods, but as the role of the fibres grows more recognition in human nutrition, more accurate determining methods were developed For example the enzymatic gravimetric method (Lee et al., 1992.) or the enzymatic chemical method fibre determining method (Theander et al., 1993), which allows an even more accurate measurement.

The role of the crude fibre in animal nutrition

Fundamentally the crude fibre is different from the other nutrient groups. This is due to that the organic matter content of it cannot be digested by animals on their own because they do not produce such enzymes that are able to digest it. Their decomposition and utilization are only happen via bacteria, which are living in symbiosis with animals. This result in that they play a much smaller role in animals’ nutrient supply compared to protein, fat and nitrogen free extracts. The efficiency of fibre digestion depends on the number of the bacteria. Those animals which live with a large amount of bacteria (ruminants, horses) digest the fibre more efficiently than other groups (cattle 60-70%, horse 50-55%, rabbit 20-25%, swine 15-20%). Every animal is able to digest fibre in a certain level, because every animal has bacteria in the large intestine. In case of certain animal groups (ruminants) appropriate environment for the bacteria can be found not only in the large intestine but also in the forestomach, thus these animals utilise fibre the most efficiently. Despite of the less nurturing effect the amount of the fibre is important for the animals because it effects on the function of the digestive apparatus.




Consequently every farm animal needs some fibre in the feed (Table 11).

4.3. táblázat - Table 11. Crude fibre need of different kind of animals

Crude fiber portion of dry matter content (%)

Dairy Cow 17-18

Calf 13-15

Beef 10-12

Sheep 17-18

Horse 12-16

Piglet 3

Pig 5

Breeding sow 7-8

Chicken 3

Hen 4-6

Rabbit 12-14

The table shows that the crude fibre need depends not only on the animal species but also on the age group and on the type of production. The biggest difference can be discovered for ruminants since ruminants (cattle, sheep) due to their forestomach utilise more efficiently the fibre than the other animal groups (except for horses).

The role of the crude fibre in ruminants feeding

For ruminants the crude fibre is the nutrient group which is consumed in the largest amount, which is due to that they take in very large amount of roughage. It is important that the consumed fibre should have structure (at least 75% of the total fibre amount) since the fibre with structure generate saliva production which is essential for maintaining the pH of the rumen (6,4-7,8) (Robbins et al., 1995). The generated saliva is slightly alkaline thus it is able to compensate the acidifying effect of the organic acids produced by the bacteria in the forestomach. While the organic acid production of the cattle is 6-7kg daily it needs to produce 120-160l saliva to maintain the pH of the forestomach in balance. The fibre not only keeps the pH in balance but also the dynamics of the rumen. Thanks to the fibre the rumen contracts twice per minute, which cause the feed to mix, and the generated gases are also removed. It is also very important that roughage consumed in large amount fills the rumen and provides the feeling of satiety in the animals. The fibre content on the feed effects on the rate of passing through on the digestive apparatus. The higher fibre content increases the feed’s rate of staying in the rumen, while it accelerates the emptying of the gut content. For dairy cows the higher crude fibre content of feed results in a higher fat content the milk (Van Soest, 1994).

The role of crude fibre in monogastric animal feeding

In contrast with the ruminants the monogastric animals the crude fibre as an energy source only in case of horses has importance. In practical feeding we only give crude fibre for the proper functioning of the digestive system or in case of swine breeding before slaughter to avoid fattening. The crude fibre in the feed portion has a negative effect on the other nutrients’ digestibility since fibre inhibits the digestive enzymes to access the cytoplasm. This is the so called cell wall effect (Table 12).




4.4. táblázat - Table 12. The reduction of digestibility by 1% increase of the crude fibre content

Catle 0,88%

Horse 1,26%

Rabbit 1,45%

Swine 1,68%

Hen 2,33%

The characteristics of feeding crude fibre

The feeding of crude fibre has advantages and disadvantages as well. Advantage can be that feeds with higher fibre content stay for a longer time in the digestive apparatus (mainly in the stomach and the forestomach) which results in filling and filler effect. They stimulate the wall of the stomach and the intestines (better peristalsis) which results in stronger and more frequent contractions. This has a beneficial effect on the digestion and the intestinal function. They provide sufficient consistency for the gastric and the intestinal contents (digestive fluids penetrate the feed more easily) and in case of ruminants the fibre with structure promotes salivation which is essential for the establishment of the proper pH in the rumen.

We also have to reckon with disadvantages. The presence of crude fibre decreases the nutrients usability. This feature can be traced back to several factors:

• Due to the previously mentioned cell wall effect the availability to the cell contents for the enzymes decreases which reduces the digestibility.

• The accelerating speed of passage of the intestinal contents results that less time is available for the nutrients to absorb, thus the amount of absorbed nutrients reduces.

• The protein loss of the animal increases because of the large amount fibre, which pass through the gastrointestinal tract, behaves like sandpaper and abrades off the microvilli from the intestinal wall and for their replacement extra protein is needed.

• Also reduces the digestibility of the fat content of the feed. The presence of fibre increases the number of bacteria, and since the intestinal flora disassembles the bile acid, produced by the bile, so it effects on the digestibility of the fat. Also reduces the fat digestion that a larger amount of bacteria produce a larger quantity of organic acid (acetic acid) which reduces the pH of the intestinal tract. The lower pH also has a negative effect on the bile acid production.

Feed classification based on fibre content

By their fibre content feeds can be divided into four groups.

Fibre-rich feeds: basically roughages belong here and hereby we also mention the straws too which have the highest fibre content

• straws (34-45%): (straw is not a feed but litter material)

• hays (22-35%)

• green forage (20-30%)

Medium fibre-content feeds: It can be seen that the feeds, which belong to this group, a much greater variation in the fibre content can be observed than in the case of other roughages (the difference can be up to six times)

Seeds (2-12%): we know several kinds on seeds used in practical feeding the nutrient content of these are very




different. In cereal grains wheat and corn have the lowest fibre content (2-3%), while oat has the highest fibre content, which can reach 12%. The barley also has relatively high fibre content (7-8%). These values must be considered during feeding and compile the appropriate feed portions based on them

Poor fibre content feeds

• root and tuber fodders (approx. 1%): They even contain less fibre than the seeds barely 1% of the dry matter content. In practice we use the industrial (sugar industry) some kind of by-product of this group of plants (wet or dry beet pulp).

Feed containing no fibre: since fibre is only characteristic of the plants, every feed which is animal origin contains no fibre.

Crude fibre concentrates

Nowadays we use in broiler and swine feeding crude fibre far more for the physical characteristics than for the potential nutritional value. In the past crude fibre was provided by untreated by-products (wheat bran, rice bran, soy hull) which could have contained undesirable matters. This did not cause any problem until growth promoter antibiotics were allowed to use, but today the use of these materials are prohibited. It was time figuring out for a new fibre source which is not dangerous for the animals. This could be the crude fibre concentrate, which is extracted cellulose and lignin based and the fibre content is at least 60%. The concentrate has several advantages compared to the conventional fibre types:

• up to two times more fibre content than the any other naturally occurring matter. Due to the higher concentration less is needed to achieve the adequate fibre content so the amount of the other nutrients can be increased in the feed, which results in a more concentrated feed.

• Micotoxin free: In contrast with the various by products the crude fibre concentrate is free from micotoxins due to different treatments, so it is healthier for the animal.

• Soluble fibre free: Due to the fact that it does not contain soluble fibres we can use a more accurate nutrient value, which is more favourable for the animal and has economic advances as well.

• Stimulates the villi: the concentrated insoluble fibrils stimulate the growth of the microvilli and the enzymatic activity, which improves the efficiency of digestion.

• High swellable and water-absorbing capacity: the lignocellulose based crude fibre concentrate’s water absorbing capacity is very high (68g water per g of concentrate). This is roughly 2-3 times higher value than the sugar beet pulp’s. Due to the large and very quick (less than 1 minute) swelling capacity even a very small portion has a significant effect on the feed intake. Therefore the satiety is reached very quickly thus the amount of the intake of the feed can be controlled.

Test questions:

1. What is the role of the lignin?

2. How the crude fiber can be digested?

3. What are the advantages of the fiber concentrates in the nutrition?

4. What do you know about the cellulose?

5. Describe the roles of the crude fibre in ruminants feeding!

Recommended reading



Moughan, P.J., Verstegen, M.W.A., Visser-Reyneveld, M.I. (Eds). 2000. Feed evaluation: principles and practice




Wageningen Pers, Wageningen, NL.

4. 3.4. VITAMINS AND THEIR INTERACTIONS4.1. 3.4.1. Vitamins in generalVitamins are required in minor amounts for the normal functioning of the animal body, for maintenance, growth, health and production (NRC, 2012). They are not feedstuffs in the ordinary sense, but have a catalytic function. Many plants and microorganisms are capable of synthesizing vitamins, a feature not shared by animals, whose capacity for biosynthesis is, in general, limited. Vitamins must be provided from exogenous sources, chiefly in the diet or from biosynthesis by microorganisms present in the gastrointestinal tract. The definition that vitamins are organic compounds which must be supplied to animals in small amounts from external sources is not completely satisfactory, since in some instances the vitamins required are synthesized within the body tissues. The term ’vitamins’, derived from ’vital amines’, was introduced by Funk to describe these accessory food factors, which he thought contained amino nitrogen. It is now known that only a few contain amino nitrogen and the name has been shortened to vitamins, a term which has generally been accepted as a group name.

Vitamins are divided into two groups: fat-soluble (including vitamins A, D, E and K) and water-soluble (the members of the B-complex and vitamin C). The various vitamins differ greatly in chemical structure and metabolic function. Table 13 gives the presently accepted designations for the vitamins.

In addition to the 13 biologically active current members of the vitamin class, many other substances have in the past been designated as vitamins. Some are now regarded as not physiologically active; others, while accepted as active, are no longer termed vitamins. As a group, vitamins are recognised by two characteristic properties. Firstly, daily requirement for vitamins is very small, usually measured in microgrammes or milligrammes. Secondly, vitamins are organic compounds, differing in this respect from trace elements such as iron, iodine, manganese and zinc, which are also essential compounds.

4.12. ábra - Table 13. Vitamins playing a significant role in animal nutrition

13 vitamins have been identified to date, each of these representing a group of related compounds with the same qualitative activity. In addition, other substances (e.g. carnitine (vitamin B 11), orotic acid (vitamin B13), xanthopterin (vitamin B14), pangamic acid (vitamin B15), inositol or Bios I, lipoic acid or thioctic acid, rutine




(vitamin P), and ubiquinone (coenzyme Q)) have been classed alongside the vitamins, although their vitamin character has not yet been established (Table 14).

4.13. ábra - Table 14. Designation of ‘obsolete vitamins’ according to their alphabetical terminology and trivial (generic) names

Requirements

The term ‘requirement’ is not used in a uniform way. It covers requirements from minimum to optimum. The marginal zone represents vitamin levels lower than minimum requirements which may predispose animals to deficiency. The requirement zones are the minimum quantities required to prevent deficiency signs, but may lead to sub-optimum performance, although livestock may appear normal.

The optimum allowances permit animals to achieve their full genetic potential for optimum performance. In the excess zone, vitamin levels vary from concentrations which are still safe, but uneconomical, to those which may produce toxic effects. Requirements are expressed in mg or international units (IU) per kilo live weight or per animal, or on the basis of the amount of feed (mg per kg diet).

The vitamin requirements of livestock under various conditions have been the subject of numerous studies; this mass of research has led to approximate estimates of vitamin requirement for the various animal species. In addition to external factors, which affect the utilisation of the vitamins supplied, other factors play a role. Under conditions of physical stress or increased production vitamin requirements can rise considerably. Analytical determination of the vitamin content of feedstuffs is costly and time-consuming. Some vitamins can only be assayed by (micro-)biological methods, subject to systematic errors. Further problems in calculating vitamin supply are the degree of the utilisation of vitamins from different feedstuffs, and the biological variations (appreciable in certain cases due to the impariment by various factors of the utilisation of vitamins administered) and experimental error present in empirical data on minimum vitamin requirements. Vitamin supplements should therefore be added to the diet to ensure that requirements are met. In contrast to other active substances, such as hormones, large quantities of vitamins, particularly the water-soluble vitamins, can be absorbed without adverse effects. Only when the supply exceeds an upper level for a prolonged period can symptoms of so-termed hypervitaminosis develop.

4.2. 3.4.2. Fat-soluble vitaminsVitamin A

Chemical structure and properties

Vitamin A is an almost colourless, fat-soluble, long-chain, unsaturated alcohol with five double bonds. It is made up of isoprene units with alternate double bonds, starting with one in the ß-ionone ring that is in




conjugation with those in the side chain. Vitamin A is a generic term applying to all derivatives of ß-ionone (except carotenoids) which possess the biological activity of all-trans retinol or are structurally closely related to it. The substances in the vitamin A group are called all-trans. Retinol is the alcohol form of vitamin A.

Some naturally occurring carotenoids act as precursors of vitamins. The conversion of carotenoids to vitamin A occurs in the intestines. Carotenoids occur as orange-yellow pigments, mainly in green leaves and, to a lesser extent, in maize.

Four of them, α-carotene, ß-carotene, τ-carotene and cryptoxanthine (the main carotenoid of maize), are of particular importance due to their provitamin A activity. The vitamin A activity of ß-carotene is substantially higher than that of other carotenoids. Both carotene and vitamin A are destroyed by oxidation, and this is the most common cause of any depreciation in the potency of sources.

Metabolism and functions

Vitamin A is important in the normal functioning of epithelia1 tissues, normal vision and the development of bones. This vitamin is necessary to support growth, health and life in higher animals and is therefore important as a dietary supplement for all animals, including ruminants. Vitamin A is necessary for cell replication.

After ingestion of vitamin A, the action of various enzymes and bile salts produces a retinol-containing micelle, and retinol is readily absorbed into mucosal cells, mainly in the upper half of the intestine. Following adsorption in mucosal cells, vitamin A is transported by the lymph into the blood stream and is stored mainly in the liver in the form of esters. When liver reserves are mobilised, the ester forms are transported in the blood in the alcohol form bound to a protein. The level of vitamin A alcohol in the blood is usually constant. Therefore, variation of vitamin A esters in the blood is the only good measure of the rate of absorption and deposition.

Occurrence

Vitamin A itself does not occur in plants, but its precursors (carotenoids) do, and can be converted to true vitamin A by a specific enzyme located in the intestinal walls of animals. The vitamin occurs in animal tissues, and therefore protein meals of animal origin serve as a source of vitamin A in poultry and swine feeds. Milk fat, egg yolk arid liver are rated as rich sources, but not if the animal from which they originate received a vitamin A-deficient diet for an extended period. Since the vitamin is present in the fat, skimmed milk has very low vitamin A content.

Sources of supplemental vitamin A are derived primarily from fish liver oils, in which the vitamin occurs largely in esterified form, and from industrial chemical synthesis.

Requirernents

In general practice, requirements are normally expressed per unit of diet rather than per kilogramme body weight. To establish a satisfactory vitamin A level for practical diets it is necessary to consider factors that may alter the vitamin A requirement. Type and level of production are important, as higher production rates increase requirements, as do pregnancy, lactation and egg production. It is likely that any condition that results in increased cellular proliferation of any tissue will increase vitamin A requirements. A common belief exists that physiological factors, such as stress, disease and high production, increase vitamin A requirements. Other factors that may affect metabolism and increase requirements for vitamin A include free nitrates in feeds and inadequate dietary protein, zinc or phosphorus.

Despite an efficient mechanism of vitamin A transfer across the placenta of mammals, including that of ruminants, serum vitamin A concentrations in foetuses are uniformly lower than in their dams. Colostrum has a high vitamin A concentration, and colostrum production is probably partially responsible for the severely reduced concentration of serum retinol in cows near parturition. Colostral vitamin A seems to be dependent on the dam’s hepatic reserves.

Vitamin A requirement in ruminants varies from 2200 to 3900 IU per kg dry ration for beef cattle and from 3200 to 4000 IU per kg diet for dairy cattle (NRC 1984 and NRC 1989 respectively).

Other vitamin A requirements listed in NRC (1994) are: 1500 IU per kg diet for broilers, growing geese and growing layer replacement birds; 4000 IU per kg diet for laying and breeding chickens and breeding geese; 4000 IU per kg diet for all classes of turkeys and ducks.




The vitamin A requirement of growing to finishing pigs is listed as being from 1300 to 2200 IU per kg diet. Breeding animals require 4000 IU per kg, gilts and lactating sows 2000 IU per kg diet. Lactating animals require less vitamin A per unit of feed than for breeding due to levels of allowed feed consumption (NRC, 2012).

Vitamin D


The term ‘vitamin D’ refers to a group of closely related compounds that possess antirachitic activity. These may be supplied in the diet or by irradiation of the body. Approximately 10 provitamins are known, which, after irradiation, form compounds possessing variable antirachitic activity. The two most prominent members of this group are ergocalciferol (vitamind D2) and cholecalciferol (vitamin D3). Vitamin D occurs in the form of colourless crystals, insoluble in water but readily soluble in alcohol and other organic solvents. It is less soluble in vegetable oils, and can be destroyed by overtreatment with ultraviolet light.


Absorption of phosphorus as such is independent of vitamin D intake, and inefficient absorption in rickets results from failure to absorb calcium, while improvement in the administration of vitamin D results from improved calcium absorption. Another important function is the biosynthesis and maturation process of collagen in preparation for mineralisation.

Because vitamin D is fat-soluble, it requires the action of bile salts for absorption, which occurs chiefly in the duodenum and the colon.

A primary function of vitamin D is in calcium transport, including the intestinal absorption of calcium and the mobilisation of calcium and phosphorus from intestines and bones. An adequate supply of vitamin D stimulates the absorption of calcium and phosphorus from the intestines and increases significantly the reabsorption of calcium and phosphorus in the renal tubules.

Occurrence

In the natural environment distribution of vitamin D is very limited, but D-provitamins occur extensively. Of feeds for livestock, grains, roots, and oilseeds, together with their numerous by-products, contain insignificant amounts of vitamin D. Ergocalciferol is derived from a common plant steroid, ergosterol, and is the usual dietary source of vitamin D. Cholecalciferol is produced exclusively from animal products.

Requirements

When sufficient sunlight is available, animals do not have a nutritional requirement for vitamin D, since vitamin D3 is produced in the skin by the action of UV-light on 7-dehydrocholesterol. Other factors influencing dietary vitamin D requirements include the amount, ratio and availability of dietary calcium and phosphorus, species, and physiological factors. The diet of rapidly growing young animals should contain between 0.6 and 1.2% calcium in the dry matter, with a calcium/phosphorus ratio in the range of 1.2:1 to 1.5:1. For adult animals at maintenance, lower calcium levels and wider calcium/phosphorus ratios are possible. In these situations vitamin D requirements are at a minimum and the risk of vitamin D deficiency is lower. Intestinal pH, in addition to other dietary nutrients, influences calcium and phosphorus requirements, and thus vitamin D requirement.

The currently recommended dietary vitamin D allowances for dairy cows are based on limited data. The NRC (1989) has recommended daily intakes of 30 IU vitamin D per kg live weight for adult dairy cows, which amounts to between 15,000 and 20,000 IU per cow per day. Dairy cows, like other animals, do not appear to require a dietary source of vitamin D if they are exposed to natural sunlight or some other source of high energy UV light. Animals housed indoors, or even those outside in winter light, may require dietary supplementation.

The ARC (1980) estimate of requirement of 10 IU per kg live weight per day for dairy cows has been recommended largely to increase milk vitamin D content. Since recent indications suggest that pregnant sheep (and therefore, presumably, cows) have a higher requirement than non-pregnant animals, an allowance of 10 IU per kg live weight per day has also been recommended in this case.

The vitamin D3 requirements listed in NRC (1994) are 200 International Chick Units (ICU) per kg diet for broilers and Leghorn classes from 0 to 20 weeks, and 220 ICU per kg diet for ducks. However, ICU and




International Units (IU) are considered equal for vitamin D3, but not equal for vitamin D2. Higher levels of vitamin D3 (ICU per kg; IU per 1b) are required for laying and breeding Leghorns, and also for turkeys and Japanese quail.

It has generally been assumed that for all but a few species, vitamin D2 and vitamin D3 are equally potent. However, vitamin D3 may be 30 to 40 times more effective than the D2 form for poultry.

Swine do not have a nutritional requirement for vitamin D when sufficient sunlight is available, since vitamin D3 is produced in the skin through the action of UV irradiation on 7-dehydrocholesterol. The vitamin D3 requirements of swine listed in NRC (2012) range from 150 to 220 IU per kg of diet, for breeding and lactating animals 800 IU per kg diet.

Vitamin E


Vitamin E comprises two groups, tocopherols and tocotrienols, which are all produced in green plants. The term ‘vitamin E’ refers to mixtures of physiologically active tocopherols; four tocopherols (α, β, τ, δ) and four tocotrienols (α, β, τ, δ) are found in the natural environment. The difference between tocopherols and tocotrienols is unsaturation of the side-chain in the tocotrienols. Only the tocopherols are of major physiological importance.

α-tocopherol is a yellow oil, insoluble in water but soluble in organic solvents. Tocopherols are extremely resistant to heat but readily oxidised. Natural vitamin E is easily destroyed by oxidation, which is accelerated by heat moisture, rancid fat, and certain trace minerals. α-tocopherol is an excellent natural antioxidant that protects carotene and other oxidisable materials in feed and in the body. The dl α-tocopheryl acetate (also called all-rac-α-tocopheryl acetate) is accepted as the International Standard (1 mg = 1 IU). Synthetic free tocopherol, dl-α-tocopherol, has a potency of 1.1 IU per mg. Naturally occurring α-tocopherol and d-α-tocopherol (also called RRR-tocopherol) show activity of 1.49 IU per mg; its acetate, 1.36 IU per mg.

The stability of all naturally occurring tocopherols is poor, and substantial losses of vitamin E activity occur in feeds when processed and stored under oxidation-promoting conditions, for example heat, oxygen, moisture, oxidising fats and trace minerals.


The absorption of vitamin E is related to fat digestion and facilitated by bile and pancreatic lipase. Whether presented as free alcohol or as esters, most vitamin E is absorbed as the alcohol. Esters are hydrolysed in the gut wall, and the free alcohol enters the intestinal lacteals and is transported via lymph to the general circulation. Vitamin E recovery in faeces has been found to range from 65% to 80% in humans and rabbits, but not in chicks or pigs. It is not known how much faecal vitamin E represents unabsorbed tocopherol and how much may be excreted in the bile.

Vitamin E is involved in a number of physiological functions: acting as a biological antioxidant; promoting intracellular respiration; activating nucleic acid metabolism; stimulating endocrine secretions (important for fertility and gestation); potentiating the immune system; and, finally, acting as a detoxifying agent.

A substantial amount of research has been published on the immunomodulatory role of vitamin E in pigs (Babinszky, 1994; Gaskins and Kelley, 1996) and in laboratory animals. Vitamin E protects cellular and membrane lipids from peroxidation catalysed by free radicals. When vitamin E or selenium is added to nutritionally adequate diets there is generally an increase in the ability of pigs to synthesise antibodies. Newborn pigs have very low levels of plasma tocopherols, the concentration of these being increased considerably after consumption of colostrum. Therefore, colostral-derived vitamin E may be important in the normal development of antibody synthesis in young pigs.

Several studies have demonstrated that vitamin E and selenium enhance T-cell proliferation in pigs. Vitamin E supplementation of the sow’s diet influences vitamin E concentrations in the serum of the piglets during the first part of lactation (Babinszky et al., 1991). Moreover, antibody titres against the experimental immunogen ovalbumin have been shown to be increased one week after immunisation in pigs weaned from sows fed the




highest dose of vitamin E (Babinszky et al., 1991). Studies designed to assess how dietary vitamin E and selenium affect immune parameters in gestating and peripartum sows have revealed that vitamin E restriction depresses peripheral blood lymphocyte and neutrophil functions, whereas selenium restriction predominantly depresses the phagocytic functions of neutrophils.

Occurrence

The most active form of natural vitamin E found in feed ingredients is d-α-tocopherol. Vitamin E is widespread in the natural environment, the richest sources being vegetable oils, cereal products containing such oils, eggs, liver, legumes and green plants in general. Animal by-products supply only small amounts, and milk and other dairy products are poor sources. Wheat germ oil is the most concentrated natural source, and various other oils such as soybean, peanut, and particularly cottonseed oil are also rich in vitamin E.

The principal commercially available forms of vitamin E used in the food and feed are acetate and hydrogen succinate esters of RRR α-tocopherol and the acetate ester of all-rac-α-tocopherol. During commercial synthesis dl-α-tocopherol is esterified to the more stable acetate, the ester being extremely resistant to oxidation.

Thus, dl-α-tocopherol acetate does not act as an antioxidant in the feed and exhibits antioxidant activity only after being hydrolysed in the intestine, free dl-α-tocopherol thereby being released and absorbed.

Requirements

Vitamin E requirements are very difficult to determine due to their interrelationships with other dietary factors. Requirement for vitamin E increases with increasing levels of polyunsaturated fatty acids (PUFA), oxidising agents, vitamin A, carotenoids and trace minerals, and decreases with increasing levels of fat-soluble antioxidants, sulphur amino acids and selenium. In otherwise adequate diets containing sufficient cystine and methionine and containing a minimum of PUFA, vitamin E requirements appear to be low.

Requirements for vitamin E and selenium are dependent on the dietary concentrations of each other. Vitamin E reduces selenium requirement by maintaining body selenium in an active form, or preventing loss from the body, and by preventing the destruction of membrane lipids.

The lipid composition of the diet, especially the PUFA content, has a dramatic influence on vitamin E requirement. Therefore, it is recommended that vitamin E requirements be expressed as a function of PUFA intake. In ruminants, PUFA are extensively hydrogenated, or saturated, before absorption; thus, it might appear that ruminant vitamin E requirements should be low. Cations (e.g. iron and copper) catalyse the production of free radicals, and may be considered pro-oxidant nutrients. High intakes of iron (1200 ppm dry diet) may increase the vitamin E requirement of dairy cows (Mueller et al., 1989).

Vitamin requirement is given as 15 IU per kg diet for ruminants (NRC 1989), and in poultry species varies from 5 to 25 IU per kg diet (NRC 1994). Growing and laying chickens have the lowest requirement at 5 IU per kg diet.

The NRC (2012) requirement for growing pigs varies from 11 to 16 IU per kg diet. Only limited information is available on vitamin E requirement for reproduction. The NRC (2012) recommends 44 IU per kg diet for breeding and lactating swine.

Vitamin K


Vitamin K is a generic term for a homologous group of fat-soluble vitamins consisting of 2- methyl-1,4-naphthoquinone derivatives, commonly called menadione. This vitamin extracted from plant material is termed phylloquinone, or vitamin K1. Vitamin K-active compounds derived from material after bacterial fermentation are termed menaquinones, or vitamin K2. The simplest form of vitamin K is synthetic menadione (K3). Vitamin K is a golden yellow, viscous oil; natural sources are fat-soluble, heat-stable, but labile to oxidation, alkali, strong acids, light and irradiation. In contrast to natural sources of vitamin K, some of the synthetic products, such as salts of menadione, are water-soluble.





The main physiological functions of vitamin K are as a blood clotting factor, in protein synthesis, and in cellular metabolism. Vitamin K deficiency may result from dietary deficiency, lack of microbial synthesis within the gut, inadequate intestinal absorption or inability of the liver to use the vitamin K available. The major clinical indicator of vitamin K deficiency in all animal species is impairment of the blood coagulation process. Other clinical indicators include low prothrombin levels, increased clotting time and haemorrhaging.

Like all fat-soluble vitamins, vitamin K is absorbed in association with dietary fats. Absorption, occurring passively in the small intestine and the colon, depends on the incorporation of the vitamin into mixed micelles, and optimal formation of these micellar structures requires the presence of bile and pancreatic juice. In the body vitamin K is transported via the lymphatic system and concentrated in the liver with a low retention time. Menadione is converted in the tissues to the biologically active form.

Occurrence

Vitamin K is found in fresh, dark green vegetables and in extract of pine needles. Alfalfa leaf meal has a low vitamin K content. By-product feeds of animal origin, including fish meal and fish liver oils, are good sources of vitamin K. Menaquinones (vitamin K2), produced by the bacterial flora in animals, are particularly important in meeting vitamin K requirements in mammals. In non-ruminants, synthesis is in the lower gut, an area of poor absorption, and availability to the host is limited, except in the case of coprophagy, whereby the vitamin K synthesised is highly available. Chickens, however, do not receive sufficient vitamin K from intestinal microbial synthesis, but most feedstuffs of plant origin containing high levels of vitamin K are not usually fed to poultry. Water-soluble derivatives of menadione are the principal forms of vitamin K in commercial diets.

Requirements

Rumen microbes in particular synthesise large quantities of vitamin K, a dietary source of which is therefore not required in ruminants.

Due to microbial synthesis, precise definition of vitamin K requirements is not feasible. The daily requirement for most animal species falls within a range of 2 to 200 µg vitamin K per kg body weight, dependent upon age, sex, strain, anti-vitamin K factors, disease conditions and conditions influencing lipid absorption. A rapid rate of feed passage through the digestive tract may also influence vitamin K synthesis. Swine obtain more benefit from intestinal vitamin K synthesis than poultry.

Estimated dietary vitamin K requirement is 0.50 mg per kg diet for all classes of swine (NRC, 2012). In poultry, vitamin K requirements are met by a combination of dietary intake and limited microbial biosynthesis in the gut, and the dietary requirement suggested by the NRC (1994) ranges from 0.4 to 1.0 mg per kg diet.

4.3. 3.4.3. Water-soluble vitaminsVitamin B1 (Thiamin)


Vitamin B1, also called thiamin(e) or aneurin(e). It consists of a molecule of pyrimidine ulinked by a methylene bridge to a molecule of thaizole and contains both nitrogen and sulphur atoms. Thiamin is isolated in pure form as the white thiamin hydrochloride. It has a characteristic sulphurous odour and a slightly bitter taste, and is very soluble in water, sparingly so in alcohol, and insoluble in fat solvents. The vitamin is very sensitive to alkali.


A condition for the normal absorption of thiamin is sufficient production of stomach hydrochloric acid. Phosphoric acid esters of thiamin are split in the intestine. Free thiamin is soluble in water and is easily absorbed, especially in the duodenum. Ruminants can also absorb free thiamin from the rumen, but the rumen wall is not permeable to bound thiamin or to thiamin in rumen microorganisms. The horse can absorb thiamin from the caecum. Although the vitamin is readily absorbed and transported to cells throughout the body, it is not stored to any great extent. Absorbed thiamin is excreted in both urine and faeces, with small quantities excreted in sweat. Faecal thiamin may originate from feed, synthesis by microorganisms, or endogenous synthesis (e.g., via bile). The main functions of thiamin include that as a co-factor of enzymes in the intermediate metabolism of carbohydrates, e.g. glycolysis and the citric acid cycle, and as an active substance in the nervous system.




Occurrence

Good thiamin sources are cereals, milling by-products, oil extraction residues and yeast. The thiamin content of most common feeds is higher than requirements for most species. The utilisation of available thiamin in feedstuffs may be limited and may also be impaired by thiamin antagonists; therefore, it is common practice to add supplemental thiamin to poultry and pig diets.

Requirements

Diet composition exerts a strong influence on thiamin requirement. Since it is specifically involved in carbohydrate metabolism, thiamin requirement is influenced by the level of dietary carbohydrate relative to other energy-supplying components. The need for thiamin increases with carbohydrate consumption. Thiamin deficiency leads to more rapid depletion of body reserves when animals are maintained on a feed rich in carbohydrates than when they are receiving a diet rich in fat and protein. The ‘thiamin-sparing’ effect of fats and protein has been recognised for some time. Genetic factors and metabolic status also affect thiamin requirements, which are obviously higher if feeds contain raw materials (i.e. fish) or additives with antithiamin activity. Disease can also result in increased thiamin requirement.

In most species thiamin requirements are difficult to establish, due to endogenous vitamin synthesis by intestinal microflora. Despite a high level of thiamin synthesis by rumen microbes and the fact that feeds, particularly whole grains, contain thiamin, deficiencies do develop in ruminants. Results of studies indicate that thiamin in the rumen is decreased by reduced ruminal pH, a characteristic of cattle fed high-concentrate diets. Thiamin requirements in pigs generally range from 1.0 to 1.5 mg per kg diet (NRC, 2012). In poultry, thiamin requirements generally range from 0.8 to 2.0 mg per kg diet (NRC, 1994). Requirement for thiamin is proportional to body size. Light poultry breeds (e.g., Leghorn) seem to have higher thiamin requirements than do heavy breeds. The health status of livestock can be protected by means of thiamin injections administered at an appropriate time. Thiamin supplementation should not normally be considered for grazing ruminants.

Thiamin sources available for addition to feed are the hydrochloride and mononitrate forms. Because of its lower solublility in water, the mononitrate is preferred for addition to premixes.

Vitamin B2 (Riboflavin)


Riboflavin contains a dimethylisoalloxazine nucleus combined with the alcohol of ribose as a side chain. It exists in three forms, as the free riboflavin and as the coenzyme derivatives flavin mononucleotide (FMN, riboflavin 5-phosphate) and flavin adenine dinucleotide (FAD). These coenzymes are synthesised sequentially from riboflavin. The vitamin is an odourless, bitter, orange-yellow compound which melts at about 280 °C. Riboflavin is only slightly soluble in water but easily soluble in dilute basic or strong acidic solutions. It is heat-stable in neutral and acid, but not in alkaline solutions.

Metabolism and function

Following ingestion, the bound form of riboflavin is hydrolysed in the small intestine to free riboflavin, which then enters the mucosal cells of the small intestine, through active transport which is increased by bile salts. In the portal system it is bound to plasma albumin and transported to the liver. Apart from tissue saturation, no appreciable amounts of riboflavin are stored in the body.

As a coenzyme, riboflavin acts as an intermediary in biological oxidation-reduction reactions. Flavoproteins are essential for carbohydrate and fat metabolism.

Occurrence

Riboflavin occurs in the phosphase form or bound to specific proteins to form enzymes. Good sources are milk and dairy and animal products. Riboflavin is commercially available as a crystalline compound produced by chemical synthesis or fermentation. Most commercially available riboflavin is made by bacterial synthesis.

Requirements

Riboflavin is one of the vitamins most likely to be deficient in non-ruminant farm animals and humans. Before




their rumens are developed, ruminants up to 2 months of age, if early-weaned or dependent on milk replacer, also require dietary riboflavin. Swine and poultry diets based on grain and plant protein sources are likewise often on the borderline of riboflavin deficiency. Riboflavin requirements vary with heredity, growth, environment, age, activity, health, other dietary components and synthesis by the host.

Due to the ruminal microbial synthesis of riboflavin, ruminants have no dietary requirement for it.

Swine have a riboflavin requirement of between 2 and 4 mg per kg diet (NRC, 2012). The NRC (2012) requirement declines as the pig grows, from 4 mg per kg diet for pigs of 1 to 5 kg body weight to 2 mg per kg for growing-finishing pigs weighing 50 to 100 kg.

The various types of poultry have a requirement between 1 and 4 mg per kg diet (NRC, 1994). The NRC (1994) requirement for broiler chicks is 3.6 mg per kg of diet. However, more recent information suggests that, to prevent signs of leg paralysis in broilers fed a maize-soybean diet, the minimum requirement of 4.6 mg riboflavin per kg diet is recommended.

Niacin (nicotinic acid)


Chemically, niacin is one of the simplest vitamins. Nicotinic acid and nicotinamide correspond to 3-pyridine carboxylic acid and its amide respectively.

Antivitamins, or antagonists, of niacin have the basic pyridine structure, two of the major antagonists of nicotinic acid being 3-acetyl pyridine and pyridine sulphonic acid. Nicotinic acid and nicotinamide (niacinamide) exhibit the same vitamin activity; the free acid is converted to the amide in the body.

Both nicotinic acid and nicotinamide are white, odourless, crystalline solids soluble in water and alcohol. They are very resistant to heat, air, light and alkali, and are thus stable in foods. Niacin is also stable in the presence of the usual oxidising agents.


No extensive investigation has yet been performed into niacin and nicotinamide transport. There seems to be continual transport of the two compounds via the blood stream such that there is cross-feeding of the tissues and organs for the synthesis of pyridine nucleotides. Blood transport of niacin is associated mainly with the red blood cells.

Nicotinic acid in the body is converted to a metabolically active form, nicotinamide, which forms an active part of the coenzymes nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide phosphate. These enzymes perform the basic functions in the metabolism of protein, carbohydrates and fats. They are also important in the citric acid cycle. The energy released during the process is stored in adenosine triphosphate (ATP), and can be released by means of the conversion of ATP to adenosine diphosphate (ADP).

The major physiological role of niacin is in the enzyme system for cell respiration. The vitamin is essential for pigs, poultry and other non-ruminant animals.

Niacin has been shown to have a positive effect on the efficiency of rumen microbial protein synthesis (Flachowsky, 1993).

Occurrence

Niacin is widely distributed in foods of both plant and animal origin.

Most species can use the essential amino acid tryptophan to synthesise niacin. Niacin is often present in feeds in a bound form which is not available. The niacin present in the various types of cereal grain and their by-products is in a bound, complex form which is virtually unavailable, at least to monogastric animals. It seems that much of this niacin is also unavailable to rumen microorganisms. The commercial product is a white or off-white free-flowing granular powder, sparingly soluble in water and stable in air, but affected by prolonged exposure to light and humidity.




Requirements

Factors influencing niacin requirements in swine include: genotype; ability to synthesise niacin from tryptophan; bioavailability of niacin in feeds; increased stress and subclinical diseases; a tendency towards more intensified operations (which may decrease the opportunity for coprophagy); earlier weaning (which increases the requirement for higher niacin levels in milk-substitute diets for prestarter and starter feeds); and various nutrient interrelationships, including amino acid imbalances.

A daily supplement of 3 to 6 mg niacin per dairy cow is recommended to optimise milk yield, particularly in the first lactation period. Supplementation should begin two weeks before calving and cover the first 8 to 10 weeks of lactation.

Niacin requirements in swine is 30 mg per kg of diet (NRC, 2012). Information available for the determination of niacin requirement in pregnant and lactating sows is limited. An estimated requirement of 10 mg per kg diet has been extrapolated from data relating to growing pigs (NRC, 2012). However, sows are incapable of accumulating large quantities of niacin, and require supplementary dietary niacin to prevent the development of deficiencies which might seriously limit their productivity.

Most of the niacin in dietary ingredients used for pig feed is in a bound form which is largely unavailable. Supplemental niacin should therefore be added to diets for all classes of pig. In poultry, niacin is essential for critical biochemical processes which influence maintenance, growth and reproduction.

The NRC (1994) recommends niacin supplementation of between 10 and 70 mg per kg diet for the various classes of poultry.

Vitamin B6 (pyridoxine)


The term ‘vitamin B6’ refers to a group of three compounds, pyridoxol (pyridoxine), pyridoxal and pyridoxamine, their activity being equivalent in animals but not in the various microorganisms. Vitamin B 6 acts as a component of many enzymes involved in the metabolism of proteins, fats and carbohydrates.

Forms of vitamin B6 are stable in the presence of heat, acid and alkali, but exposure to light, particularly in neutral or alkaline media, is highly destructive. The various forms of vitamin B6 are colourless crystals soluble in water and alcohol.


Digestion of vitamin B6 first involves splitting the vitamin, as it is bound to the protein portion of feeds. Vitamin B6 is absorbed mainly in the jejunum, but also in the ileum by passive diffusion. The level of absorption from the colon is insignificant, even though colon microflora synthesise the vitamin. Vitamin B 6 compounds are all absorbed from the diet in the dephosphorylated forms. After absorption, vitamin B 6 compounds rapidly appear in the liver, where they are converted mainly into phyridoxal phosphate (PLP), considered to be the most active vitamin form in metabolism.

Vitamin B6 is widely distributed in the body, being stored in small quantities as pyroxal-5- phosphate or pyridoxamine-5-phosphate. Vitamin B6 is involved in a number of metabolic functions, e.g. the metabolism of proteins, carbohydrates, fats, sulphur-containing amino acids, tryptophan and minerals; the synthesis of non-essential amino acids; and the absorption of amino acids.

Occurrence

The vitamin present in the various types of cereal grain is concentrated mainly in bran, the rest containing only small amounts. The richest source is royal jelly, produced by bees. Most vitamin B6 present in animal products is in the form of pyridoxal and pyridoxamine phosphates. In plants and seeds the usual form is pyridoxol. Pyridoxine hydrochloride, a commercial product, is a fine, off-white powder. It is stable in the presence of air and heat, but sensitive to light and humidity.

Requirements




Vitamin B6 requirement has been found to depend generally on species, age, physiological function, dietary components, intestinal flora and other factors not yet fully understood. Due to microbial synthesis, ruminants have no dietary requirement for vitamin B6. Young ruminants which do not have a fully developed rumen, however, require a dietary source. The vitamin is produced by microorganisms in the intestinal tract in swine, but there is doubt as to whether significant quantities are absorbed and utilised. In swine, vitamin B 6 requirement generally varies from 1.0 to 7.0 mg per kg diet (NRC, 2012). Vitamin B 6 requirement increases when high-protein diets are fed. According to results obtained from several studies, high dietary levels of tryptophan, methionine and other amino acids increase the requirement for vitamin B6 too.

Vitamin B6 for poultry generally vary from 3.0 to 4.5 mg per kg diet (NRC, 1994). In poultry, the quantity of dietary protein affects the requirement for vitamin B6, which increases when high protein diets are fed.

Pantothenic acid


Pantothenic acid is an amide consisting of pantoic acid ulinked to ß-alanine. The vitamin is derivatised at its carboxyl end by ß-mercaptoethylamine and at its alcohol end by phosphate to form a pseudodinucleotide containing phosphoadenylic acid. Coenzyme A contains the vitamin combined with adenosine 3’-phosphate, pyrophosphate, and ß-mercaptoethylamine. Another metabolically active form of pantothenic acid is acyl carrier protein (ACP). The free acid of the vitamin is a viscous, pale yellow oil, readily soluble in water and ethyl acetate. The oil is very hygroscopic and is easily destroyed by acids, bases and heat.


Little information is available on the digestion, absorption and transport of this vitamin. Pantothenic acid, its salt and the alcohol are absorbed from the intestinal tract, probably by diffusion. Within tissues pantothenic acid is converted to coenzyme A and other compounds in which the vitamin forms a functional group.

Feeds contain pantothenic acid in both bound and free forms. It is necessary to liberate the pantothenic acid from the bound forms in the digestive process prior to absorption.

Urinary excretion, prompt when taken in excess, is the major route of loss from the body of absorbed pantothenic acid. Animals do not appear to have the ability to store appreciable amounts of this vitamin, organs such as the liver and the kidney containing the highest concentrations. Most of the pantothenic acid in the blood exists in the form of coenzyme A in red blood cells. Blood serum contains no coenzyme A but does contain free pantothenic acid.

The most important function of coenzyme A is as a carrier mechanism for carboxylic acids.

Occurrence

Pantothenic acid occurs extensively in animal by-products, yeast cereals and some green plants. Calcium pantothenate is the pure form of the vitamin, used for commercial purposes. This crystallises from methanol in the form of white needles, and the crystallised form is reasonably stable in the presence of light and air.

Requirements

For growth and reproduction, most animal species have a dietary pantothenic acid requirement of between 5 and 15 mg per kg diet. If the rumen is functioning normally, the ruminal microflora will synthesise enough pantothenic acid to satisfy ruminant needs. Research data indicates that the vitamin synthesis decreases when the diet is high in cellulose, but increases when higher quantities of easily soluble carbohydrates are provided.

Requirements for swine (NRC, 2012) range from 7.0 to 12.0 mg per kg diet. The highest requirement, at 12 mg per kg diet, is for young pigs and breeding animals. Apparently there is great variation in pantothenic acid requirement between breeds and between animals of the same breed. High fat levels may increase pantothenic acid requirement in pigs, while it has been suggested that high dietary protein decreases the requirement for pantothenic acid.




The pantothenic acid requirement for poultry varies between species, ranging between 2.2 and 15.0 mg per kg diet. For growth and reproduction the various species require between 10 and 15 mg per kg diet (NRC, 1994).

For chicken egg production the pantothenic acid requirement is very low (2.2 mg per kg diet) compared to a requirement of 10 mg per kg diet for growth and reproduction (Hoffman - La Roche, 1989). Requirements are based on typical consumption levels. When dietary energy density is increased, intake is reduced; thus, higher dietary concentrations of pantothenic acid and other vitamins are required.

Biotin


The chemical structure of biotin includes a sulphur atom in its ring and a transverse bond across the ring; biotin is 2-keto-3, 4-imadazilido-2-tetrahydrothio-phenevaleric acid, a monocarboxylic acid with sulphur as a thioether ulinkage. The rather unique structure of biotin contains three asymmetric carbonations, and therefore eight different isomers are possible. Of these only one, D-biotin, exhibits vitamin activity. The L-biotin stereoisomer is inactive.

Biotin crystallises from water solution as long, white needles. Free biotin is soluble in dilute alkali and hot water, and practically insoluble in fats and organic solvents.

Biotin exists in natural materials in both bound and free forms, much of the bound biotin being apparently unavailable to animal species.


Biotin is absorbed as the intact molecule, partly in the small intestine and, in pigs, partly from the hind gut.

The main functions of biotin include carboxylation, gluconeogenesis and protein synthesis. Therefore, biotin is essential for growth, the maintenance of epidermal tissues and reproduction.

Occurrence

Biotin is present in many foods and feedstuffs. The richest sources of biotin are royal jelly, kidney, yeast, blackstrap molasses, peanuts and eggs. Most fresh vegetables and some types of fruit are fairly good sources. Maize, wheat, other cereals, meat and fish are relatively poor sources. Biotin is available as a commercial product in spray-dried or triturate form. It is a fine powder, off-white to brownish in colour, stable in air but sensitive to light and humidity.

Requirements

In ruminants, the products of ruminal fermentation pass through the intestinal tract, where synthesised vitamins can be absorbed. The extent of biotin synthesis in the rumen can be affected by diet; e.g., feeding urea to cattle increases ruminal biotin content.

The dietary biotin requirement for breeding swine (NRC, 2012) is estimated at 0.20 mg per kg diet, and for growing pigs at 0.05 to 0.08 mg per kg diet. Biotin requirement is difficult to establish due to biotin variability in feed content and bioavailability. Estimated biotin requirements for various poultry species vary from 0.10 to 0.30 mg per kg diet (NRC, 1994). In poultry it has been demonstrated that polyunsaturated fats, fatty acids, ascorbic acid and other B-vitamins may influence the requirement for biotin.

Under conditions of nutritional or environmental stress, biotin requirement in broilers may be higher than 180 µg/kg diet.

In breeding hens, biotin is an important factor for hatchability.

Folic acid


Folacin is the generic descriptor not only for the original vitamin, folic acid, but also for related compounds which exhibit folic acid activity on the qualitative level.




Much of the folic acid in natural feedstuffs is conjugated with varying numbers of extra glutamic acid molecules. Polyglutamate forms of folic acid, usually containing between three and seven glutamyl residues ulinked by peptide bonds, are the natural coenzymes most abundant in every tissue examined. These folic acid glutamates appear to be a biologically inactive storage form, while synthesised folic acid is the monoglutamate form.

Folic acid is a yellow-orange crystalline powder, tasteless and odourless, and insoluble in alcohol, ether and other organic solvents. It is slightly soluble in hot water in the acid form and fairly soluble in the salt form.


Dietary folates, after hydrolysis and absorption from the intestine, are transported in plasma as monoglutamate derivatives, predominantly as 5-methyl-tetrahydrofolate. The monoglutamate derivatives are then taken up by cells in tissues by specific transport systems.

The urinary excretion of folic acid represents a small fraction of its total excretion. Faecal folic acid concentrations are quite high, often higher than intake. These represent not only undigested folic acid but, more importantly, the considerable bacterial synthesis of the vitamin in the intestine.

Folic acid is an essential vitamin for growth and the maintenance of normal health status in many animals. This vitamin has a sparing effect on choline requirement. Folic acid has also been reported to assist in the maintenance of the immune system.

Occurrence

Most feed sources contain predominantly polyglumatyl folacin. However, in seeds or fruit, which presumably store the vitamin, a considerable amount is present as a monoglutamate. A high proportion of monoglutamate forms of folacin are found in milk and soybeans.

Crystalline folacin is produced by the chemical industry for use in feeds and foods.

Requirements

Folic acid requirements have as yet been demonstrated only for calves, yearling cattle and lambs. No deficiency has been observed in dairy cows with normal rumen activity. This indicates that bacterial synthesis in the rumen covers metabolic requirements completely.

The publications relating to pigs (NRC, 2012) suggests a dietary requirement of 0.3 mg per kg diet for all classes of swine. Folic acid requirements for monogastric species are dependent on the degree of intestinal folic acid synthesis and utilisation by the animal.

Animals which practise coprophagy require less dietary folic acid, as faecal matter is a rich source of the vitamin.

Folacin requirements for the various poultry species range from 0.25 to 1.0 mg per kg diet (NRC, 1994).

Poultry on diets low in folacin develop deficiencies; although these can be produced by specific diets, maize, soybean meal and other common feedstuffs in a poultry diet used in practice should provide ample folacin under most conditions.

Vitamin B12 (cobalamin)


The term ‘cobalamins’ is used for compounds where the cobalt atom is in the centre of the corrin nucleus. Adenosylcobalamin and methylcobalamin are forms of vitamin B 12 occurring naturally in feedstuffs and animal tissues. Cyanocobalamin is not a naturally occurring form of the vitamin, but is the most widely used form of cobalamin in clinical practice, due to its relative availability and stability.

Vitamin B12 is a dark red crystalline hygroscopic substance, freely soluble in water and alcohol but insoluble in




acetone, chloroform and ether.


Vitamin B12 is bound to feed proteins in the diet. In the stomach, the combined effect of low pH and peptic digestion releases the vitamin, which is then bound to a nonintrinsic factor-cobalamin complex.

The passage of vitamin B12 through the intestinal wall is a complex procedure requiring the intervention of certain carrier compounds with the capacity to bind the vitamin molecule.

Storage of vitamin B12 in the body occurs principally in the liver; other sites are the kidney, heart, spleen and brain. Absorbed vitamin B12 is excreted principally by urinary, biliary and faecal routes.

Vitamin B12 plays an important role in transmethylation, which involves a close interaction with folicin. Transmethylation is essential for the synthesis of a number of amino acids, that of protein and that of tetrahydrofolic acid from folic acid. It is an essential part of the coenzyme involved in the metabolism of propionic acid. The vitamin participates in oxidation-reduction systems and is required in fatty acid metabolism.

Occurrence

Vitamin B12 is synthesised by many bacteria, but apparently not by yeasts or by most fungi.

Synthesis of vitamin B12 in the digestive tract is of considerable importance to animals. If sufficient cobalt is available, ruminants are independent of external sources of vitamin B12.

Foods of animal origin (meat, liver, kidney, milk, eggs and fish) are good sources of the vitamin. Kidney and liver are excellent sources, and these organs are richer in the vitamin if they originate from ruminants than from most non-ruminants. Plant products are practically devoid of this vitamin. Vitamin B 12 is produced by fermentation and is available commercially as cyanocobalamin for addition to diets.

Requirements

Vitamin B12 requirement in ruminant diets is closely associated with their cobalt requirement, since this trace mineral is a component of the vitamin B12 molecule. Ruminants have the capacity to synthesise the vitamin if supplied with adequate dietary cobalt (0.07 - 0.2 ppm) and if the rumen is functioning normally. Under typical conditions the rumen is functional for the synthesis of all B-vitamins at the age of 6 to 8 weeks. Therefore, only young ruminants in which the rumen is not fully developed would be expected to require a dietary source of this vitamin.

Requirements for swine vary from 5 to 20 µg per kg diet (NRC, 2012), young pigs and breeding animals having the highest requirement.

The vitamin B12 requirements of various species are dependent upon the levels of several other nutrients in the diet. Excess protein increases the need for the vitamin, as does increased performance level. Vitamin B 12

requirement seems to depend on the levels of choline, methionine and folic acid in the diet.

Requirements for poultry species vary from 3 to 9 µg per kg diet (NRC, 1994). Dietary requirement depends on intestinal synthesis and tissue reserves at birth. The vitamin B12 present in the caecum of the chicken is not available for absorption. This vitamin is present in significant amounts in the faeces. Therefore, coprophagy in deep litter sheds may provide a source of vitamin B12 for chickens.

Choline


Choline is ß-hydroxyethyltrimethylammonium hydroxide. Pure choline is colourless, soluble in water, formaldehyde and alcohol, and has no definite melting or boiling point. In the diet the vitamin is present mainly in the form of lecithin. Choline chloride is produced by chemical synthesis for use in the feed industry, and is available as 70% liquid or 25-60% dry powder.





Choline is absorbed from the jejunum and ileum, mainly by means of an energy- and sodium-dependent carrier mechanism. Only one third of choline ingested appears to be absorbed intact. The remaining two thirds is metabolised by intestinal microorganisms to trimethylamine, which is excreted in the urine. Choline forms a considerable part of a labile methyl pool capable of contributing methyl groups for the biosynthesis of methionine and other methylated compounds, including purines and pyrimidines. It is a precursor of acetylcholine, which is formed by a reaction with acetyl-CoA by the enzymatic action of choline acetylase.

Occurrence

All natural fats, and, hence, feeds containing fat, contain some choline, but it is largely absent from fruit and vegetables. Maize is low in choline, with wheat, barley and oats containing approximately twice as much choline as maize. For the purposes of feed supplementation a chloride salt is produced by reacting the alkaline base with hydrochloric acid. Choline is available as chloride (86.8 %) and bitartrate (48 %) salts.

Requirements

Estimates of choline requirement are based on the assumption that diets contain an adequate level of methionine. The bioavailability of choline in feedstuffs, variation between individual animals and the effects of other dietary factors exert an influence on choline requirement: in addition to methionine and other sulphur amino acids, dietary factors such as betaine, myoinositol, folic acid and vitamin B12, moreover age, sex, energy intake and growth rate of the animals. Most animals can synthesise sufficient choline for their needs, provided that enough methyl groups are supplied. Dietary betaine can spare choline, since choline functions as a methyl donor by forming betaine. Folacin and vitamin B12 are also required for the synthesis of methyl groups and the metabolism of the one-carbon unit.

In contrast to monogastric animals, no requirement for choline has been established in ruminants, except in the case of milk-fed calves, where 260 mg choline per litre of synthetic milk has been shown to prevent signs of choline deficiency. The NRC (1989) suggests that milk replacers for calves should contain 0.26% choline.

Choline requirements in growing pigs range from 300 to 600 mg per kg diet, while adult swine require 1000 to 1250 mg per kg diet (NRC, 2012). Excess dietary protein increases choline requirement in young animals, and high fat diets aggravate choline deficiency and thus influence the requirement in growing animals.

Choline requirement in growing poultry of various species ranges from 500 to 2000 mg per kg diet. Adult species can probably synthesise the vitamin in adequate quantities, breeding quail being the exception. These require 1500 mg per kg diet (NRC, 1994).

Vitamin C


Vitamin C occurs in two forms: L-ascorbic acid (reduced form) and dehydro-L-ascorbic acid (oxidised form). Both forms are biologically active. The majority of the vitamin exists as ascorbic acid, only the L-isomer of which shows activity. Ascorbic acid is a white or yellow-tinged crystalline powder. Vitamin C is the least stable and, therefore, the most easily destroyed of all the vitamins. It is more stable in an acid than in an alkaline medium.


Vitamin C has been demonstrated, in guinea pigs and man, to be absorbed in the intestine by means of an active Na+-dependent, energy requiring, electroneutral, carrier-mediated transport mechanism. The site of absorption is the wall of the duodenal and proximal small intestine. Ascorbic acid is excreted chiefly in the urine, and in small amounts via sweat and faeces. The urinary excretion of vitamin C depends on body stores, intake and renal function.

Absorbic acid is involved in a number of biochemical processes. However, the exact role of this vitamin in the physiology is not fully understood, since no coenzyme form has yet been detected. The most clearly established functional role of vitamin C is in collagen biosynthesis. The metabolic role of the vitamin is believed to include reactions involving electron transfer in the cell, metabolic oxidation of amino acids including tyrosine, metal ion metabolism by means of its reducing and chelating properties, carnitine synthesis, stimulation of the phagocytic activity of leucocytes and of the reticuloendothelial system, and the formation of antibodies, activity as a natural




inhibitor to potently carcinogenic nitrosamines, and the synthesis of corticosteroids in the adrenal glands.

Occurrence

The principal sources of vitamin C are fruit and vegetables, but some foods of animal origin, such as liver and kidney but not meat, contain quite substantial amounts of the vitamin. Ascorbic acid in feedstuffs is easily destroyed by oxidation. Supplementation with vitamin C is not recommended for common livestock species (ruminants, poultry, swine and horses) under normal management and feeding regimes.

Requirements

Vitamin C requirement is raised by pregnancy, lactation, thyrotoxicosis, increased metabolism, decreased absorption, stress or unfavourable environmental conditions (McDowell, 1989). In domestic animals such as swine, poultry, ruminants, horses, vitamin C is synthesised within the body. In chickens, biosynthesis takes place in the kidney.

Healthy animals under normal conditions do not respond to supplemental vitamin C, and hence there is no recommended requirement established by the NRC (2012) or the ARC (1981). However, some research has suggested that under certain environmental conditions the pig may not be able to synthesise enough ascorbic acid for maximum growth. On the basis of various studies, Marks (1975) proposed vitamin C requirements (mg per kg diet) for poultry and swine as follows: poultry 50-60; starting pigs 300; finishing pigs 150. Itze (1984) proposed that calves require 250 mg vitamin C per day.

4.4. 3.4.4. Vitamin-like substancesSome compounds, such as myo-inositol, carnitine, lipoic acid, coenzyme Q and polyphenols, exhibit biological activity in most animal species. Another group of substances, including pangamate, laetrile, gerovital and orotic acid, are not dietary essentials and are more properly termed pseudovitamins. In this chapter myo-inositol, carnitine and the essential fatty acids will be discussed, since these three substances act as vitamins in some species.

Myo-inositol (Inositol)


Myo-inositol is a water-soluble growth factor with no known coenzyme function; evidence suggests that this substance is not a true vitamin for most species. Inositol exists in nine forms, and is a white, crystalline, water-soluble compound with a sweet taste, stable in the presence of acids, alkalis and heat to about 250 °C.


Myo-inositol is absorbed from dietary sources by means of active transport, or may be synthesised de novo from glucose. Its function is not fully understood, but its biochemical functions probably relate to its roles as a phospholipid component of membranes and lipoproteins. Moreover, myo-inositol reduces liver lipids when the diet is low in protein and fat (McDowell, 1989).

Occurrence

The most concentrated dietary sources of myo-inositol are foods consisting of seeds, such as beans, grain and nuts, the best animal sources being organ meals.

Requirements

There are no known dietary requirements for myo-inositol in farm animals. In ruminants, the synthesis of myo-inositol by microorganisms in the digestive tract, in addition to dietary sources, is presumably sufficient to meet requirements.

Carnitine





Carnitine is a very hygroscopic compound, easily soluble in water. Carnitine exists as L-carnitine and D-carnitine.


Most animals can synthesise L-carnitine from methionine and lysine in the liver and kidney, but both humans and animals need an additional dietary supply. Free carnitine is excreted in the urine. In contrast to many watersoluble vitamins, carnitine is not carried in the blood in any tightly bound forms. Under normal conditions carnitine deficiency is unlikely, so no nutritional requirements have been established, but, under certain conditions, carnitine deficiency is manifest.

L-carnitine is required to transport long-chain fatty acids into the matrix compartment of mitochondria from the cytoplasm for subsequent oxidation by the fatty acid oxidase complex for energy production. It acts as a coenzyme in carnitine-acyl-carnitine-transferase.

It also serves a function in several other physiological processes: lipolysis, thermogenesis, ketogenesis, possibly the regulation of certain aspects of nitrogen metabolism, etc.

In carnitine deficiency, fatty acid oxidation is reduced, and fatty acids are diverted into triglyceride synthesis, particularly in the liver. (Baumgartner and Blum, 1993, after Harmeyer, 1992).

Occurrence

The L-carnitine content of plant-based feedstuffs is generally considerably lower than that of feed of animal origin. Of the digestible L-carnitine in animal feed 50-80% is absorbed in the digestive tract.

Requirements

Carnitine is universally present in biological systems, functioning as a vitamin for lower forms of life. Dietary supplements of L-carnitine may be required in young animals which are only just beginning to synthesise the coenzyme, and also in animals under stress, high-performance animals, animals fed low L-carnitine diets and animals receiving high-fat diets. The recommended dosages of L-carnitine in animal nutrition are given in Table 15.

4.14. ábra - Table 15. Recommended dosages of L-carnitine in animal nutrition*




Essential fatty acids


The essential fatty acids (EFA) originally comprised linoleic, linolenic and arachidonic acid, but arachidonic was later found to be synthesised from linoleic. In the natural environment double bonds of natural fatty acids are normally found in the cis form, but in hydrogenated fats and oils higher concentrations of trans fatty acids are found. Three common families of unsaturated, 18-carbon fatty acids and one family of unsaturated, 16-carbon fatty acids are known. The polyunsaturated fatty acids are liquids at room temperature. Linoleic acid is a colourless oil which melts at -12 °C and is soluble in ether, absolute alcohol and other fat solvents and oils.


In monogastric animals, after fat absorption the fatty acid composition of body fat is directly related to the fatty acid composition of the feed supplied. In ruminants, however, PUFA are hydrogenated to a great extent by ruminal microorganisms, resulting in more saturated body fat in the animal.

EFA have two recognised functions: as membrane components assisting in the maintenance of the functional integrity of these membranes, and also as precursors of the prostaglandins. Symptoms of EFA deficiency include retarded growth, dermal lesions, fragile capillaries, increased water loss through the skin, immune-incompetence resulting in easy infection, reproductive failure including sterility, disrupted parturition, increased perinatal mortality, and cardiovascular defects.

Occurrence

Vegetable oils derived from maize, soybean, cottonseed, peanut and certain other plant types are excellent sources of essential fatty acids: sunflower oil contains 75 % linoleic acid; yellow maize is the major source of linoleic acid in most feed formulate for swine and poultry; corn oil, soybean oil and cottonseed oil all contain about 50% linolenic acid; and linolenic acid is also high in forage lipids.

Requirements

Most species have a dietary requirement for linoleic acid, while others (e.g., fish) require linolenic acid. The various EFA differ in their capacity to prevent signs of EFA deficiency; this depends on the animal species




concerned. For most species, linolenic acid does not relieve dermal signs of EFA deficiency completely, even if given at high levels. For young ruminants, the main supplementation concern is that milk replacers should contain adequate concentrations of EFA.

To what extent linoleic acid (18:2 omega-6) and linolenic acid (18:2 omega-3) are essential in the diet depends on the animal species. The EFA requirement of most mammals can be met by linoleic acid and its family of polyunsaturated acids. A number of factors influence the development of EFA deficiency; requirements for EFA arc summarised in Table 16 (McDowell, 1989).

4.15. ábra - Table 16. Essential fatty acid requirements for various animals a,b

4.5. 3.4.5. Vitamin interactionsVitamins can seldom be considered as individual nutrients in isolation; they show a wide range of interactions with each other and with other factors, including nutritional ones. Interactions between vitamins take several forms and involve the processes of absorption, metabolism, catabolism and excretion. One vitamin may be required for the optimal absorption of another. The fat-soluble vitamins compete for absorption, and excesses of one may induce deficiencies of others by depressing their absorption. Types of interactions include vitamin-vitamin, mineral-vitamin, fibre-vitamin, protein and/or amino acid-vitamin, fat-vitamin and drug-vitamin. Only those interactions of principal importance with respect to animal nutrition will be discussed in the following sect1.

Vitamin A

Vitamin A and other vitamins

When both vitamins A and D are consumed in excessive amounts, vitamin A appears to mitigate vitamin D toxicity. In rats, for example, large doses of vitamin A have been shown to reduce hypercalcemia and the deposition of calcium in soft tissues caused by high doses of vitamin D (hypervitaminosis D). In chicks, excessive dietary levels of vitamins A and D have an antagonistic effect on plasma calcium, phosphorus and acid phosphatases. The exact mode of action is not known, but it has been suggested that vitamin A protects against vitamin D toxicity through increased mucopolysaccharide and collagen turnover.

Interactions between vitamins A and E are usually benefícial, but interactions between the two vitamins with




potentially negative effects have also been observed. Studies in the field of animal science indicate that high levels of vitamin A increase vitamin E requirement. Results attained with chicks show that the interaction between vitamin E and high doses of vitamin A enhances the oxidation of dietary vitamin E prior to intestinal absorption.

High levels of vitamin A have an adverse effect on the action of vitamin K, but the mechanism by means of which this occurs is not clear: a general effect of nonpolar lipid absorption or a specific vitamin/vitamin antagonism may be responsible. It is uncertain whether vitamin A influences the intestinal synthesis and absorption of vitamin K or other factors.

Vitamin A and minerals

Studies with rats have demonstrated that zinc-deficient animals exhibit low serum vitamin A levels despite adequate dietary levels of vitamin A. This suggests that mobilisation of vitamin A from the liver is impaired by zinc deficiency. Speculation remains as to the mechanisms underlying this impaired vitamin A metabolism in zinc deficiency and/or feed restriction. In several studies it has been concluded that, if liver vitamin A levels are normal, the absorption of vitamin A and its transport to the liver are not impaired, but zinc deficiency per se may affect the synthesis of retinol-binding protein (RBP) in the liver.

Studies on vitamin A deficiency have shown that liver and spleen iron increase concomitantly with a decrease in serum iron and haemoglobin. It appears that the mechanism of interaction between vitamin A and iron causes an impairment in the mobilisation of iron from the liver and/or the incorporation of iron into the erythrocyte.

Vitamin D

The interaction between vitamins A and D was discussed in the previous sect1. Vitamin D also interacts with several other dietary nutrients. The results of several studies on pigs have shown that isolated soya protein depresses bone calcification. In another study on pigs it was observed that adding up to 3 g per kg magnesium oxide to a vitamin D-deficient basal diet increased blood magnesium by 0.18 mg per 100 ml, but when 125 μg ergocalciferol per pig was also given the resulting elevation of blood magnesium concentration was three times higher.

An interaction between vitamin D and cholesterol has also been demonstrated; for example, adding coconut oil or cholesterol to the diet has been shown to elevate serum cholesterol in growing-finishing pigs; this can be prevented by adding either ergocalciferol or cholecalciferol to the diet. Several authors have suggested that vitamin D be used to increase the deposition of unsaturated fatty acids in fat depots and intramuscular fat

Vitamin E

Vitamin E and other vitamins

A beneficial interaction between vitamins E and A has been demonstrated at both extremes of vitamin A nutrition. Vitamin E can contribute to the alleviation of the symptoms of both hypovitaminosis and hypervitaminosis A. Vitamin E apparently spares vitamin A in several ways: by protecting it from oxidation in the gut; by increasing its absorption; by improving its utilisation; and by increasing its storage.

A number of researchers have studied the interactions between retinol and tocopherols. High dietary retinol concentrations depress the absorption of tocopherols, whereas inadequate dietary tocopherols may disrupt the utilisation of retinol. These interactions are of minor significance in the requirement for each nutrient, but tocopherols generally also exert a protective effect on retinol.

Vitamin E and minerals

In some instances it has been found that, in conditions of vitamin E deficiency, certain forms of injectable complexed iron, used for treating anaemia in piglets, can cause severe bruising, a rise in serum aspartate aminotransferase, or death, as ferric iron imposes a severe strain on redox systems in pigs. Iron hypersensitivity has been observed among piglets from sows receiving a PUFA-rich diet depleted of tocopherols. Protection from iron intoxication is possible by means of intramuscular injection of α-tocopherol, selenium or synthetic antioxidants. Studies on interactions between vitamin E and zinc in chicks have shown that a low-zinc diet (5 μg per g) causes severe skin lesions, joint abnormalities and lipid peroxidation. Supplementation of zinc-deficient diets with antioxidants such as vitamin E significantly decreases the severity of the dermal and joint lesions. The




interaction between zinc and vitamin E is believed to occur at the membrane level. Zinc apparently protects against peroxidative damage and promotes membrane integrity. Since vitamin E serves a dual role in protecting membranes against peroxidation and maintaining membrane structure, zinc and vitamin E may act synergistically to preserve cell membrane integrity.

The interrelationship between vitamin E and selenium has been discussed in sect1 3.3.

Vitamin K

Vitamin K-vitamin A and vitamin K-vitamin E interactions were discussed in a previous sect1. An indication of a vitamin D-vitamin K interaction has been demonstrated in several studies: results indicate that vitamin K supplementation decreases the elevated glycolytic activity of rat erythrocytes induced by a toxic dose of vitamin D. Abawi and Sullivan (1989) observed mortality in broiler chicks caused by an interaction between vitamins A, E and K. The results of this study suggest that in some instances higher supplemental levels of vitamins D and K improve performance in poultry fed high levels of vitamins A and E.

Vitamin B6

Interrelationships between vitamins C and B6 have been observed. Earlier studies demonstrated that the ingestion of high amounts of ascorbic acid increases the degradation of vitamin B6 to 4-pyridoxic acid in humans.

Several studies have demonstrated impairment in the absorption of vitamin B12 in vitamin B6-deficient rats.

Pantothenic acid

Pantothenic acid is necessary for the metabolic reactions involving biotin. This vitamin may also be necessary for the efficient utilisation of vitamin C.

Vitamin B12

Some studies in the field of animal science have shown interactions between vitamin B12, riboflavin and pantothenic acid. It has also been observed that riboflavin can partially replace the vitamin B12 requirement of rats and chicks due to a structural similarlity between the two vitamins: both contain the benzimidazole moiety.

Choline

Many research studies on rats, humans, chicks and turkey poults suggest an interrelationship between methionine, choline and inorganic sulphur. A study by Lovett et al. (1986) showed the effect of interactions between methionine, choline and sulphate on average daily weight gain and feed-to-gain ratio in weaning swine. Adding choline, methionine, sodium sulphate or choline plus methionine to the basal diet does not improve weight gain. When sodium sulphate plus methionine or sodium sulphate plus choline is added, daily weight gain increases and feed conversion improves. The addition of all three supplements has been shown not to cause any further increase in weight gain.

Vitamin C

Vitamin C and other vitamins

Several studies have indicated that in rats small amounts of ascorbic acid increase the conversion of carotene to vitamin A, while larger amounts have no effect, or even decrease its utilisation. Vitamins C and E are both antioxidants and protect other substances in the body, including other nutrients, from oxidative destruction. Since vitamin C is water-soluble, it is assumed to exert its hypothesised protective effects in the aqueous phase, while it is supposed that vitamin E, a fat-soluble substance, does so in the lipid phase. In vitro evidence exists that vitamins C and E have synergistic antioxidant properties. Vitamin C also regenerates tocopherol from the tocopheroxyl radical, thus restoring vitamin E to its active antioxidant form. Consequently, vitamin C can contribute to the control of lipid peroxidation.

It is known that interrelationships between vitamin C and the B-vitamins exist at tissue level, and the urinary excretion of vitamin C is affected in animals deficient in thiamin, riboflavin, pantothenic acid, folic acid and biotin. Interaction exists between vitamin C and carnitine too. Carnitine is synthesised from lysine and




methionine and is dependent on two hydroxylases, both containing ferrous iron and L-ascorbic acid.

Vitamin C and minerals

According to literature data, high dietary vitamin C protects chickens from much of the growth-depressing activity of toxic levels of salts of cobalt, selenium, vanadium, and cadmium (Hill, 1979). Mercury toxicity has been shown to be increased by the addition of 0.2% ascorbic acid, but not 1.0% ascorbic acid, to the diet.

In ascorbic acid deficiency, the mobilisation of storage iron is impaired and, similarly, excess ascorbic acid results in a marked improvement in the removal of iron from haemochromatosis patients with desferrioxamine. The interaction between ascorbic acid and selenium is less clear. Research has indicated that ascorbic acid depresses manganese superoxide dismutase and increases copper superoxide dismutase activity in the heart in rats. The effect of ascorbic acid on manganese metabolism is much less pronounced than the effect on this of dietary copper, which in turn affects manganese metabolism to a lesser extent than does iron.

Essential fatty acids

Parakeratosis in pigs is well documented; this is a disease involving an interaction between zinc and EFA. It is aggravated by the same factors which aggravate EFA and zinc deficiency. Hydrogenated coconut oil, which competitively inhibits EFA metabolism, elevates the level of dietary calcium, thereby inhibiting the absorption and utilisation of zinc and excess copper in the diet. When these exacerbating factors are eliminated or counteracted, disease symptoms disappear. Hence, reduction in calcium intake, supplementation with zinc and feeding with oils rich in PUFA are all beneficial with respect to parakeratosis. Copper supplementation also results in increased synthesis of monounsaturated non-EFA, which, by inference, causes a decrease in linoleic acid metabolism. Thus, with marginal zinc intake, copper should be considered detrimental to EFA metabolism, and may induce metabolic EFA deficiency if present in excess. Copper is documented as a physiological antagonist of zinc, and this appears to be reflected in its effect on fatty acid metabolism.

Oleic acid is non-essential but, when present in excess, competes with linoieic acid for further metabolism and also destabilises membranes.

Test questions:

1. Classify the most important vitamins and characterize them briefly.

2. Give the definition of “optimum vitamin nutrition”.

3. List the fat- and water-soluble vitamins.

4. List the types of vitamin interactions.

Recommended reading

Hoffman-La Roche. 1979. Optimum vitamin nutrition. Periodical. Hoffman-La Roche, Inc. Nutley. N.J. USA.


McDowell, L.R. (Ed). 1989. Vitamins in animal nutrition. Academic. Press, Inc. Boston, USA.

Nutrient Requirements of Swine. 2012. National Research Council (NRC). The National Academies Press, Washington, D.C. USA

Pond, W.G., Church, D.C., Pond, K.R., Schoknecht, P.A. (Eds). 2005. Basic Animal Nutrition and Feeding. Published by John Wiley & Sons Inc.

5. 3.5. MINERALSThe minerals have a wide variety of functions in the body. As bone components they ensure the skeletal structure’s stability (Ca, P, Mg, Cu, Mn), similarly components of teeth, as well as they are part of certain organic compounds, such as proteins (P, S, Zn), lipids, which take a part in the structure of the muscular system,




organs and other soft tissues. The minerals are important in promoting the activity of numerous enzymes (Ca, P, K, Mg, Fe, Cu, Mn, Zn). In addition, they have specific functions in blood and in other body fluids (Fe, Cu). They have a role in maintenance the osmotic conditions , (Na, Cl, K) the acid-base equilibrium (Na, Cl, K), and they have a pronounced effect on the muscles and on the nerves’ conduction processes as well.

Up to present days more than 40 elements were detected from the animal body. Macro elements are in g/kg, microelements are in mg/kg or smaller μg/kg magnitude in the animal body. There are several important elements in the body (C, N, O, H, S) which are not belonging to minerals. In the Table 17 we can see the quantity of different kinds of mineral elements in the animal organisms.

4.5. táblázat - Table 17. We can see the quantity of different kinds of mineral elements in the animal organisms

Macroelements (g/kg) Microelements (mg/kg)

Ca 15 Fe 20-80

P 7 Zn 10-50

K 2 Cu 1-5

Na 1,6 Mo 1-4

Cl 1,1 Se 1-2

S 1,5 I 0,3-0,6

Mg 0,4 Mn 0,2-0,5

Co 0,02-0,1

This grouping is the most spreadable form but at the minerals there are a lot of other different grouping forms. Nowadays one of the best and the most acceptable grouping is created by Anke, et al., 1996 (Table 18).

4.16. ábra - Table 18. Groups of trace and ultra-trace elements for animal and man




5.1. 3.5.1. MacroelementsCalcium and phosphorus

The ash content of the animal body contains more than 70% of calcium and phosphorus. We discuss these two elements together because their effects and functions are connected. 98% of the Ca content is in the bones and bonded to phosphorus in hydroxyapatite crystals. The remaining 2% is divided between the organs and the tissues.

Ca is needed in blood coagulation processes, muscle contraction, operation of cardiac muscle and neurotransmission processes, also an activator of several enzymes, and responsible for secretion of some hormones. 80% of the P can be found in the bones, and the rest of it is in the soft tissues. The P in the tissues is mainly in organic binders in the form of phosphoprotein, nucleoprotein, and phospholipid. The proper calcium and phosphorus supply basically depends on three main factors:

• Supply of quantity

• Ratio of Ca and P

• Presence on vitamin D

The above mentioned factors are closely related, but alone they are just necessary, but not sufficient conditions for balanced phosphorus/calcium supply (Hunt 1994). For example, if the absolute P supply is adequate, but if there is significantly more Ca in the feed, the P absorbance will not be adequate. The optimal Ca:P ration depends on many factors (e.g. species, the production), and therefore cannot be characterized by a single rate. If the feed’s Ca:P ratio, the role of vitamin D is particularly important. Inadequate Ca and P supply are causing growth and bone formation disorder mainly in fast-growing, young animals (poultry, pig), but deficiency symptoms are also not rare among juveniles of other species. A symptom of supply disorder can be osteitis with broken bones in older animals (osteomalacia) – mainly cows and sows (Thompson, 1998). In laying hens, the thinning of egg shell, brittle of the calcareous shell indicates the insufficiency of Ca-supply.

2/3-3/4 P of the grain yields can be found bounded to phytin. The Ca and Mg salts of phytic acid can not be degraded by the body’s own enzymes, but the rumen and colonic bacteria can. The phytase enzyme can be




found also in plants. The ruminant can utilise phytic P very well, but the young poultry and piglets utilises it poorly. The Ca and P products being fed are utilised equally, because their differences in solubility and dissociation. The difference of utilization can be quite big among the different formulations.

Magnesium

Magnesium is mediate between macro and micro nutrients. It’s nutrient cycling is closely related to Ca and P nutrient cycling. 70% of the Mg content of the body is in the bones, the smaller part is in the soft tissues intracellular. It is interesting but the strength of the bones depends on the magnesium content and not the calcium. Though only about 1% can be found in the extracellular space and in the blood plasma, this has an important role in developing isotonia (Miller, 1979). The decrease of Mg content in the blood plasma causes serious receptiveness for muscle cramps, the significant increase causes stupor. The Mg is an activator for several enzymes e.g. carboxylase and phosphorylase.

The feeds – except milk – contain more Mg than the demand, but the absorbance is low (e.g. 20%). The Mg provision can be determined from the Mg content of urine, because the surplus is excreted in urine. Completion can be solved with MgO in case of absence. Mg deficiency usually does not occur in Hungary, although some geographical areas can have a detectable lack. In western countries animal are particularly vulnerable at the beginning of the grazing season (spring) because of grass tetany (Grunes et al., 1970; Fontenot, 1979). Even in Hungary at high grass corps, abundant rainfall and intensive fertilization we cannot exclude the risk of grass-tetany.

Sodium, potassium, chlorine

They are discussed together, because these three elements play an important role in the maintaining of the body’s homeostasis. The most important electrolyte of the extracellular space is sodium, the potassium is of the intracellular space (Bia et al., 1981). Inside the cell the level of sodium is regulated by with an energy consuming (ATP) process (Na-K ionic pump). This is necessary because the excess of Na blocks the operation of several enzymes.

The Cl can be found both in the extracellular and intracellular space. It is most important function with sodium is to maintain the isotonia. In addition the chloride ion content of the blood plasma is the primary commodity of the hydrochloric acid formed in the stomach, and also the chloride ion is the activator of the α-amylase enzyme. The Na is excreted in high amounts with saliva as bicarbonate and because of this it supports the buffering capacity of rumen. The Cl in the gastric hydrochloric acid is efficiently reabsorbed from the gastrointestinal tract. So a very few loss can be counted. The excretion of these elements is happening through the kidneys, the lack of supplies can be reduced by tubular resorption. The Na and Cl loss through products (milk, egg) and secretions (perspiration) cannot be reduced.

The supplementation of Na and Cl only from plant derived feeds is not feasible. During supplementation it is should be considered that the excretion of Na is 2-3 times bigger than the excretion of Cl. Based on this the feed have to be complemented with salt so that the Na demand is 0,15-0,2% of the daily consumed dry matter. In case of deficit the production decreases which is accompanied with increased water intake. Overdose can cause problems if water supply is deficient. Especially the young turkeys are sensitive for salt poisoning.

The potassium supply can virtually meet all the needs, because the plant originated feeds contain more potassium, than the animal’s demands. Potassium overfeeding may only occur as technological mistake e.g. potassium fertilizer poisoning, the deficiency only occurs in extreme cases e.g. vomiting, diarrhoea (Tóth, 1994).

Sulphur

The sulphur evaporates during ignition, so it is not a component of ash. It is the component of the connective tissue, the cornea, some enzymes and hormones. Generally absorbs as a sulphur-containing amino acid, because the absorption of sulphate ions are very weak. Inorganic sulphur supplement is only appropriate in case of ruminant animals – preferably feeding with NPN materials – when sulphur and nitrogen ratio from the NPN feed is set to be 10:1 (Durand et al., 1980). Particular priority has the sulphur demand of the wool production. It has an antagonist effect against some micro elements in the soil and in the rumen.

5.2. 3.5.2. Microelements




Iron

It has the greatest amount in the body among the microelements, at the same time it’s role is also a lot. Formerly the iron had belongs to the macroelements, but later it has decided that it is a microelement. The iron’s most important role is the oxygen transport, since it is the component of the haemoglobin and the myoglobin (Figure 15).

4.17. ábra - Figure 15. The chelate part of the haemoglobin

The excretion of iron is very limited and well regulated in contrast with other elements. The body recycles the iron from the disintegrating red blood cells. The loss of blood, gestation and egg production increase the iron demand. Iron absorption is a very well regulated process. Only just the appropriate amount of demanded can pass through the intestinal walls. The extent of absorption depends on the iron saturation of the transporting protein (transferrin) in the blood plasma, and this is depends on the blood-forming organs’ iron absorbing capacity. The endothelial cells also contain ferrin; the absorbed iron is transmitted to the transferrin in the blood plasma. Thus ultimately the rate of the absorption is determined by the iron saturation of the endothelial cells ferritin (mucosal block). The intestinal endothelial cells’ ferrin will not be able to transmit the iron if the ferritin of the blood plasma is saturated with iron. The stored iron (ferritin) is always Fe (III), while the functional iron is always Fe (II).

The adult animal’s iron demand is covered by the feed. In contrast the milk hardly contains iron, so e.g. the squealers iron deficiency is 5-6 mg daily. Deriving from this they are having iron deficiency for the age of 7-10 days: anaemia develops. Add to this fact that compared to other animals, the piglet born with a poor iron store. The piglets’ iron deficient anaemia can be prevented only with special iron products. The most suitable iron supplement is the per os application pasta, syrup, suspension in the first period of sucking, later the powder formed iron supplement added to the feed (to premix). The parental iron supplement should be avoided because the risk of iron intoxication.

Copper

It has been long stated that the copper is needed for haemoglobin production. The copper’s role that the Fe(II) – Fe(III) transformation is a catalysed reaction by a copper dependent enzyme, the ferroxidase. The transformation of iron is presumed by the iron transport between ferrin and transferrin, after the stored form is Fe(III). If the copper is deficient, the absorption of iron is blocked. The copper is a component of some other enzymes (cytochrome c oxydase, tyrosinase).

The plants produced in sandy or high humous content soils are copper deficient because these kinds of soil can bind the copper.

Zinc

Zinc is an important component of several enzymes so it is important in the carbohydrate and protein metabolism, particularly essential in keratin synthesis. The parakeratosis skin affliction is known to be developing as a result of a secondary zinc deficiency in pigs. Young bovines and dairy cows epithelium regeneration disorder occurs landscape type connected in Hungary. In serious cases the zinc deficiency, which occurs in regions with calcareous soil, can cause reproductive disorders mainly in male animals. The supplementation may be solved well with premixes in pigs and poultry stocks.




Iodine

The importance of iodine is that 75% of the body’s iodine stock can be found in the thyroid gland as component of thyroid hormones (thyroxin, triiodothyronine). These two hormones are the regulators of the metabolism activity. From the producing point of view the restrained iodine supply leads to weight gaining, the increased amount provides a good background for milk production. Some kinds of plants are hindering the uptaking of the iodine (radish, brussels sprout, savoy cabbage). The lack of the iodine causes goitter which was a hugh problem in the former centuries, where the soil haven’t contented enough iodine (Vermiglio and Sidoti, 1990.). Nowadays the problem is solved with a simply thing. Put iodine into the salt.

Manganese

The manganese can be found mainly in the liver, but it occurs in skin, muscles and in bones as well. The absence causes partly growth and bone formation, partly reproduction disorders appear. The background of the bone formation disorders is that the Mn is the component of the glycosyltransferase which is important in cartilage formation process. It refers to it’s role in skeletal development that the deficit disorder of it causes perozis. The reproductive disorders are manifesting in maturity, irregular ovulation and degeneration in coelomic epithelium. The calcium and iron content of the feed interfere the manganese absorption, thus contributes in manganese deficiency.

Selenium

This microelement was described first in 1817, and it was named after the Greek goodness of the moon. In the 1930’ the selenium was first described as a toxic agent. It has been found that it cause toxicosis, because crops grown in certain alkaline soils had a high content of selenium. Later it was found that some disease, which can be treated with vitamin E e.g. liver necrosis, exudative diathesis, white muscle disease of calves and lambs, are essentially a consequence of selenium deficiency, and with a quite small amount of selenium these diseases can be cured (Combs and Combs, 1986.). Nowadays the selenium is known to exert its biological effect so that it constitutes the active site of a Se-containing enzyme the glutathione peroxidase, which enzyme protects membrane’s phospholipids polyunsaturated fatty acids form the oxidative damage. Se supplementation can be done both with inorganic (sodium selenite) and with organic (selenomethionine, selenocysteine) selenium. It is should be noted that in ruminant animals a part of the inorganic selenium is transformed into insoluble selenium salts. The overdose can lead to toxicosis, which results in hepatic and reproductive disorders. The high amount of superphosphate fertilizer may reduce the selenium content of plants through sulphur selenium antagonism.

Test questions:

1. 1. How can we grouping the mineral elements?

2. 2. What are the roles of the mineral elements in the body?

3. 3. What kinds of elements play a role in the maintaining of the body’s homeostasis?

Describe them!

4. 4. Why the iodine is so important?

Recommended reading

Fekete, S. Gy. (Ed). 2008. Veterinary Nutrition and Dietetics. Foundation for the Hungarian Veterinary Science. Budapest, Hungary.





5. fejezet - 4. MEASUREMENT OF THE UTILIZATION OF THE PROTEINS/AMINO ACIDS AND ENERGYIn vivo and in vitro digestibility of amino acids

A distinction must be made between digestibility and availability of amino acids.

Digestibility of an amino acid is the proportion of the total ingested that has been absorbed.

However, the availability of each amino acid is that part of the total amount in the feed which is actually supplied to the sites of protein synthesis.

Because the measurements of the availability of amino acids are very difficult, and the methods are not accurate enough, moreover, they are very expensive; the present chapter is focusing on in vivo and in vitro digestibility methods.

1. 4.1. IN VIVO DIGESTIBILITY OF DIETARY PROTEIN AND AMINO ACIDS1

1.1. 4.1.1. Digestibility of amino acids in pigsFaecal digestibility of protein (amino acids)

Nutrient digestibility, including also protein digestibility can be determined most accurately by animal trials.

A prerequisite for evaluating the digestibility via animal trials is to separate faeces from urine, as failing this the chemical composition of faeces can not be determined precisely. Bearing this in mind the trials are usually carried out with males (barrows) and the animals are housed individually in so-called metabolic cages for the duration of the trial. The metabolic cages differ in size for the weaning piglets (7-25 kg), the growing-finishing pigs (25-105 kg) and the large animal (105 kg plus).

The methodology for digestibility studies is described by Gundel and Babinszky (1988). Trials are still being carried out according to their suggestions, and the methods are similar for all age groups.

The study consists of two periods, an adaptation period and a collection period. In order that the digestive apparatus can adapt to the test diet and to ensure that also the faeces collected originate from the test diet, the 5-days collection period needs to be preceded by a 7-9-days adaptation period. Animals must be weighed individually at the start and end of the adaptation period (the end of which is also the start of the collection period) and also at the end of the collection period. Daily rations are determined on the basis of live weight. During the collection period the amount of diet consumed and of faeces excreted should be weighed individually every day. When the test diet is fed alone the trial is a simple digestibility test. Having determined the chemical composition (nutrient content) of the diet and of the faeces by laboratory analysis the digestibility coefficients can be calculated for each nutrient - also for protein or amino acids (AA S) - with the following equation:

11* This sect1 of the chapter is based on the following publication: Babinszky, L. 2008. The concepts of ileal digestible amino acid and ideal protein in swine and poultry nutrition. In: S. Gy. Fekete (Ed): Veterinary Nutrition and Dietetics. Chapter VII: Digestibility of nutrients. „Pro Scientia Veterinaria Hungarica” Budapest. 119-146.


4. MEASUREMENT OF THE UTILIZATION OF THE

PROTEINS/AMINO ACIDS AND ENERGY

In case the test diet can not be fed on its own - which is true of most proteins sources - a so-called differential digestibility test should be conducted. The differential test actually consists of two adaptation and two collection periods. In the first adaptation and first collection period we feed the so-called basal diet which can be fed alone, and in the subsequent second adaptation and second collection period we feed the test feed either on top of the basal diet or replace with it a part of the basal diet (e.g. 10, 15 or 20 % of it). In case of a differential digestibility test the digestibility coefficients (DC) of the nutrients can be calculated with the following equation:

In case the number of periods in the study is increased further, the digestibility coefficients of the test feed nutrients are calculated by extrapolating the differential digestibility coefficients resulting from each trial period to the 100 % portion of the test feed.

If for some reason it is not possible to measure accurately the feed intake and to perform a quantitative collection of the faeces, an indicator (marker) should be mixed to the diet in order to determine the digestibility of the nutrients. This process is called the indicator (marker) method. When this method is applied, the digestibility of nutrients can be deducted from the change of proportion of a nutrient (e.g. AA) and the indicator in the faeces compared to their proportion in the diet.

It is very important to avoid in the study an indicator deleterious for the animal, or one that could affect the digestive processes, neither should it be capable of being absorbed and be digested in the intestinal tract. Further criteria are that the indicator should move on relatively evenly in the intestinal tract, it should mix well in the feed, and its quantity should be easily determined by chemical analysis both in the diet and in the faeces.

Chromium(III)-oxide (Cr2O3) is a typical indicator, but ferric(III)-oxide (Fe2O3), barium-sulphate (BaSO4), or titanium-dioxide (TiO2) are also viable options.

Beside the foregoing so-called additive indicators other feed ingredients can also be used as indicators, such as the HCl insoluble ash content in the diet. The accuracy of this method, however, is usually lower than that achieved by additive indicator studies - due to the low concentration of the HCl insoluble ash content of the pig diet.

The following equation is used for calculating the digestibility coefficient of nutrients when indicators are applied.




It should be noted, that the studies discussed in this sect1 will determine the so-called apparent digestibility, as for example the protein or AA excreted with the faeces originates not only from the indigestible or digested but not absorbed parts of the dietary protein, but also from the own N reserves of the animal body. This N portion is called endogenous N (endogenous protein).

When an adjustment is made for the endogenous N (protein), the result is the true digestibility of the protein.

The true digestibility of crude protein (N x 6.25) can be calculated as follows:

Ileal digestibility of proteins (amino acids)

With the need of more accurately meeting the amino acid requirement of pigs the study of ileal digestibility of amino acids has become an important area of research in the past fifteen years.

The digestibility of dietary proteins and amino acids used to be characterized with the apparent faecal digestibility coefficient - similarly to other nutrients.

However, the findings of digestion-physiology research works prove that the intestinal flora in the colon simultaneously synthesizes and catabolizes protein. This is the reason why the faecal digestibility of dietary proteins will in some cases underestimate, in others overestimates the real value.

In consequence ileal digestibility of proteins and amino acids is used in many countries. This method may seem to have a disadvantage in that it does not take into account the amount of amino acids absorbed from the large intestine.

The results of relevant studies show, however, that this is only an apparent source of error, as the various nitrogen bonds are absorbed from the postileal sect1 (colon) almost exclusively in the form of ammonia, thus they do not participate in protein synthesis and are simply excreted with the urine. From the point of animal nutrition therefore the amount of amino acids absorbed until the end of the small intestine (ileum) is important only.

Differences among apparent, standardized and true ileal digestibility

It is generally accepted that the apparent ileal amino acid digestibility coefficients are dependent on the amino acid content in the assay diet.

Apparent ileal amino acid digestibility increases curvilinear with increasing amino acid content in the test diet.

The word „apparent” refers to the fact that the coefficients are not adjusted for endogenous nitrogen and amino acid losses. The limitation to the use of apparent ileal amino acid digestibility is that digesta collected at the end of the small intestine contains large quantities of endogenous protein. As illustrated in Figure 16, the endogenous amino acid losses can be separated into a basal (minimum) and an additional specific loss. The basal loss is non specific and related to dry matter intake. However, the specific loss is related to inherent factors in feedstuffs, e.g. fiber and anti-nutritive factors etc. (Pack et al., 2002).

5.1. ábra - Figure 16. Origin of amino acid losses at the terminal ileum




The amounts of basal endogenous protein or amino acid losses in ileal digesta can be determined by different methods such as feeding protein free diet, feeding diets containing protein sources that are assumed to be 100% digestible with complete absorption of amino acids and the regression technique.

If corrections are made for basal endogenous amino acid losses, the standardized ileal amino acid digestibility coefficients (SDC) can be calculated with the following equation:

Standardized ileal protein and amino acid digestibility has the advantage over both apparent and true digestibility in that it represents a fundamental property of the individual feedstuffs, namely standardized digestibility values include any variation of the endogenous fraction related to the feedstuff itself.

The effect of dietary amino acids on their respective apparent, standardized and true ileal digestibility coefficients can be seen is Figure 17.

5.2. ábra - Figure 17. Expression of apparent, standardises and true ileal amino acid digestibilities as a function of amino acid intake

Determination of ileal digestibility with different techniques

There are several methods for measuring the ileal digestibility of amino acids. The majority of these methods require surgical operation prior to the start of the trials to obtain digesta (chyme) from the terminal ileum from which to determine the ileal digestibility.

Ileal digestibility studies without cannulation techniques

Post mortem digestibility studies: before the expansion of cannulation techniques the only possible means for determining the amount of nutrients absorbed from the intestinal sect1s was the analysis of digesta samples collected from the intestine after the trial animals were slaughtered. The disadvantage of this method is, that the animals can be used in a single trial only. As for the reliability of the trial results the biggest shortcoming of the




method is, that the electric shock or other impulse occurring at the moment of killing will cause a shedding of mucosa in the intestine to an extent that it may provide incorrect information about the digestibility of proteins and amino acids. For this reason the method is used extremely rarely by now.

Ileo-rectal anastomosis (IRA): the process based on ileo-rectal anastomosis allows total digesta collection without the insertion of a cannula. With this surgical method the end of the ileum is connected directly to the rectum with the removal of the cecum and colon (Figure 18) and thus the digesta from the ileum is excreted through the rectum and can be collected quantitatively. A doubtless advantage of the process is the possibility of collecting digesta directly, but it has the disadvantage, that by removing a part of the intestinal tract the nutrient and vitamin supply of the body suffers and also the electrolyte balance can be easily upset.

5.3. ábra - Figure 18. Stages in the surgical procedures used to establish an ileo-rectal anastomosis in pig

Simple T-cannula method: the simplest method for representative digesta collection is enabled by the so-called T-cannula, for the application of which several research teams have developed various procedures (Figure 19). A common characteristic of all procedures is that they necessitate the use of an indicator (marker), because the T-cannula is not suitable for quantitative digesta collection.

5.4. ábra - Figure 19. Simple T-cannulation technique in pig




The collection of the digesta at regular intervals (at least 4 times daily) during the collection period is enabled by a polythene bag attached to the cannula.

Re-entrant cannulation: this procedure allows quantitative collection of the ileal digesta. The method essentially involves the insertion of an ileum-ileum or ileum-caecum cannula in the animals subject to the purpose of the study (Figure 20).

These cannulas can be perceived as an artificial intestinal sect1 with a valve, leading the ileal digesta outside the body permitting its collection and quantitative weighing; following which the entire digesta or part of it is returned to the intestinal tract. Disadvantages of the method are the complexity of the required surgery, and also the risk of cannula blockage, which may primarily be attributed to inadequate intestinal peristalsis at the cannula insertion point and/or to the high fiber content of the test diets.

5.5. ábra - Figure 20. Re-entrant cannulation technique in pig

PVTC (post valve T-cannula) method: the procedure was developed by Leeuwen et al (1988). With this surgery operation a specially shaped T-cannula is inserted in the caecum, upon the opening of which the end of the ileum




is sucked into the cannula by the vacuum generated and with the control of the ileo-caecal valve the entire digesta is voided outside. When the cannula is shut the digesta passes through the gut without interruption. A major advantage of the method is, that the necessary operation is relatively simple, the peristalsis of the small intestine is undisturbed and it allows quantitative collection (Figure 21).

The digesta is collected in a polythene bag attached to the cannula.

5.6. ábra - Figure 21. PVTC (post valve T-cannula) technique in pig

Mobile bag technique: Petry and Handlos (1978) were among the first to apply the mobile bag (or nylon bag) technique in the evaluation of swine feeds.

The ileal digestibility of crude protein and amino acids can be measured with the improved PVTC procedure. In this method the test feed samples following their in vitro or in vivo incubation are placed in small bags and introduced into the GIT through the duodenal cannula, and are then collected with the digesta which is voided through the PVTC cannula. The bags are cleaned, weighed, and then their homogenized content is analyzed. Advantages are the rapidity, accuracy and relatively small substance requirement of the procedure. Another important benefit is, that already at the initial stages of the e.g. plant selection work - when the amount of test substance is still very limited - the digestibility of protein and/or AA of a given line or cross combination can be determined with quite high accuracy. A notable disadvantage of the method is, that due to the small amount of test substance remaining in the bag, nutrients which require relatively large samples for their quantitative assay (e.g. Weende analysis) can not be determined with this procedure.

The difference between faecal and ileal digestibility

When evaluating the digestible amino acid content the question arises, whether ileal digestibility provides a more precise information about the digestibility of amino acids than the data based on faeces collection. Studies show, that there is a considerable difference for instance between the faecal and ileal digestibility of the crude protein, lysine, methionine and cystine content of full fat soya, which difference should definitely be considered in the diet formulations (Table 19).

5.7. ábra - Table 19. Digestibility of crude protein and amino acid content of full fat soya in growing pigs




Overall it can be concluded that the digestibility measured along the full length of the intestinal tract (faecal digestibility) shows a higher value than ileal digestibility does. The difference between the two sets of data is primarily attributable to the energy supply of the colon microflora, because when energy is the limiting factor in the colon, the microorganisms utilize the indigestible protein content of the digesta as a source of energy, and consequently the apparent faecal digestibility of protein will be higher. If there is no energy deficiency in the colon, the microbes produce bacterial protein from the N compounds of the digesta by way of de novo synthesis. Thus the protein excretion via faeces will increase and the digestibility coefficient will be lower.

Imperfectly conducted feed processing procedures may result in major changes of the digestibility of crude protein and amino acids. Results of growing pig trials from Holland show, that while the faecal digestibility of crude protein, lysine, methionine and cystine in soybean meal did not reflect the defects of toasting (the digestibility of crude protein and amino acids was the highest in the over-treated feedstuffs) its effect on ileal digestibility was obvious (Table 20).

5.8. ábra - Table 20. Effect of toasting on the faecal and ileal digestibility of crude protein, lysine, methionine and cystine in soybean meal (%) (van Weerden, 1985)

The data of the Dutch work in reference and of other studies as well prove that when the objective is the evaluation of the quality of dietary protein, the measurement methods based on ileal digestibility are considerably more sensitive than those based on the collection of faeces.

Application of the ideal protein concept in swine nutrition

The necessity of applying the so-called ideal protein concept both in diet formulation and in the substitution of protein sources has become increasingly important in recent years. The development of the "ideal protein" theory for swine has been a subject of work in the UK already since the early eighties. Those studies, however, were still based on the total amino acid requirement of the animals. Still earlier, several authors already expressed the amino acid requirement of pigs by listing the necessary amount of each amino acid as a percentage of lysine. Loen (1966) was among the very first to determine the total lysine requirement of fattening pigs in relation to the starch value, and to specify the amount of the other amino acids in percentage of lysine.

In the meantime an adequate database was generated for the ileal digestible amino acid content of various feedstuffs as well, and consequently the concept of ideal protein could also be modified, i.e. it could be made more accurate. Lange (1992) highlighted the fact, that when the ileal digestibility of amino acids is used in the calculation, the profile of ideal protein is partially altered. The biggest change is seen in the case of threonine (Table 21). This can be explained by the fact, that the threonine portion of ileal endogenous protein is relatively high. The high level of endogenous threonine is the reason why the digestibility of threonine measured at the end of the small intestine remains significantly below the ileal digestibility of lysine.




5.9. ábra - Table 21. Essential amino acid profile in ideal protein (lysine: 100 %) based on the total and ileal digestible amino acid content (Wang and Fuller, 1989)

The amino acid profile of ideal protein differs in maintenance from that in growth (production). According to the relevant studies the ideal protein needs to contain a higher portion of methionine and cystine, and also threonine and tryptophane to meet the amino acid requirements for maintenance, compared to the needs of weight gain (Table 22). The practical implication of this is that the ratio of these amino acids should be increased in the ideal protein in order to cover the amino acid requirement of maintenance, because with the increase of live weight also the protein and amino acid requirement of maintenance increases.

5.1. táblázat - Table 22. Essential amino acid profile in ideal protein (lysine: 100 %) for maintenance and weight gain (Henry, 1993)

Maintenance Weight gain

LYS

THR

TRP

MET+CYS

ILEU

LEU

VAL

PHE+TYR

100

139

29

147

44

74

52

124

100

69

18

53

63

115

77

124

With the purpose of meeting the amino acid requirements more accurately, Baker and Chung (1992) proposed to specify the amino acid composition of ideal protein for three different body weight categories (between 5 and 100 kg). The recommendations are summarized in Table 23.

5.2. táblázat - Table 23. Percentage of essential amino acids in ideal protein (lysine: 100 %) for pigs in the growing and fattening stages (Baker and Chung, 1992)

Live weight, kg 5-20 20-50 50-100

LYS 100 100 100




THR

TRP

MET+CYS

ILE

LEU

VAL

HYS

PHE+TYR

65

18

60

60

100

68

32

95

67

19

65

60

100

68

32

95

70

20

70

60

100

68

32

95

In addition to weaned piglets and growing-finishing pigs, the literature also provides recommendations for the percentage composition of amino acids in the diet of pregnant and lactating sows (Table 24). These recommendations should be taken into account in the diet formulations.

5.10. ábra - Table 24 The ideal pattern of amino acids during pregnancy and lactation (Close, 1995)

Application of ileal digestible amino acids in the formulation of swine diets

In the field of practical feeding it is also important to know the relationship between the fattening performance and the method of diet formulation, i.e. whether the diet was formulated on the basis of faecal or ileal digestibility of the crude protein. According to Belgian work there is a very strong correlation between the ileal digestibility of crude protein and the weight gain and feed conversion rate (FCR), while the strength of relationship between faecal digestibility and the two parameters mentioned is only medium or even looser (Table 25).

5.11. ábra - Table 25. Correlation between the ileal and faecal digestibility of dietary crude protein and the weight gain and FCR of growing - finishing pigs (Dierick et al., 1987)




These data allow the conclusion, that the amino acid requirement of growing and finishing pigs can be satisfied better if the requirements are specified as ileal digestible amino acids. There has been an increasing number of publications reporting of such studies in latter years.

As for the diet formulation it should also be noted, that the ileal digestible amino acid content represents an advantage over the faecal digestibility data only in case the diet does not consist of corn and extracted soybean meal exclusively, because when the amino acid requirements of pigs were determined, the trial animals were fed with a corn and soybean meal based diet (NRC, 1998). In all other cases (e.g. when feeding multi-component diets, or in the substitution of protein sources) using the data based on ileal digestibility may yield practical benefits also in the diet formulations.

Another important fact to know in the formulation of swine diets is, that also the energy supply of the animals is crucial for the adequate utilization of amino acids. A multitude of relevant trial findings prove that the growth performance and the chemical composition of the carcass (the protein: fat ratio; i.e. the quality of the meat) is influenced not only by the genetic potential, but also by the amino acid: energy ratio of the diet.

As lysine is generally the first limiting amino acid for pigs, all efforts should be made in the diet formulations to achieve the best possible lysine: energy (digestible energy, DE) ratio in the interest of enhancing protein deposition.

The trial results prove, that during the first phase of fattening (25-60 kg) the lowest level of fat deposition can be expected in the case of an

0.6 g ileal digestible lysine / MJ DE ratio. In the second phase of fattening (60-105 kg) this ratio decreases to the level of 0.5 g ileal digestible lysine / MJ DE.

To summarize the information on the ileal digestibility of amino acids in pigs the following conclusions can be drawn:

• Considering the methods presently available, the amino acid requirements of pigs can be best met when the ileal digestible amino acid content of the feedstuffs is used in the diet formulation.

• The ileal digestibility of amino acids can be determined by several methods. The relevant studies show, that all cannulation procedures provide reliable data. In the selection of the method, however, the composition of the diet, the age of the animal, and the skill of the team conducting the study should also be considered.

• As evidenced by the trial data, ileal digestibility is a considerably more sensitive method than the method based on collection of faeces, and consequently such data signify any potential defects of feed processing more reliably than the faecal digestibility data.

1.2. 4.1.2. Digestibility of amino acids in poultryDetermining the digestibility of amino acids with different methods

Nutritionists already in the sixties were concentrating on the question of how to determine the digestibility of amino acids in poultry diets and meet more accurately the amino acid requirements of poultry. No significant progress has been made in this field in the last 30 years, and only a relatively small number of papers have been published.




The development of cannulation techniques, however, seems to offer a new approach for solving the problem. In the past decades the various recommendations and requirement levels applied in the diet formulations used to be calculated on the basis of total amino acid content in the field of poultry nutrition as well. On the basis of research results it has also become apparent, that the amino acid requirement of poultry could be best satisfied, if - similarly to swine - the calculations were made with the so-called available amino acid content of the diets.

The availability of each amino acid is that part of the total amount in the diet which is actually supplied to the sites of protein synthesis. However, the current methods for assessing the amino acid availability of feedstuffs for pigs and poultry have drawbacks:

1. Measurements of AA flow from the intestine into the portal blood are delicate and laborious while their reliability needs to be proved. This method is not appropriate for the evaluation of a large number of raw materials.

2. Growth evaluations give only an estimate of the availability of the limiting AA, and their results depend on many other factors which also influence the growth of pigs and poultry, e.g. excesses of other amino acids.

The recent results show that the use of digestibility values in practical diet formulation is the closest to a system based on availability.

There are several methods available for determining the digestibility of amino acids in poultry.

Method based on the collection of excreta (dropping digestibility)

One of the most frequently used digestibility studies is the method based on the collection of excreta. When this technique is applied (Figure 22), the excreta voided through the cloaca is collected quantitatively, and then chemical methods are used to separate the faecal and urinary nitrogen content of the excreta from each other. An apparent disadvantage of the method is, that its accuracy is limited, furthermore it does not take into account any potential bacterial activity in the caecum and colon.

5.12. ábra - Figure 22. Dropping digestibility (intact bird)

Method based on the removal of the caeca (caecectomyzation)

In the application of this method the paired caeca of the birds are removed eliminating thereby the potentially distorting effect of bacterial activity taking place in the caecum (Figure 23).

The surgery is performed in anesthesia. A disadvantage to be noted is, that after the caeca are removed, bacterial activity may still be present in the remaining caecal stump. A similar problem should be expected in the colon as well. Moreover it also necessitates the assumption that the amino acid content of the urine is negligible. The application of the method therefore requires numerous assumptions to be made before the digestibility data can be accepted.

5.13. ábra - Figure 23. Dropping digestibility (caecectomized bird)




Methods based on cannulation techniques

Determining the digestibility by collecting the faeces (colostomization): application of this method requires cannulated birds. During surgery after the abdominal cavity is opened an incision is made in the colon at about 15 mms from its sphincter, and then a simple T-cannula is inserted in the terminal colon (Figure 24). The advantage of the method is, that there is no need to separate the faeces from the urine by chemical methods. The resulting digestibility coefficients have a good repeatability and the data represent the apparent digestibility of amino acids well. When the nitrogen and amino acid content of the faeces is adjusted with the endogenous portion, the true digestibility of amino acids can be calculated (see sect1 4.1.1.). Birds prepared in this manner are also suitable for conducting N balance studies.

5.14. ábra - Figure 24. Faecal digestibility (cannulated/colosomized/bird)

Determining the digestibility by collecting the ileal digesta: some researchers argue, that similarly to swine it is the ileal digestibility of amino acids which provide the most reliable data for poultry species. There are two methods known for determining the ileal digestibility:

1. Although no cannulated birds are required for the first method (post mortem digestibility studies) it is still necessary to discuss it here, as ileal digesta is collected during these studies. In these studies the birds are killed, and the digesta collected from the last sect1 of the small intestine is subjected to the necessary chemical assays. The problems pertaining to the post mortem studies are the same as those discussed with swine (sect1 4.1.1.).

2. The cannulation technique appears to be the most reliable method for determining the ileal digestibility of amino acids. During the surgery operation preparatory to these studies the ileum is separated from the postileal sect1 of the GIT, and then a simple T-cannula is inserted in its terminal sect1 (Figure 25). The cannula allows the quantitative collection of the digesta and the calculation of the apparent ileal digestibility of the amino acids. Similarly to the method based on the collection of faeces, adjustment for endogenous nitrogen (amino acid) can be made in this case as well, which will result in the true ileal digestibility of the amino acids (see sect1 4.1.1.).

It should be noted, however, that these procedures should only be conducted with adult birds; the various cannulas cannot be implanted into young birds.




5.15. ábra - Figure 25. Ileal digestibility (cannulated bird)

Digestibility of amino acids measured with different techniques

The digestibility coefficients determined with different methods may differ significantly from each other in many cases. Table 8 summarizes the results of the study conducted by Bragg et al (1969), who determined the digestibility of amino acids in sorghum using cannulated birds. Their data were compared to the results from digestibility studies based on the collection of excreta (dropping digestibility). The results of the trial series show, that in the case of some amino acids (lysine, cystine, threonine) there are major differences between the values measured by the two digestibility methods. Similar differences can be found in the ileal digestibility and dropping digestibility of amino acids in soybean meal also (Table 9) (Bielori and Iosif, 1987).

The data in Tables 26 and 27 therefore highlight the fact, that there may be significant differences in the digestibility of amino acids of various feed ingredients, depending on where, in which intestinal sect1 the values were measured.

5.16. ábra - Table 26. True digestibility of amino acids in sorghum based on the collection of faeces and excreta (Bragg et al., 1969)

5.17. ábra - Table 27. Ileal and dropping digestibility of selected amino acids of soybean meal (Bielori and Iosif, 1987)

At present there are relatively few data available on the ileal digestible amino acid content of various feed ingredients. The Dutch Central Bureau for Animal Nutrition (CVB, 1997) has published informative figures which can be used well in the diet formulations. Table 28 contains the total and ileal digestible amino acid content of some feed ingredients.

5.18. ábra - Table 28. Total and ileal digestible amino acid content (g/kg) of selected feed




ingredients (CVB, 1997)

It appears from the data presented also, that there are substantial differences in the digestibility of amino acids of certain feed ingredients.

Thus for instance, the digestibility of lysine in corn is only 61 %, while that in wheat is 83 %. Similar differences can be measured in the digestibility of lysine in meat and bone meal (73 %) and in fish meal (91 %). These discrepancies warn, that the amino acid requirement of poultry can be meet with more accuracy if instead of calculating with the total amino acid content of the feed ingredients, the digestible amino acid content is applied; as the birds are able to use for protein synthesis only that portion of the amino acids which was absorbed from the ileal sect1 of the GIT.

When discussing the ileal digestible amino acid content, the question may arise as to whether the differences between the ileal digestible amino acid content and the digestibility values based on collection of excreta also exist when complete concentrates are fed. The data in Table 29 show, that the differences seen in the case of feed ingredients should be expected for compound feed as well (Tossenberger and Babinszky, 1998).

5.19. ábra - Table 29. Total and apparent digestible amino acid content of grower diet for broilers* (Tossenberger and Babinszky, 1998)

In an other study on birds fed compound feeds no significant difference was found in the digestibility values determined by colon and ileum cannulated birds. However, digestibility values measured on the basis of excreta collection (intact birds and caecectomized birds) were significantly lower for all amino acids tested compared to the digestibility measured at the end of the ileum or colon. This finding can be attributed to urinary AA excretion. The use of ileum or colon cannulated birds can both be recommended for the purpose of determining the amino acid digestibility of poultry diets (Babinszky and Tossenberger, 2005).

Ideal protein concept in poultry nutrition

In poultry nutrition the optimal dietary protein allowance is one which equally satisfies the essential and non-essential amino acid requirements of the birds so that at the same time it contains no surplus of any of those amino acids (Babinszky and Vincze, 2002). Such a diet, however, can only be produced by synthetic or semi-




synthetic methods.

In practice, an allowance can be considered ideal, when its protein content is the closest to the optimal composition beside the use of the least expensive raw materials.

When the amino acid composition of the ideal protein allowance is determined, it should not be forgotten, that the diets must contain not only all essential amino acids but also the total quantity of non-essential amino acids pro rata to the energy content of the diet. This is necessary, because the deficiency of any essential amino acid, or of the total combined quantity of non-essential amino acids compared to the requirement will diminish the protein utilization. The lower protein utilization then leads to poorer growth rates and feed conversion rates. The composition of ideal protein is given in percentage relative to lysine for poultry nutrition as well.

When the amino acid composition is determined for poultry, however, most of the problems are encountered in the estimation of sulfur-containing amino acid requirements. The reason for this is the feathering which changes with age. It should also be noted, that further studies are needed to determine the ratio of some essential amino acids to lysine. Several trials are being conducted at present with this purpose. Table 30 provides a recommendation for the composition of ideal protein by age groups.

5.20. ábra - Table 30. Recommended ideal protein composition for broilers by age group*

Diet formulations on the basis of digestible amino acid concept

The application of the digestible amino acid content in the diet formulations can only be justified professionally when the associated benefits are realized in production also. For this reason it is especially important to become acquainted with the results of field trials how the performance of broilers and the economics of production changed when the diet was formulated on the basis of digestible amino acid content.

Rostagno et al. (1995) in their broiler studies fed three different compound feeds (HD, LD and LD+AA) both in the starter and in the finishing phase.

In the first treatment (control) the diet was formulated with a highly digestible amino acid content (HD). The diet fed in the second treatment contained a very poorly digestible amino acid portion (LD); while in the third treatment the diet of the second treatment was supplemented with crystalline amino acids on a digestible amino acid basis, so that the digestible amino acid content of the diet fed in this treatment equaled the digestible amino acid content of the control diet (Table 31).

5.21. ábra - Table 31. Nutrient content of the diets (%) (Rostagno et al., 1995)




The results of the broiler growing trial are summarized in Table 32. The trial data show, that when the amino acid content of the diet is poorly digestible, but it is supplemented on a digestible amino acid basis, the performance of the broilers will be at least the same as that achieved with a highly digestible amino acid containing diet, without harming the economic efficiency of the production. The application of industrially manufactured amino acids, however, should be preceded by economic calculations.

5.22. ábra - Table 32. Summary of results of the broiler growing trial (Rostagno et al., 1995)

In summary it can be concluded, that

1. The evaluation of dietary proteins is more accurate for poultry if it is described with the digestible amino acid content instead of the total amino acid content.

2. The amino acid requirement of broilers with high production potential can be met more accurately, when the digestible amino acid content is used in the diet formulation.

2. 4.2. IN VITRO DIGESTIBILITY OF DIETARY PROTEINThe determination of digestibility of nutrients (e.g. crude protein) by conventional methods requires large quantities of feed, a number of animals and considerable expenditure on equipment and manpower. Further, there is a considerable body of public opinion which is not in favor of animal experimentation, regardless of whether these trials are stressful to the animals.

Thus in last decades there has been an increasing interest in developing rapid laboratory methods for the study of digestion in pig and the evaluation of pig feeds.

In general it can be stated, that the in vitro methods are varying according to the enzymes employed, temperature and time of the reaction and the separation techniques used to obtain the digested fraction (Eggum and Boisen, 1991).




Generally in vitro methods are based on the degradation of feed samples, either by enzyme mixtures or by intestinal inocula (intestinal fluid), with recovery of the undegraded residue by filtration or centrifugation.

Protein digestibility is usually measured from the quantity of nitrogen or amino acids released by the enzymatic hydrolysis of protein sources. The more appropriate approach would be to use a two-step enzymatic system consisting of first digestion with pepsin in acid medium and subsequent enzymatic hydrolysis with pancreatin in alkaline medium.

Basically the methods for determination of digestibility of crude protein may be divided into two groups: in vitro and in vivo methods as it can be seen in Figure 26.

5.23. ábra - Figure 26. In vitro digestibility of crude protein

Many different in vitro methods have been developed for evaluating of dietary protein. By the 1950’s a single one step incubation method involving pepsin was in use (mono-enzyme method). This method has undergone various modifications, and has been used in particular to monitor the effect of heat treatments of feed. However, this method was not accurate enough.

The pH-drop and pH-stat assays are other simple methods for prediction of the digestibility. These techniques are based on pH-changes caused by proton liberation after purified porcine protease hydrolysis of feed protein peptide bonds. The pH-stat method was found to be highly reproducible in an inter-laboratory investigation involving six laboratories. However, the accuracy of this technique was also not good high (Eggum and Boisen, 1991).

Moreover, the above in vitro methods have been criticized as being too simplified, when considering the complex digestion processes occurring in the different sect1s of the intestinal tract (Boisen, 2000).

Therefore several methods have been developed for a more representative simulation of protein digestion in the stomach and the small intestine. These are so called multi-enzyme methods which methods can be divided into two groups: incubation with or without intestinal fluid.

Several research groups have developed a method, which include incubation steps with enzymes and jejunal fluid from jejunum-cannulated pigs (Furuya, 1979, Büchmann, 1979).

The disadvantage of these methods is that cannulated animals are also needed.

Babinszky et al. (1990) supplemented pancreatin with amylase for improved starch degradation after removing lipids by pre-extraction with petroleum ether.

As an example, the multi-enzyme method of Babinszky et al. (1990) is described briefly.

Procedure A: about 1 g of sample material weighed to an accuracy of ± 0.1 mg, was incubated in a 100 ml centrifuge tube with 25 ml pepsin/HCl solution in a shaking water bath at 40 0C for 1.5 h. Then the solution was neutralized with 220 mg NaHCO3 and mixed. Potassium phosphate buffer (25 ml, 0.2 M/l, pH 6.8),




containing 4 g pancreatin and 4 ml amylase per liter, was added and the incubation was continued (at 40 0C, 1 h). After this incubation 5 ml Na2CO3 (100 g /l) was added and the tubes were centrifuged (15 min, 3500 x g). The liquid phase was decanted over nylon cloth (pore size 40 μm), the particles were rinsed back in the tubes with water, and then the centrifugation and filtration were repeated. The nitrogen content of the residue (undigested phase) was determined by the Kjeldahl method.

Procedure B: as an alternative to fat extraction of the feed samples prior to analysis by the in vitro procedure, 40 mg pancreatic lipase and 80 mg bile salts were added per liter of potassium buffer to improve fat hydrolysis. In this procedure B, after the pancreatin incubation 10 ml trichloroacetic acid (TCA) was added, and the contents of the tubes were mixed ant the tubes were centrifuged (15 min 3500 x g). After filtration the filtrate was collected. The residue was washed with 25 ml TCA and refiltered, and the filtrates were combined. The content of nitrogen in the filtrate was measured by the Kjeldahl method. To correct for the nitrogen content of the enzymes added, controls without feed samples were also analyzed.

Calculations of the digestible coefficient of protein:

Digestible coefficient:

100-(A/Bx100)

Where: A: crude protein content of residue, precipitate(%)

B: crude protein content of feedstuffs (%)

Babinszky et al. (1990) found an improved correlation to the content of fecal digestible crude protein when using pre-extraction. Correlation coefficients between in vivo and in vitro data are:

Feedstuffs: r=0.93

Compound feed: r= 0.85

It can be summarized, that the simple in vitro digestibility methods could have considerable potential for improving and optimizing the formulation of diets for livestock. However, the accuracy of these methods should be improved. The complex (multi-enzyme) in vitro methods can attempt to simulate closely the processes of digestion with higher accuracy (Boisen, 2000). These methods have a potential for supplying important information about the digestion processes.

According to Boisen (2000) in the future, computer-controlled in vitro models of the digestive tract may become a valuable instrument for fine-tuning actual feeding according to the predicted actual requirements.

3. Test questions:1. Give the definition of “ideal protein” concept.

2. List the techniques which are used for the determination of amino acid digestibility in pigs.

3. List the techniques which are used for the determination of amino acid digestibility in birds.

4. List the in vitro digestibility methods for protein.

4. Recommended readingBabinszky, L., van der Meer, J.M., Boer, H., den Hartog, L.A. 1990. An in vitro method for prediction of the digestible crude protein content in pig feed. Journal of the Science of Food and Agriculture. 50: 173-178.

D’Mello, J.P.F. (Ed). 2002. Amino acids in animal nutrition. CABI Publishing, Wallingford, UK.

Engelhardt, W.V., Leonhard-Marek, S., Breves, G., Giesecke, D. 1995. Ruminant physiliogy: digestion, metabolism, growth and reproduction. Ferdinand Enke Verlag Stuttgart, Germany.




Fekete, S. Gy. (Ed). 2008. Veterinary Nutrition and Dietetics. Foundation for the Hungarian Veterinary Science. Budapest, Hungary.

Leeuwen van P., L. Babinszky, M.W.A. Verstegen, J. Tossenberger. 2000. A procedure for ileostomisation of adult roosters to determine apparent ileal digestibility of protein and amino acids of diets: Comparison of six diets in roosters and growing pigs. Livestock Production Science 67: 101-111.

Moughan, P.J., M.W.A. Verstegen, M.I. Visser-Reyneveld (Eds). 2000. Feed evaluation principles and practice. Wageningen Pers. Wageningen.NL.

Tisch, D. 2005. Animal Feeds, Feeding and Nutrition, and Ration Evaluation., Delmar, USA.


6. fejezet - 5. ENERGY METABOLISM OF FARM ANIMALS1. 5.1. ENERGY TERMSLife of animals depends to a large extent on sufficient supply of energy. Energy is needed for maintaining the organism in a good state as well as for production. Homeotherm animals, moreover, may use energy to maintain their body temperature at the desired level if the environmental temperature is too low. Whereas most plants obtain their energy from part of the sun’s radiation, animals derive their energy from degradation of organic compounds. The animals derives energy by partial or complete oxidation of carbohydrates, fats and proteins ingested and absorbed from the diet or from breakdown of glycogen, fat or protein stored in the body (van Es and Boekholt, 1987). By complete combustion in a bomb calorimeter these compounds release their energy as heat-carbohydrates about 17 KJ/g, proteins about 24 KJ/g and fats about 39 KJ/g. In the animal body this degradation, of course, concerns only the digested part. For protein the degradation is incomplete as the nitrogen is released as urea or uric acid and excreted with the urine.

Utilization of ingested feed energy by animals involves several kinds of losses (Figure 27).

6.1. ábra - Figure 27. Flow diagram of energy terms

Not all of the feed can be digested and absorbed, the remainder is excreted in the faeces.

In animals with symbiosis with microbes in the forestomachs and/or large intestine energy in gaseous form (CH4, H2) is lost.

Also losses, as heat, occur when the absorbed nutrients are used for production of ATP needed for maintenance, physical work and synthetic purposes. Furthermore, when this ATP is used for maintenance and work or for the conversion of absorbed nutrients into tissue, milk, eggs, and wool, part of its energy becomes heat.

As a result of the losses of energy in faeces, urine and combustible gases the gross energy of the feed (GE) is not a good measure for the energy available for the metabolism of the animal.

Gross Energy (GE): gross energy is defined as the energy liberated as heat when feed, feces or animal tissue is fully oxidized by burning a sample completely in a bomb calorimeter (see more details in Chapter 1).


5. ENERGY METABOLISM OF FARM ANIMALS

Digestible Energy (DE): digestible energy is the energy of the feed (GE) less the energy of the faeces. Digestible energy can be determined relatively easily by performing a digestion trial (see Chapter 4 sect1 4.1.1) in which an animal is fed a known amount of the dietary energy, faeces are collected, and the GE content of the feed and faeces is determined.

It is called apparent digestible energy as distinct from the truly digestible energy because the faecal energy includes that of undigested feed as well as that of metabolic products derived from body tissues.

True DE is determined by measuring, in addition, the energy in faecal excretions (metabolic faecal energy) of an animal that is fasting or being fed a diet presumed to be completely absorbed, such as milk or eggs, or in some cases the animal is fed intravenously (Pond et al., 2005). The amount of excretion is then subtracted from total faecal excretion of the fed animal. However, it should be noted that this determination is not feasible with most herbivorous animal species and is done only in practice with poultry (Pond et al., 2005).

Energy lost in the faeces accounts for the single larges loss of ingested energy. In pigs the losses are 20 %, in ruminants 40-50% in the case of roughage and 20-30% in the case of concentrates. In horses faecal losses account for about 40% of the energy ingested.

DE can be determined also by calculation, using a regression equation according to (Schiemann et al., 1971):

DEs (KJ/kg) = 24.2X1+39.4X2+18.4X3+17.0X4

Where:

DEs = digestible energy content of the feed for swine (KJ/kg feed)

X1 = digestible protein (g/kg feed)

X2 = digestible fat (g/kg feed)

X3 = digestible fiber (g/kg feed)

X4 = digestible N-free extract (g/kg feed)

According to relevant literature data it can be stated that digestible energy can be affected by different factors. These are as follows:

• minor effects: age, gender, genotype of animal;

• major effects: composition of the diet (fiber content of the diet), feeding level, preparation of feeds.

Digestible energy is commonly used to evaluate feedstuffs for pigs, rabbits, and horses.

Total Digestible Nutrients (TDN): the total digestible nutrients method has been used for many years to estimate the energy content of a feed. This method sums all the fractions that are digestible. The amount of each different component that makes up an animal’s feed is determined; then the amount that subsequently ends up in the faeces is determined. From this the amount of each of the components digested is determined.

The TDN can be calculated by the followings formula:

TDN = Digestible crude protein + Digestible crude fiber + Digestible N-free extract + 2.25x Digestible ether extract (fat)

The ether extract is multiplied by 2.25 in an attempt to adjust its energy value to reflect its higher caloric density.

Metabolizable energy (ME) is defined as GE of the feed minus energy lost in the faeces (FE), urine (UE), and combustible gases. ME is that portion of feed energy that is available for metabolic processes in the animal.

To measure ME for ruminants it is necessary to collect faeces, urine and methane. Faeces and urine are collected in digestibility trials from animals placed in metabolism cages provided with a device for collecting urine. For measuring methane produced a respiration chamber is needed. When no respiration chamber is available, methane losses can be calculated as 8% of the GE intake or from the amount of digested carbohydrates. Methane contains 31.8 KJ per gram. ME is commonly used to evaluate feedstuffs for pigs and poultry. Since gas



production of pigs is negligible, therefore to measure ME for swine it is necessary to collect in metabolism cages only faeces and urine.

ME for swine can be determined also by calculation, using a regression equation according to (Schiemann et al., 1972):

MEs (KJ/kg) =21.0X1+31.4X2+14.4X3+17.1X4

Where:

MEs = metabolizable energy content of the feed for swine (KJ/kg feed)

X1 = digestible protein (g/kg feed)

X2 = digestible fat (g/kg feed)

X3 = digestible fiber (g/kg feed)

X4 = digestible N-free extract (g/kg feed)

Because birds void urinary and faecal losses together, the ME values for poultry can be determined by standard digestibility procedures. Losses of combustible gases accruing as results of fermentation in caecum and large intestine of monogastric species are negligible.

The urine loss of energy results from the excretion of incompletely oxidized nitrogenous compounds associated with protein metabolism, primarily urea in mammals and uric acid in birds.

According to relevant literature data, the energy value of each gram of nitrogen excreted as urea is 23 KJ and as uric acid is 28 KJ. For this reason each gram of urinary nitrogen excreted by pig accounts for 28 KJ and in poultry 34 KJ.

To eliminate the variable protein (N) intake, in case of birds is recommended to make a correction to zero N-balance (MEn).

The apparent metabolizable energy (AME) for birds corrected to zero N-balance (AMEn) can be determined by calculation, using the followings regression equation according to Härtel et al., 1977

AMEn (MJ/kg DM) = -3.064+34.82X1+17.21X2+X3(18.52-31.2X4)

Where: AMEn = apparent metabolizable energy for birds, corrected to zero N-balance

X1 = crude fat (g/g DM)

X2 = crude protein (g/g DM)

X3 = N-free extract (g/g DM)

X4 = crude fiber (g /g DM)

Net Energy (NE) and Heat Increment (HI): net energy is obtained from ME by subtraction of heat increment. Thus NE differs from ME by the amount of heat lost as a results of chemical and physical processes associated with digestion and metabolism, i.e. the heat increment (HI). This energy term most accurately predicts the amount of energy that is going to be available for use by the animal for maintenance and productive functions. HI is also called specific dynamic effect.

The portion of NE used for maintenance is the energy expended to sustain the life processes of an animal. It serves for muscular work needed for minimal movement, maintenance and repair of tissues and to keep up the temperature of the body in cold environment.

The other part of NE (fed above maintenance needs for production) is the energy retained in tissue gain of growing or fattening animals or in milk or eggs produced, i.e. the caloric value of animal products. NE is the part of GE completely useful to the body.



Heat production of an animal consuming feed is composed of HI and heat used for maintenance. The energy needed for maintenance of a fasting animal (termed basic metabolic rate) is covered by breakdown of body reserves, mainly body fat and the energy equivalent of the decomposed body constituents is dissipated as heat.

Measuring of heat production

The heat production of an animal can be measured by direct calorimetry and by indirect calorimetry.

Direct calorimetry: direct calorimetry is simply in theory, but difficult in practice. In this method the heat production of animals can by determined by measuring heat loss via the separate channels of conduction, radiation, convection and evaporation, or by measuring the first three together in a direct calorimeter or combined with evaporation.

The weight of water circulated per unit time multiplied by the rise in its temperature gives the sensible heat loss. Due to the insufficient accuracy of this method nowadays mostly the direct calorimetry is used.

Indirect calorimetry: indirect calorimetry can be based on the measurements of O 2 consumption and CO2

production by the animal or in alternatively in terms of carbon and nitrogen balances used as indicators for heat production (Blaxter, 1989; Boisen and Verstegen, 2000). Nitrogen (N) balances can be determined from N in feed, faeces, urine and aerial NH3. For indirect calorimetry, the animal is housed in a respiration chamber for the quantitative measurement of gaseous exchange.

The heat production of animal can be calculated as follows:Mammals (Brouwer 1965):

HP (KJ) = 16.18 * O2 + 5.02 * CO2 - 2.17 * CH4 – 5.99 * N

Birds (Romijn and Lokhorst 1961):

HP (KJ) = 16.20 * O2 + 5.00 * CO2 – 1.59 * N

Where: O2, CO2, and CH4 represent volumes consumed or produced (liters) and N is urinary nitrogen (g).

2. 5.2. RESPIRATORY QUOTIENT (RQ)Because the animal body derives all its energy from oxidation processes, the magnitude of energy metabolism can be estimated from the exchange of respiratory gases, i.e. the ratio of the volumes of CO2 produced and O2

consumed, or the respiratory quotient.

The RQ value can be calculated as follows:

RQ=CO2produced (liter)/O2consumed (liter)

Respiratory quotients of selected nutrients can be seen in Table 33.

The metabolic interconversion of feedstuffs may also alter the RQ value. RQs considerably higher than 1 may be obtained when carbohydrate is being converted into fat, The RQ is lowered in the metabolic disorder of ruminants, known as ketosis, when fatty acids are not completely oxidized to carbon dioxide and water, and carbon and hydrogen are excreted as ketone bodies. RQ in birds may be below 0.7 since uric acid formation leads to lower this value than the formation of urea.

6.2. ábra - Table 33. Respiratory quotient of selected nutrients



In conclusion it can be stated, that RQ may provide valuable information about the metabolic processes in the animal body.

3. 5.3. CALCULATION OF NE CONTENT OF RUMINANT DIETSNE values are widely used in formulating diets for various ruminant species. Net energy values are also available for maintenance (NEm), gain (NEg), and milk production (NEl).

Net energy for maintenance (NEm), can be calculated according to Lofgreen and Garrett, 1963):

NEm, MJ/kg DM= 1.37ME – 0.033ME2+0.0006ME3- 4.686

ME, MJ/kg DM = 0.82 x DE

Net energy for gain (NEg), (Lofgreen and Garrett, 1963):

NEg (MJ/kg DM) = 1.42ME – 0.042ME2 + 0.0007ME3 – 6.904

ME, MJ/kg DM = 0.82 x DE

Calculation of Net energy for lactation (NEl), according to Moe et al., 1969:

NEl (MJ/kg DM) = 0.6032DE x (1-2df) - 0,502

Where: df: discount factor

Discount is a correction factor related to the fiber content of feedstuffs (df values can be found in the relevant feeding tables)

4. 5.4. FACTORS AFFECTING ENERGY METABOLISM AND ENERGY REQUIREMENTS OF FARM ANIMALS4.1. 5.4.1. Energy metabolismThe energy metabolism of livestock could be affected by many different factors. In the process of digesting and metabolizing energy, the greatest loss is fecal loss. Other losses are associated with metabolism losses. Energy lost through urine and microbial methane production in the GI tract will amount to about 10% of GE in ruminants, but less in most monogastric species. Losses after absorption can vary greatly, depending on level of intake, quality of diet, and other factors. Heat is produced as a result of microbial fermentation in the GI tract (heat of fermentation). Heat is also produced when nutrients are oxidized. This is referred to as heat increment (see earlier in this chapter). The larges heat increment is associated with the metabolism of proteins (amino acids), followed by metabolism of carbohydrates and then fats.



4.2. 5.4.2. Energy requirementsEnergy requirements are also influenced by many factors , like: age of animal, species and breed differences, neuroendocrine factors, miscellaneous factors (fasting, muscular training: hypertrophy of muscles, mental effort, which causes a slight increase in heat production, activity of animal, production level, environmental conditions, nutrient deficiencies, etc. Additionally, it should be noted, that the energy requirements are directly related to body surface area because heat is lost or gained in proportion to the body surface area exposed. Therefore, multiplying the body weight by factorial power (0.75 is commonly used) provides a very good estimate of surface area. This value is referred as metabolic body weight (BW kg 0.75).

5. 5.5. COMPARATIVE SLAUGHTER TECHNIQUEThe measurement of energy retention in growing and fattening animals by direct or indirect calorimetry is a very expensive and labor-intensive procedure. In addition to the serious technical background large highly qualified professional staffs is also required.

The comparative slaughter technique (CST) is another method for determining energy retention in animals. This technique requires that at the start and at the end of a trial, representative animals of each treatment are slaughtered and analyzed for dry matter, protein,

fat, and sometimes for energy. The energy content of the body can also be calculated from protein and fat data. The method is useful for chicken and pigs. But CST is also expensive when applied to large animals.

Accurate results are only be obtained when the time interval between the start and end of the trial is long (thus the weight change is large) and the number of animals per treatment is not too small, otherwise the influence of between animal-variation on the results could be large

(Boisen and Verstegen, 2000).

6. Test questions:1. Describe the flow diagram of energy terms.

2. Give the definition of digestible energy (DE) and metabolizable energy (ME) and describe how can be determined DE and ME.

3. Give the definition of net energy (NE) and describe how can be determined NE.

4. What is the difference between direct and indirect calorimetric methods?

7. Recommended readingBabinszky, L., Halas, V., Verstegen, M.W.A. 2011. Impacts of climate change on animal production and quality of animal food products In: Blanco, J. A. and Kheradmand, H. (Eds): Climate Change, Socioeconomic Effects. In Tech Open Access Publisher. 165-190.

Fekete, S. Gy. (Ed). (2008). Veterinary Nutrition and Dietetics. Foundation for the Hungarian Veterinary Science. Budapest, Hungary.

McDonald P., Greenhalgh, J.F.D., Morgan, C.A., Edwards, R., Sinclair, L., Wilkinson, R. (Eds). 2011. Animal Nutrition. Seventh edition. Pearson Education, Limited. Harlow, UK.

Pond, W. G., Church, D. C., Pond, K. R., Schoknecht, P. A. (Eds). 2005. Basic Animal Nutrition and Feeding.

Wood, JD., Rowlings, C. (Eds). 2011. Nutrition and Climate Change: Major Issues Confronting the Meat Industry. Nottingham University Press.


7. fejezet - 6. NUTRIENT REQUIREMENT OF BODY PROCESSES AND PRODUCTIVE FUNCTIONSNutrient requirements of farm animals

The farm animal uses the nutritive matters of the consumed feed for two purposes. The first and most important is to maintain living. The most of the nutrient content of the feed is used for maintaining life, and the residue can be used for other kind of production. In case of nutrient requirement, we can talk about the wide variety of nutrients. There is energy need, protein need, mineral need, vitamin need, and there is also fibre need for some animals. As it can be seen there is a wide variety of nutrient needs and the application area of them is also very diverse. It is important to distinguish the areas from each other because of the speciality of the operation of the animal body the different utilisation means different efficiency (Ranjhan, 2001). To eliminate this we can distinguish different nutrient requirements (life maintenance, growth- meat production, milk production, egg production, wool production, reproductive production, labour. In this lecture note because the lack of space we will not discuss all the types of requirement, we will only focus on key issues.

1. 6.1. THE NUTRIENT REQUIREMENTS OF MAINTENANCEThe basic of the production is that to keep the animal healthy and in good condition. Our primary task is to provide the required nutrient amount for maintenance, which the animal uses for several functions (consistent temperature of the body, surface tension, maintenance of electrical phenomena in the cells, the mechanical work in the cells, operations of organs, maintain muscle tone, basic body movements). The level of the life maintenance needs is determined by the basal metabolic rate (Bondi, 1987). The amount of nutrients spent on life maintenance considerable increases the costs of the production of animal products which can be moderated by the increase of the production because this will reduce the rate of the life maintenance nutrients per unit of animal product. It is always our goal to keep this value as low as possible.

1.1. 6.1.1. Energy requirement of maintenanceEnergy requirement of maintenance mean that amount of energy which is needed for the animal which is non productive, do not work, do not fast and it is in thermo-neutral environment to maintain the energy needs for the basic life phenomena (circulation, respiration, excretion, function of the nervous system, maintenance of muscle tone) (Thorbek and Henckel, 1976). It has to be taken into account that energy amount which is needed to sustain life: for take in and digest the feed, absorption of the nutrients and for the minimal movement needed to maintain health condition, and these also increase the need. This amount is affected by several factors.

• The most important is the body weight of the animal. The heat production of starving increases with the body weight (Klnadorf et al. 1981; Farell and Swain, 1977), but the heat production per unit decreases. Since with the increase of the volume decreases the surface per unit of volume, the most accurate result is achieved when we determine the energy need for body surface not for body weight. The problem with this is that it is difficult to determine accurately the body surface of the animals, so usually it is based on the body weight. The result in every case is that the animals with less weight produce more heat per body weight unit this is due to the fact that proportionally they have a large body surface and the metabolism is more vigorous.

• The age and the sex also effects on the maintenance energy need. The younger is the animal, the more heat is produced. The difference between the growing and the adult animal depends on the growth rate of the species. In case of the sex, the male animals have a better growth rate and their heat production is 10-15% higher than the female animals have. The extra requirement is maintained even after complete growth.


6. NUTRIENT REQUIREMENT OF BODY PROCESSES AND PRODUCTIVE FUNCTIONS

• The ambient temperature is also an important effecting factor. From the external factors the most influent factor is the temperature. All farm animal endeavours for isothermia, to maintain constant body temperature. The constancy of the body temperature is controlled by heat production and heat loss.

• The nutrition is also an affecting factor, because the body temperature of the feeding animal increases compared to a starving animal. This is partly due to that extra energy consumption which occurs with the intake of the feed, chewing of it, the transmission of it to the digestive tract, enzyme production and absorption of the nutrients. In addition it also contributes in the increase of energy need that the participation of nutrients in intermediate metabolism also needs energy.

• The energy need of the animals is affected by their movements as well. The standing and more significantly the motion also increase the energy need, compared to lying. Standing increases the energy need with 15% in mammals, 30% in poultry. The only exception of this is the horse, since it has a body structure that does not encumber the animal (Cunha, 1991). The energy surplus of motion mostly means extra cost for grazing animals. Those animals who graze require even 30-50% more feed than those who had not been out to pasture.

1.2. 6.1.2. Protein requirement of maintenanceThe sustaining of living requires not only energy, but protein as well, since as a result of the aging of cells the organism has to make up the lost protein. The deteriorating protein is partly excreted from the body with the faeces and partly with the urine. The nitrogen in faecal excretion has two parts. The endogenous nitrogen is from the proportion of nitrogen used for maintenance, while the exogenous nitrogen is from the indigestible nitrogen content of the feed. The nitrogen excreted by urinary also has a double origin. One part of it is from the life sustaining cell aging and so it is endogenous originated, while the other one is from the catabolism of the amino acid content of the feed, so it is exogenous.

2. 6.2. NUTRIENT REQUIREMENTS OF WEIGHT GAINThe body weight of the animal from the fertilization to the full growth occurs in accordance with a sigmoid curve, i.e. the growth of the fetus is small initially, later weeks prior to parturition and in the first half of juvenile age it is very intensive. Approaching the adult age the growth slows down, and after maturation it decreases drastically. This should be considered during feeding. The weight gain of the young animals is the consequence of the incorporation of protein and minerals, while in older age the amount of fat increases.

2.1. 6.2.1. Energy requirement of weight gainA significant proportion of the weight gain of young animals is made up by protein (40-50%). The incorporation of this protein is a very energy –intensive process, so it is essential to ensure to achieve the appropriate growth. The energy requirement of the growth is determined by the magnitude of weight gain and the composition of it (protein, fat). The energy efficiency of fat producing is regardless of age and species, the efficiency of it is 70-75%. In contrast with fat the protein synthesis is highly dependent on the age of animal (the older the worse) (Donato and Hegsted, 1985). For young animals the transformation efficiency can reach 65-70%, while this is barely 20-30% at the end of the juvenile age.

The fat/protein portion of weight gain also changes with age: the protein decreases, and the fat increases. The increase of fat production entails with the decrease of daily weight gain, since in case of protein synthesis the incorporation of one unit protein entails with the incorporation of four units of water. Of course in parallel with the decrease of weight gain the feed conversion also deteriorates.

2.2. 6.2.2. Protein requirement of weight gainThe impeccable amount of protein is essential for the young animals to exploit the genetic potential. The high daily weight gain and the efficient feed conversation only can be expected when the need of protein is fully satisfied (Campbell et al. 1985). In addition the protein supply affects the body composition of the fed animal. The protein requirement is affected by many factors:

The digestive characteristic of the animal: in case of different species, the differences between the digestive characteristic are due to bacteria. For ruminants, which live in symbiosis with a large amount of bacteria, the



dead bacteria are important protein source (it is an animal originated protein in terms of amino acid set) and it is available. This greatly facilitates the protein supply of the animal.

The biological value of the protein: it is determined by the amino acid set. The more similar it is to the body content to the animal, the more efficient it is used by the animal. This is partly because the animal original feeds always provide a better protein supply than the plant origin feeds.

The age of the animal: as time goes by the protein utilisation of the animal reduces. It follows directly that the younger is the animal the more efficient is the protein incorporation which should be used in animal nutrition. Besides the age the other important factor is the reach of the sexual maturity, since the feed utilisation efficiency reduces the most during this time, which detriments the economic product production.

The quality of supply: like other nutrients the quality of supply has an effect on protein utilisation also. The efficiency of utilisation reduces with the increase of the protein portion. However this fact only partly can be taken into account, since the maximum of utilisation can be only achieved with feeding with such small amount of protein, which is not possible at economical fattening. For the optimal growth we have to make compromises between the utilisation of protein and weight gain.

Protein-energy ratio: the protein content of the feed portion is also determined by the energy level of it. The higher energy intake only results in greater protein incorporation if proportionally more energy is available. Therefore, in the compilation of the feed portions the most important task is to ensure the protein-energy ratio of the feed.

3. 6.3. THE NUTRIENT REQUIREMENTS OF MILK PRODUCTIONDue to the conscious breeding work of man the milk production of cattle, sheep, goat nowadays are not only enough to rearing their offspring, but it also plays an important role in human nutrition (Jauen, 1985; Haenlein, 2004).

Basically it can be said that the animals produce the nutrients of the milk with a very good efficiency. In terms of energy efficiency the milk production immediately follows the life sustaining processes, ahead of all animal product productions’ energy efficiency. The further preferred feature of the animals is that the good transformational efficiency can be produced with feeds which have high fibre content, and cannot be used in other areas.

3.1. 6.3.1. The energy requirement of milk productionThe energy need for milk production is determined by the amount and composition of the produced milk. Outside these we also have to know that how efficient the animal utilises the energy taken in by the feed, which is basically depend on the species of the animal. The species also determines the inner content parameters of the milk. Among the economically important farm animals the milk of the rabbit has the highest energy content, which is close to 9MJ/kg. The next one is the energy content of the milk of pig (5MJ/kg), this id followed by the milk of the sheep (4,9MJ/kg), while the milk of the cow, which is consumed in the largest amount, only has an energy content of 3,1MJ/kg (Robinson, 1990). The horse has the least concentrated milk, which contains 2MJ/kg. It is an interesting note that the cow is able to utilise the energy from body weight loss for milk production.

3.2. 6.3.2. Protein requirement of milk productionWhen determining the protein requirement of milk production, we have to consider the amount of protein excreted with milk and the degree of the protein utilisation. For milk production this is about 50%. All of this information held, usually we calculate that the feed must provide for the animals 2.5-2.7 times more protein than it is excreted with milk (Forbes, 2007).

Addition to the energy and protein, we have to provide calcium and phosphorous for the dairy animals, since with every litre of milk 1.28g Ca and 0.95g P are emptied.



4. 6.4. NUTRIENT REQUIREMENTS OF WOOL PRODUCTIONThe wool grows steadily all year around, but in the winter month the growing of the wool fibres are less intensive (at continental weather conditions). This is due to two factors. First of all, usually the feed supply is worse at winter, secondly in cold environment the blood supply of the skin is worse which impedes the growth of the wool. The feeding of the sheep affects both the quantity and the quality of the wool. The energy poverty and more especially the lack of protein decrease the diameter and the length of the wool fibres.

On the basis that the growth of the wool is continuous the energy and protein requirements of the wool production cannot be accurately determined. An order or less is the magnitude of the energy and protein utilisation efficiency than the nutrient indicator of efficiency of maintenance. There are many recommendations for energy, but in every case the energy requirement for wool production is counted in the maintenance energy. This amount ranges between 6-15% of the life maintenance energy.

The biological value of the protein used for life sustaining is 70%, almost the double of the biological value of the protein used for wool production (barely 40%). This fact is related with that the amino acid set of the feed and the microbes do not match with the amino acid composition of the wool. The most striking difference can be observed with sulphur-containing amino acids (Reis and Schinckel, 1963.; Reis, 1967.; Langlands, 1970). The first limiting amino acid of microbial protein is metionin, which contains sulphur and can transform into cystine at any time which is essential for keratin structure. The cystine content of keratin varies between 9-12% depending on age and breed, which means 3-4% sulphur content. If the sulphur content of the wool decreases below 3% indicates that there is not enough sulphur containing amino acid for keratin synthesis.

5. 6.5. THE NUTRIENT REQUIREMENTS OF EGG PRODUCTIONWe talk about most common the egg production of hen, since the vast majority of table eggs are produced by hen. Prior the domestication the egg production of hen was only for the propagation of its species but due to the breeding work of man today the egg production of domestic fowl is many several times the amount of eggs needed for species propagation (300 unites/year).

5.1. 6.5.1. The energy requirement of egg productionTo determine the energy requirement of egg production we have to know the size, the composition of egg and the energy efficiency of egg production. The energy content of an average size egg (60g) is approximately 400kJ. Results of various experiments have shown that during egg production the energy transformation efficiency is around 60%, so to produce a piece of egg 670kJ metabolizable energy is needed for the hen. The relatively low 60% energy transformation is due to that the construction of egg shell also requires significant energy input, while calculating the energy efficiency of transformation, we only take into account the energy incorporating with organic compounds. When the egg production begins, the hens did not achieve their full body size, so with ad libitum feeding their nutrient uptake is greater than it is required for egg production. This luxury consumption maintains even after the animals are fully developed. This can lead to such level of obesity which may reduce the egg production. To avoid this, when the full development is reached, it is necessary to reduce the energy content of the feed with 6-8%. This does not affect the egg production, but slightly reduces the weight of the eggs.

5.2. 6.5.2. The protein requirements of egg productionThe protein requirement of egg production is determined by the level of production, the digestibility and the biological value of the fed protein. The 60% of the protein need of the animal is for egg production. Maintenance requires 30% while body weight gain needs 10%. In layer feeds usually the sulphur content amino acids (metionin, cystine) and lysine limit the utilisation of protein. If the protein requirement of hen is not covered by the feed the hens are able to compensate for a certain level with surplus feed intake (Hurwitz and Borstein, 1973). As the time of egg production is not evenly distributed, it was suggested earlier that in parallel with the decrease of production the amount of protein in the feed have to be also reduced (multi-phase feeding). Nowadays the same amount of protein is provided for the animals throughout the whole production period,



since the system takes into account that the animal gets exhausted, and due to this the utilisation of protein impaired.

In addition to the protein and energy need the mineral needs are also a priority in egg production. An egg of a hen contains 1.8-2.0g Ca and 0.11g P. An average sized laying hen depletes four times its P content, and thirty times it’s Ca-content during an annual production of 300 pieces of eggs. These values demonstrate well the importance of the mineral need and particularly the good lime supply of laying hens (Atteh and Leeson, 1983).

The shell of the egg is formed over a period of 13-14 hours, and for this 120-130mg/hour calcium has to be excreted. For this the total Ca-content of the body has to be replaced six times. As usually the lay of the eggs happen in morning, the excretion of lime has to happen during night, but this period does not coincide with Ca absorption, so the organism has to compensate temporary from different stores of it. The stores are in the Ca content of long bones, flat bones, spinal vertebrae and the surface of the spongiosa. The reserves of the hen are sufficient for production of the shell of 4-5 eggs. After the depletion of the reserves hormonally shuts down the ovarian function so the egg production stops (McDowell, 2003).

6. Test questions:1. What kinds of factors are influenced the maintenance energy?

2. What kinds of factors are influenced the protein requirements of weight gain?

3. Why the mineral elements are so important in the feeding of layers?

4. What are the roles of the sulphur-containing amino acids in the wool production?

7. Recommended readingBabinszky, L., Halas, V., Verstegen, M.W.A. 2011. Impacts of climate change on animal production and quality of animal food products In: Blanco, J. A. and Kheradmand, H. (Eds): Climate Change, Socioeconomic Effects. In Tech Open Access Publisher. 165-190.

Fekete, S. Gy. (Ed). (2008). Veterinary Nutrition and Dietetics. Foundation for the Hungarian Veterinary Science. Budapest, Hungary.

McDonald, P., Greenhalgh, J.F.D., Morgan, C.A., Edwards, R., Sinclair, L., Wilkinson, R. (Eds). 2011. Animal Nutrition. Seventh edition. Pearson Education, Limited. Harlow, UK.

Nutrient Requirements of poultry. 1994. National Research Council (NRC). The National Academies Press, Washington, D.C. USA

Nutrient Requirements. of beef cattle. 2000. National Research Council (NRC). The National Academies Press, Washington, D.C. USA

Nutrient Requirements of dairy cattle. 2001. National Research Council (NRC). The National Academies Press, Washington, D.C. USA

Nutrient Requirements. of small ruminants. 2007. (sheep, goats, cervids, and new world camelids) Animal nutrition series. National Research Council (NRC). The National Academies Press, Washington, D.C. USA


Pond, W. G., Church, D. C., Pond, K. R., Schoknecht, P. A. (Eds). 2005. Basic Animal Nutrition and Feeding.



8. fejezet - 7. FEED CONSERVATIONIn order to provide the market with animal products all over the year, the continuity of production is essential. The one of the most, maybe the most important factor is the feeding. To ensure the continuous production it was necessary to have the right quantity and quality available throughout the year. This is not a problem is certain climatic conditions (in tropics, or in cases of mild wet winters), but in continental climates during winter it causes a serious problem (Miller, 1979). In order to continue the production, it was indispensable to preserve the feed.

If we are talking about feeds, we can classify them in various ways. One of these options is that if the feed is animal or plant originated. Usually if we speak about feed preservation, we think about the preservation of plant originated feeds, but in many cases we also have to treat the animal originated feeds as well in order to maintain the appropriate quality.

In the case of plant originated feeds the preservation is necessary for two reasons. The first is the plant cell respiration. The plant cells respire even after the harvest. Due to this, the cells oxidising carbohydrates, which reduces the carbohydrate content of the plant, thus energy content of the feed. Nutrient loss from cell respiration can achieve high amounts. As it has been already named, in this case we speak about cell respiration, and respiratory itself requires the presence of oxygen, so if we can develop an environment where is no oxygen, we can overcome one of the nutrient lowering factor.

The other major problem, which we have to face, is the bacterial life which surrounds us. On the plant, which is used as feed, countless amounts and species bacteria are living. After the plant is harvested, these bacteria are continuing to live and multiply, and the nutrients needed for their life processes are lured away from the plant, thus reducing its nutrient content. In order to stop this process, it is necessary to develop an environment where the bacteria are unable to live and reproduce.

The practice has three different solutions to eliminate these two problems:

• Drying: Reducing the moisture of the feed such low levels where both cellular respiration and bacterial living is stopped.

• Fermentation: Crowding out the air of carbohydrate-rich, succulent feeds, which have to be stored in such way so that the lactic acid bacteria in them are multiplying rapidly and in great extent; in the shortest possible time to produce lactic acid as much as possible, thereby to create a favourable low pH, which shuts down the bacterial life.

• Cooling: providing a temperature, where the life processes of bacteria are drastically slowed down, so that the feed, which we would like to preserve, keeps its quality for a long time.

As the third practical solution, the cooling is widespread among human nutrition (thinking about the refrigerator, or the freezer), feeding is preferring drying and silage making.

1. 7.1. FEED CONSERVATION WITH DRYINGThe drying is the oldest method the preserve feed. Actually, it only requires sunlight, and therefore it has a very little technological demand. The drying can be used for preservation of forage and feed grains, but in case of modern feed preservation it is very important to separate the applied procedures in case the of the two different groups.

1.1. 7.1.1. Drying foragesAfter drying the green roughage, the preserved feed is called hay. The hay is the version of the green forage’s parts above the ground, which contains the both the vegetative (stem, leaf) and reproductive (flowers) parts as well. During drying, from the perishable green roughage, we obtain feed type which can be long stored, because the freshly mowed roughage’s 75-85% moisture content is reduced under 20%.


7. FEED CONSERVATION

We can categorize in many ways the hays of different plants. One possible categorization can be done on the basis is that the hay itself is what type of plant or plants if formed. Distinguishing in botanical composition base:

• grasses (by inner content and yields we can differentiate: I. II. and III. order grasses)

• legumes (Leguminosae)

• the hay mixture from the two above

1.2. 7.1.2. Factors affecting the quality of haysOf course, in order to use the most effectively the variety of hays during feeding, we have to be aware the intrinsic value of the hays and with that different factors how affect on it. During production, harvest and storage a number of factors can affect on the nutrient value of the hays (Lassitier and Hardy, 1982).

• location of the production area: alone the place of the plant production itself can determine the intrinsic values, the facing of the area, how much sunshine does it get, what are the soil conditions (soil type, nutrient supply), what kind of water supply does the area have, all of these parameters have a serious impact on the nutritional quality of the feed.

• botanical composition of the vegetation: obviously the simplest affecting factor is that what kind of species are involved. If we produce legumes, the feed’s protein content will be larger than in the hay which composed by grasses. It is also important that the given plant species what kind of foliage and stem relative ratio have. If the foliage is more and the stem is less, the hay’s fibre content is lower (thin stems, small nodes).

• time of the harvest: with the progress of vegetation period, the intrinsic parameters are continuously changing. This change varies in different plants, but generally speaking with the progress of time the protein content of plants is decreasing, and the fibre content is increasing. When we choose the harvest time, we not only take into consideration the intrinsic values, but the yields as well, because as the growing season progresses, the yield is per hectare is increasing for a while with the evolving and growing of the plants. The problem is that the increasing of quantity is inversely proportional with the quality changes. So the people have to make a compromise. The question is that where the point is where the yield is sufficient and the quality is good. This assessment may depend on many factors.

• weather: the weather, as a factor, in many cases have an influence on the hay’s quality. First of all, the weather during the growing-season determines the quality of the hay, and the loss resulting from the drying procedure.

• stubble height: the stubble height is basically determines the hay’s fibre content, and the amount of the yields. The smaller the stubble height is, the bigger is the hay’s fiber content and the yield per hectare.

• Drying technology: the method and the duration of drying of the hay is one of the important factors which determinate the quality. If during drying process we only rely on the Sun’s energy, the weather conditions are crucial (sunshine, rain, wind). If we use another type of energy, the more rapid is the drying, so the intrinsic parameters are more favourable. Of course, it should be not overlooked that these operations are expensive, so in order to worthwhile for doing them, we need to know whether the intervention is cost effective.

• Method of storage: after we dry the forage plants we have to store them for a relatively long time (several months). The storage conditions are have be that kind the preserved feed should not suffer a quality loss.

1.3. 7.1.3. Hay making lossesDuring drying and storage periods the nutrient loss can achieve serious rates and may occur in many ways. Our goal is to minimize this nutritional loss, in order to provide the best nutritional value feed for our animals during feeding, even months after the harvest.

Respiratory loss: this loss occurs almost immediately after the slaughter of the plant, and maintains until feed’s moisture content is not reduced to approximately 35-40%. This form of loss can achieve 15-20% of the feed’s total nutrient content. Of course the rate of loss depends on moisture content during harvesting and the form the drying’s speed. The sooner we reach the desired dry matter content the less is the respiratory loss. Numbers of options are available to accelerate the drying’s speed, but these options are energy consuming, so we always



have to take account of the costs.

Leaching loss: leaching loss is occurring if the cut plants are drying. In this case plants can get wet from the ground which affects on the drying rate. Another problem is that if the drying process takes place in conditions wherein the plant is exposed to the weather, due to wet conditions the rain water can wash out nutrients from the plant, which results in nutrient loss. In addition to nutrient losses, the high moisture content could also cause the rot of the plant, which can cause quantity and quality loss. To avoid this, it is important to shorten the plant’s exposure to natural forces.

The roll off of the leaves: this type of nutrient loss mainly occurs among the legumes. The most exposed plant to rolling of the leaves is the lucerne, during the drying process it may lose the 20% of the nutritional value, which derives from the leave’s rolling off. For the lucerne plants 60% of the nutrition content is in the leaves, so the loss from the leaves’ rolling off can achieve very high value. This problem not only occurs during preservation but also during storage. The previously dried leaves are easily break and crumble, so they become inaccessible for the animals. This problem is compounded by dust-forming, which is also unfavourable for animals.

Fermentation loss during storage: this type of nutrient loss only occurs if the appropriate moisture content (12-14%) is not achieved during the drying process. In this case bacterial life is not completely shut down in the stored hay, thus the fermentation process starts owing to which the nutritional content is reduced (3-7% loss).

Carotene loss: in parallel with the harvest the plants’ carotene content immediately begins to decline. This can be trace back to two factors. One is the carotinase enzyme which is released from the plant, it starts to split the produced carotene, the other is the oxygen which also oxidises the double bounds of the carotenes. This can be drastically reduced with wide variety of feed conservation and feed treatment techniques.

Decreasing of digestibility: in this case we do not talk about specific nutrient loss, but rather the decrease of the nutrients’ digestibility or utilization. This may include the caramelisation of sugars due to thermal effects, or the denaturation of proteins. Both cases are leading to decreased intrinsic value.

1.4. 7.1.4. The technology of hay makingWe can divide the hay making into 2 big groups depending on what kind of energy we use. The first group is when we only use solar power for drying. This method is a centuries-old, or an even longer millennia-old tradition (Church and Pond, 1988). In this drying method we do not use any other energy source, so the cost of the drying is relatively low. The drying can occur in order or on scaffolding. In the other group, additional to solar energy (or maybe without using solar energy) we use an another energy source and we dry the forage artificially. Mostly we use airflow which can be cold or hot air.

1.5. 7.1.5. Traditional order drying with the help of solar energyThis is the most ancient way of hay making. We scythe the plant and we would like to preserve, so we dry it with the help of the sun by leaving it on the growing area until the hay’s moisture content does not reach the right level (14%-18%). Then we gather the hay and store it in some way.

One of the biggest disadvantage of this technology is that the process is very exposed to the weather. If the weather is too cold or wet the hay can lose a lot of nutrients and it is possible that it starts to rot, because the lot of water. The nutrient loss can even reach 40%-70%. In order to properly dry the cut plant we need to rotate it. Long ago rotation was done manually, but nowadays we can use a lot of machinery (windrowers), like we can use a lot of machinery for cutting the plants (Schytes, Conditioners). It is a fact that the forage dries on the growing area and we need to rotate it frequently for the proper level of drying results in that this technology is labour-intensive either by using manual or machinary labour. This highly increases the cost of preservation. Formerly the roughage was collected and stored in stacks, but nowadays the roughage is stored mostly in various sized and dimensioned bales. Bales can be distinguished into two kinds of bale types. Square bales and round bales. The square bales are mostly small while the round bales are mostly big, and can even weight 600-700kg. The balers can be distinguished into 2 big groups.

Fix chamber balers:

• The compression of the bale starts on the outer part and goes inwards (Roll balers) (Figure 28).

• These kind of bales’ centers are loose, they ventilate easily, so the bale can be easily dried afterwards



• Primarily leguminous and higher protein contained herbs are baled with this kind of machines

8.1. ábra - Figure 28. Fix chamber baler

Variable chamber balers:

• First the center of the bale is made and then the compression goes outwards (drifted baler) (Figure 29).

• These bales’ centers are solid and they can’t be dried afterwards

• Mostly hays and straw bales are made with this kind of machines.

8.2. ábra - Figure 29. Variable chamber baler

Rack drying methods

The rack drying methods are usually used in high moisture or in colder, mountain areas. The cause of this is that in these areas the weather is colder, the grounds’ moisture level is higher, so the forage is not drying properly and there is the possibility of remoisturing from the soil. To avoid this the simplest method is that if we pick up the forage, which we would like to dry of the ground, and dry it on a good ventilated scaffolding, where the air can flow through it and we don’t need to be concerned about remoisturing. All of the scaffolding methods are labour-intensive because they can not be mechanized. This fact limits the usability of these methods, since in industrial circumstances they are hardly usable. Basically we distinguish 3 different rack types:

Finnish broach: The skewered drying method is when we place the forage on a 3-4 meters tall skewer. The advantage of this method is that it needs small area, but we need to place a lot of skewers (300-400 pcs/ha) if we would like to dry and store the forage this way. It is a proper drying method for leguminous plants and grasses (Picture 3). The drying time is 10-14 days depending on the weather.

8.3. ábra - Picture 3. Finnish broaches



Swedish rack: It needs a more complex rack system than the Finnish broach, but since the forage is not so tight in the rack; the drying time is shorter (7-10 days). We can even shorten this time if we cover the rack with a small cap (Picture 4), which prevents the forage to get direct contact with moisture. We need to be cautious that the forage does not get into contact with the soil, so it does not absorb water from the ground.

8.4. ábra - Picture 4. Swedish rack

Hay dryer pyramid: while with the other 2 method the drying can be made in various different places, the hay dryer pyramids are usually placed on meadows (Picture 5). This results in smaller drying cost, but since the drying happens on the growing area it slows down the growth of the next generation and lowers the yield of the area. To reduce this effect the pyramids are equipped with skids so they become movable. The pyramid has hollow in the center (frame), thanks to this the wind can blow through it, which accelerates the drying process.

8.5. ábra - Picture 5. Hay dryer pyramid

1.6. 7.1.6. Drying with air-flowThe previously mentioned technologies are just using only solar energy to conserve the feed. Of course nowadays there are many other methods are available with which we can produce feed more quickly, in larger quantities and in better quality. Most common air is streamed so the water loss of feed is more quickly, which is favourable for us. The streamed air can be warm as well as cold. In both cases, we can count with several advantages, which is not depending on whether we use cold air or warm.

The technology is independent of the weather conditions: With using only solar energy, we are often exposed to weather. If it is cold and it is raining, the air’s humidity is high, the drying process slows down, and even stops, and if a major rainfall occurs, the feed may take up water.

Nutrient loss: The direct consequence of slow drying process is that the nutrient loss is increasing. In extreme cases the high moisture content can induce the feed’s rot which could mean the total amount’s loss.

Reduction of the risk of warm up (auto-flammability): The cut plant cells do not die immediately. If oxygen is available they continue to respire and operate, for which the required energy is provided from the plant’s carbohydrate content. This results in a reduction of the plant’s nutrient content. During the cells’ respiration the carbohydrates are degraded to water and sugars, while heat is generated. This generated heat can achieve and such a high degree that it can lead to auto-flammability if the drying process drags on. With air streaming drying



the drying is much faster, so this problem can be avoided.

Faster harvest: Since the plants are not drying in the fields, the young plants can grow earlier. This results in a higher yield for the entire culture period. We can find different solutions among air streaming drying processes. There is a possibility to dry the whole and the chaffed plants. When drying the whole plant, there is a possibility to drying the stack and separate bale as well. In case of stack drying in order to improve the efficiency of drying a scaffolding is used, the plants, which will be dried, should not be dried simultaneously, but intermittently (Figure 30).

8.6. ábra - Figure 30. Special rack for air-flow drying

The chaffed forage’s drying process is much simpler, since due to the smaller size and larger surface, the drying is much faster and more efficient. In this case different types of drying tower are used (also suitable for drying grains), which produces quickly and really good quality product.

1.7. 7.1.7. Cereal Grain dryingOne of the most important area of feed conservation is the drying of cereal grains. As in continental climate plants only yield once a year, but their use as feed is continuous, it is very important to safely store the grain for feed. At harvest the grains have a much higher water content (25-30%) than we could store them safely (12-14%).

The drying starts with the crop’s cleaning. It is very important to have the same size and density of crop pieces entering to the drying process, because the amount of heat is constant during drying. In case of a smaller or less dense material (stem, leaf), it may occur that it is over dries, and even catches flame. The presence of stem and leaf not only cause problem during drying but also during storage. These materials remoisture more easily and may mildew which can spread to the core as well. The presence of broken seeds can cause quality problems, because in this case various oxidation processes take place more quickly which results in nutrient loss and hydrogen peroxide formation.

After cleaning, drying itself is coming. The technology is very expensive procedure. Currently, approximately 4-5€ per metric tonnes should be counted for it. The most common cereal grains for feed are dried in special drying towers. Theoretically, the drying tower can be divided into 3 parts. The drying happens in the uppermost and in the middle part, whereas in the lowest zone only cooling is proceeds (Figure 31).

8.7. ábra - Figure 31. The ways of the air in a tower dryer



The drying in the top two zones is called two-staged drying process. The drying air’s temperature, which is used here, varies between 80-130°C. In the past, the drying was carried out only in one stage, but this had several disadvantages, which was solved by the two-staged technology. One major problem is that the one-stage drying process’s energy need is 25-35% less, so the two-staged method is cheaper. The lower operating costs are also advocated by that the air with lower water content in the lower stages is reused by that it is redirected to the upper feed with higher water content, so the heated air is repeatedly reutilised. Another problem is that in case of single water content reduce, within the core the pressure can have big differences, which can lead to the rupture of the core. If the core ruptures, it can cause a number of problems. This could be the opportunity of microbial infection, or the oxidation of several useful nutrients.

Test questions:

1. Describe the different rack drying methods

2. What kinds of factors influence the nutrient values of the hay?

3. What is the point of the two staged drying technology of the cereal seeds?

4. What are the differences between the operation of fix chamber and the variable chamber balers?

2. 7.2. FEED CONSERVATION BY FERMENTATIONFeed conservation by fermentation is not as ancient method as drying but it is very old also. Silage making is probably more than 3000 years old. The ancient Egyptians and Greeks stored grain and whole forage crops in silos (Wilkinson and Bolsen, 2003.). As we can see the method was founded out for a thousands of years but the spreading of this technology can be tracked back for just a few hundred years, when the accidentally buried plants were dug out from the sand of the seashore, and it was noticed that the feed has peculiar odour and animals were reluctant to eat it as well. With this coincidence the silage is started to conquer the world, and nowadays it is used almost everywhere in the world for feed preservation. At the beginning only roughage was preserved with this method, but today cereal grains are also often conserved (McDonald, 1981).

Feed conservation by fermentation is also called silage making. The principle of the technology is that the carbohydrate-rich, succulent feeds are stored that way that the air is extruded and the lactic acid bacteria are multiplying rapidly and extensively; to produce more lactic acid in the possible shortest time, thereby to develop a favourable low pH. If sufficiently low pH occurs in the feed, the bacterial life stops and thereby we get a preserved feed. Our goal is to run out of oxygen as soon as possible in the silo space and to reduce the pH level in such low level in which the bacteria are unable to live (Wolford, 1984).

This feed conservation method has rapidly spread all over the world, and this could be tracked back for many factors.

• It has less loss than drying, because there are no leaves falling

• The technology is independent from the weather, so the cooler and wetter weather conditions are not affecting the feed’s quality and inner value.



• The method is excellent for mechanisation, thus the personal costs of preservation is reduced

• The lactic acid which is needed for the preservation and is produced by lactic acid bacteria has its own energy content that can be used by the animal as an energy source.

• As the feed’s exposure to sunlight is a very short period of time, the carotene can be saved.

• Due to the special flavour of the produced lactic acid less palatable plants can be also used for animal feeding, which results in a more efficient feed management.

• Some plants, which are available in hugh amount (maize, sorghum, sunflower), cannot be used because their stem is thick and it is not economical to make hay.

• Compared to hay the silage has much higher moisture content (60-65%), and as a consequence the feed is fire resistant.

• With silage feed can be stored for several years, because if we do not open the silo space the preferred conditions may persist for years. This means a safer and a more balanced feed management.

2.1. 7.2.1 Main microbial groups of ensilageOn the plant several different bacterial species can be found at the same time, which can be classified from the feed preservation’s point of view.

Lactic acid bacteria: they formed the most important group. The species in this group can be found in large quantities on the surface of the plants. Their shape can be spherical and rodlike, and they are able operate between 10-45°C. They are facultative anaerobes, which mean they are able to work in oxygen-free environment. The species in this group are basically producing lactic acid, but there are also species which also produce organic materials (acid, alcohol, carbon dioxide) in addition to lactic acid. Depending on this we can distinguish homofermentative and heterofermentative bacteria.

Aerobic spore forming bacteria: As it is in its name these bacteria require oxygen to multiply, so if the silage is proper, they cannot be found in the feed. They are most often getting into the silo by pollution with soil. Basically they are proteolytic bacteria, and they are generating highly resistant spores, from which they can reproduce rather quickly after opening the silo.

Coli aero genes bacteria: Primarily they are producing acetic acid, which is a less strong acid compared to lactic acid, so the silage’s point of view their presence is only beneficial in the early stage of process. When the pH of the feed reaches the range between 4,5-5,5 the Coli aero genes bacteria stop their operations. Their temperature range is as the same as the lactic acid bacteria’s.

Anaerobic spore forming bacteria: These bacteria are able to decompose a wide variety of carbohydrates and proteins. During carbohydrate breakdown they are competitors of lactic acid bacteria, while during protein breakdown they produce butyric acid from different amino acids. These bacteria are not only able to convert plant originated carbohydrates but they are also able to decompose the already produced lactic acid if this occurs in great quantity, it leads to the rapid increase of pH, which deteriorates the storability of the feed.

Putrefactive bacteria: These bacteria are only able to operate if the pH value is above 5.5, which is usually not a problem in case of a well made silo. If the compression is inadequate or if the pH is not decreasing quickly enough, then due to beginning of the butyric acid fermentation they can proliferate quickly and the formation of ammonia and variety of toxic substances make the feed inedible.

Yeasts: As the name implies, we are not talk about bacteria, but to preserve the quality of the feed, the different kinds of funguses are also important. One such group is the group of yeast. Oxygen is essential for their reproduction. In practice they are usually proliferate if the silo space is opened. The yeasts convert the lactic acid to carbohydrate and alcohol, thus they reduce the energy content of the feed (Driehuis et al. 2001). By the effect of the fungi’s by-products the feed becomes fragrant and more palatable. The animals are very fond of this kind of feed.

Mould fungus: The mould funguses are very similar to yeasts, they also require oxygen, and they appear if the compression of the oxygen was not sufficient. Not only it reduces the carbohydrate content of the feed, but it



also reduces the protein content because they produce mycotoxins, so their presence in the feed is particularly harmful. The animals do not like to consume the mouldy feed.

2.2. 7.2.2. The process of fermentationThe fermentation itself is a multi-staged process and its different parts can be separated well from each other. Nowadays the fermentation is divided into 4 steps.

1. Auto oxidation (self-heating) stage: the feed plant’s cells do not die immediately after cutting, but they still continue to respire. This respiration process requires a relatively large quantity of energy, and the cells obtain this energy by the breaking down of the plant’s carbohydrate content. This respiratory process continues until the plant’s moisture content is not too low, or there is sufficient oxygen or carbohydrate. During cell respiration the sugar is decomposed to carbon dioxide and water, and during the decomposition energy is released. This energy causes the heating up of the silo. The more oxygen is in the silo space, the longer the cells continue to respire, and the more heat is generated within the silo space. In extreme cases this can lead to the auto-ignition of the feed. In order to minimize the oxygen in the silo space the compressing of the silo is a very important step (Langston et al. 1962). With good compression, in approximately 1-2 day the oxygen for cellular respiration runs out, so the nutrient loss stops. In this early stage aerobic bacteria are predominate because there is available oxygen. Among these the foremost are heterofermentative lactic acid bacteria which are basically start to produce lactic acid, acetic acid and carbon dioxide. With the depletion of oxygen, the aerobic bacteria stop to function and their role is taken over by anaerobic and facultative anaerobic bacteria strains. Since the acetic acid is less acidic than the lactic acid it is important to gradually push to the background the acetic acid production against lactic acid production 2.

2. Main stages of fermentation (production of lactic acid): as more and more lactic acid is produced the operation of those bacteria species is shut down for which the acidic environment is inadequate. This means that there is a new niche for the lactic acid producing bacteria, which means more lactic acid, and an even lower pH. It is can be seen that this is a self-reinforcing process, at the end the feed’s pH is so low that only and exclusively the lactic acid producing bacteria are able to live. Depending on the water content, at pH 3.4-4.5 even the lactic acid producing bacteria’s operation is inhibited. This stage lasts until the bacteria have enough carbohydrate to ferment, or the feed’s pH is so low that even the lactic acid producing bacteria’s operation is shut down. Ideally this process takes 2-3 days, at worst it can take 1-2 weeks.

3. The moderating stage of fermentation: in parallel with the decrease of pH, the bacteria begin to cease their operation. If the pH is sufficiently low the bacterial life completely ends. This state is called constant silage. The entire ensiling process is intended to achieve this status as soon as possible. If this is succeeded in that case we talk about preserved feed. The pH value, at which we speak about constant silage, is depending on the feed’s water content. The higher is the feed’s water content, the more lactic acid is required, and hence the lower is the pH value that we have to achieve to get stable silage (Table 34).

8.1. táblázat - Table 3. The connection between dry matter content and the pH level

Dry matter (%) pH

20 4,2

25 4,3

30 4,4

35 4,6

40 4,7

If the pH value is not reduced to that level, where bacteria completely end their operation, in that case a secondary fermentation process starts. The butyric acid degrading bacteria multiply, which produce butyric acid not only from the feed’s carbohydrate content, but they may also convert butyric acid from the already produced lactic acid. This results in the continuous increase of the pH value, with which in parallel those



bacteria reactivate which previously stopped their life functions, and this speeds up the whole process.

4. Stage of post-fermentation: after opening the silo and at the beginning of exploitation, the silo gets in contact with air. This very moment, those bacteria which require air for their vital processes and have been inactive (because there was no oxygen in the silo space), they start to operate again. First, the opened silo’s surface gets in contact with oxygen, but depending on the compaction, the oxygen enters to the silo. The better the compaction was the less able is the oxygen to enter into. And as the usage of silage as feed is continuous, it does not cause any significant problem (nutrient loss). But if the compaction was not good, than the oxygen may enter several meters deep into the silo space, where the reviving bacteria and fungi can significantly reduce the nutritional value of the feed. This process is called post-fermentation. Nowadays propionic acid treatment is used on the silage to prevent post-fermentation.

2.3. 7.2.3. Influential factors of the fermentability of feedstuffsAs it could be seen, there are several factors that can affect on the fermentation processes occurring in the feed, and these basically determine the nutritional content parameters of the feed, and the method and duration of the storage. All of these factors are important from the perspective of feed management. In order to make the fermentation more efficient and economic, let’s get familiar with the most important factors which affect on the fermentability.

Carbo-hydrate content: one of the, if not the most important factor, if we examine the fermentability of different fodder-plants. The bacteria obtain the necessary organic acids (lactic acid is the most important) form carbohydrates. However carbohydrates themselves are forming a very large group. They include fibers (cellulose, hemicelluloses), and also different kind of sugars as well. The properties of these compounds are different, and thanks to this the bacteria are not able to break down them in the same way and with the same efficiency. There are several kinds of carbohydrates which cannot be converted into lactic acid by bacteria. This group includes the carbohydrate based fiber constituents, and so does the starch. For lactic acid production the best kinds of carbohydrates are sugars. Glucose can be converted to lactic acid by any kind of bacteria, but the most species are able to convert the fructose and the sucrose as well. In order to the lactic acid lower the feed’s pH for the sufficient value, whole silage amount’s 1-3 have to be the lactic acid content. To produce this amount, there have to be enough sugars in the feed. If the plant does not contain enough sugar, then the ensiling process will not be appropriate. The fermentable sugar content of different plants is very variant. It depends on the plant species (legumes have few, but the corn and sorghum have a lot), the fallen rain amount in the growing season, the plant’s vegetation stage, and even on the time of the day at harvest. In the morning, the plant’s sugar content is lower, because the organic material produced by photosynthesis the previous day, the plant stores it in the form of starch. In the morning, when the photosynthesis starts, the organic matter transforms to sucrose in order for better transportability, increasing with this the plant’s sugar content. Thus the afternoon harvest results a better ensiling ability.

Dry matter content: from the fermentability’s point of view, the dry matter content of the plant can vary widely. Of course, it is important to note that fermentability and the economical fermentation is not the same. The plant can be fermented between 10-70%, the optimal range is much narrower (35-40%). The primary consideration at choosing the optimal dry-matter content, is the relationship between the dry-matter and the carbohydrates. The higher is the feed’s dry-matter content, the more are the fermentable carbohydrates the feed contains. This means that the increase of the dry-matter content is favorable until a certain point because:

• the carbohydrate content is increasing

• in less fluid space, the same amount of lactic acid means a higher concentration (less lactic acid is needed for preservation)

• the osmotic concentration in the cells is increasing, which prevents the multiplication of the bacteria.

Of course, the increasing of the dry-matter content is only good until a point, when this is exceeded, negative processes take place:

• all bacterial operation is inhibited, so the lactic acid producing bacteria are not able to produce enough lactic acid (the lactic acid bacteria are able to tolerate higher osmotic pressure).

• too little water content reduces the compress rate of the feed, which complicates the development of anaerobic processes.



Protein content: the feed’s protein content basically reduces the feed’s fermentability. This is caused by two factors: If the feed’s protein content is higher, the other nutrients’ content is less, the amount of easily soluble sugars are also less. This in itself is a very negative effect. Another problem is the ammonia, which is formed at the decomposition of proteins, binds a portion of the formed organic acids. It is not enough that there is already less organic acid is formed, because the sugar content is lower in the plant, but a portion of this lessen amount of acid is neutralized by the ammonia.

Fertilization – chemical fertilization: this technological step, which is related to plant production, has basically an effect on the plan’s protein content, and thorough this it modifies the fermentability. If we use a large amount of nitrogen supplementation, the feed’s protein content increases. If we are talking about pasture or meadow, we not only increase the protein content of the feed, but we also have an influence on the area’s botanical composition. We shift it in a direction where those plants are spread which can tolerate the higher nitrogen concentration, thus we reduce more the easily soluble carbohydrate content, which makes more difficult the ensiling.

Compression: the most important task of fermentation is to provide the airless (anaerobic) environment as soon as possible, by the extrusion of air from the silo space. The more air we are able to oust, the sooner we can reach the airless environment, which is a prerequisite for high quality silage. Thanks to the little oxygen, the heat generation is at low level (we don’t have to worry about auto-ignition, different nutrients are not affected).

Chaff size: two important factors have an effect on the size of the chaff. One is the compressibility (the smaller the better to be compacted), the other is the feed’s bacterial digestibility (the smaller is the chopping, the larger is the surface, which means better digestibility). Considering these factors, it would be best, if we simply grind the feed. However in general with the silage we feed ruminant animals, where our most important task is to maintain the rumen’s function. For this it is essential the presence of the right amount structural fiber which ensures the saliva production and through this it prevents the rumens acidification, which would mean the death of the bacteria. Knowing these factors, the animal breeders are trying to chaff the feed to the minimum size, where the plant fibers still strain their structural impact (the minimum size is 0.8-1.2 cm).

Buffer capacity: the buffer capacity is an artificial term which attempts to express in a number the difficulty of different feed’s fermentability. As we could previously seen, there are several factors affecting on the fermentability of the plant either in a positive or a negative way. There are many substances in the feed which prevent the rapid decrease of silage’s pH (minerals, organic acids, ammonia). The combined amount of the substances, which make the pH reduction more difficult, is called buffering capacity. This index-number which shows that how much (g) lactic acid reduces 1kg dry-matter content’s pH value to 4.0 (Kung and Shaver, 2001).

2.4. 7.2.4. Grouping of feeds based on their fermentabilityIn terms of fermentability, the feed can be divided into three big groups. It is important to be aware the different feed types’ fermentability, because in each and every case there are different solutions are recommended in order to feed our animals with the matching quality feed.

Easily fermentable feeds: these feeds are basically characterised by that their carbohydrate content is easily soluble, and therefore without any treatment of the feed, a good quality silage can be made from them. The placing in storage process is single threaded. Waiting until the feed’s moisture content is optimal, than cutting off and chaffing them, and storing the plant for ensiling. Our most important silage plant, the silage maize belongs to this group, and so does the sorghum, different kinds of beets, and many cereal grains which can be well ensiled.

Medium fermentable feeds: these plants’ optimal nutritional and moisture content parameters are not coinciding. As the plant’s chemical composition is taken into account at harvest, the plant’s moisture content is too high at the moment of the harvest to be directly enter into storage. In order to achieve the optimal water content, the plant is parched, and it is put later (2-3days) into the silo space. It may cause a problem that these plants have a lower carbohydrate content, which can be improved with smaller amounts of different auxiliary materials (molasses, grits of cereal grains). Different kinds of grasses, rape, lupine and green grains are belong to this group.

Hardly fermentable feeds: these plants generally have high protein content, and low easily soluble carbohydrate content (legumes), and they have a high buffering capacity. A good quality fermented feed can be made from them only if they are parched and different auxiliary materials are added to them, which support the fermentation process.



2.5. 7.2.5. Nutritional loss during ensilingIn the case of ensiling we have to reckon with many factors that could cause losses just like during the drying process. Depending on the location, where the loss arises, we can distinguish field losses and silo space losses.

Field losses

Respiratory loss: this type of loss remains until the oxygen is consumed in the silo space, so we have to calculate with the respiratory loss both in the field and in the silo space. If the plant cannot be harvested with a single pass, the respiratory loss, which the plant suffers during parching, is much higher.

Leaching loss: this loss only occurs during two-pass harvest. When we speak about a single-pass harvest, the plant does not encounter with the soil, because in parallel with the harvest the plant is also chaffed. We only have to count with the leaching loss if the ensiled plant has to be parched, because in this case the plant is on production area. If the soil is too wet, or it is raining during the parching, this type is loss is inevitable.

Mechanical losses: this loss is resulting from the two-pass harvest. At single-pass harvest, the plant is cut and immediately chaffed. The mechanical loss is minimal. At two-pass harvesting, the machines have to pick up the parched plant from the ground, which cannot be made with 100% efficiency. At pickup, the 5-8% of the stock stays in the ground. This is the mechanical loss.

Losses in the silo

Respiratory loss: As it was previously mentioned before, this kind of lost is maintained until the oxygen is depleted, so we have to reckon with it both in the fields and in the silo.

Fermentation loss: It is resulted from the proliferation of bacteria and the continuous production of organic acids, because this quantity of organic acid is being produced by bacteria from the plant’s carbohydrate content, which reduces the feed’s nutrient content.

Pouring loss: Since during harvest the plant’s moisture content is high (60-65%), a silage effluent is formed due to the compression, which accumulates at the bottom of the silo space. If this leachate is not collected, the nutrients are removed with the liquid, and this means a loss.

Denaturation loss: Generally it occurs in poorly compacted silos. If too much oxygen remains in the silo space, the cell respiration stays for a long time, and heat is produced along with the breakdown of carbohydrates. If the temperature rises to high in the silo, certain nutrients may denature, which reduces the nutrient digestibility or metabolizability.

Surface loss: This loss is resulted from exploitation. Basically, we are talking about physical losses, because it is generated by the scattered feed during exploitation. Primary it occurs in pier silos. It is not typical of plastic tunnel silos and silo towers (McDonald, 1960).

Post-fermentation loss: This is a biological type of loss. This loss arises because oxygen enters into the silo space at the spilt, and the inactive bacteria become active again, and they obtain the necessary nutrients for their vital processes from the silage.

2.6. 7.2.6. Making haylageThe haylage making have many similarities with ensiling, but the technology differs in some points. The most important difference is that in case of making haylage, the moisture content is higher at harvest than it should be to make an economically preserved feed. Therefore we have to parch the fodder plants, which are entails that the harvesting process turns into two-pass. In the first pass, we cut the plant then in the second pass, after a few days of parching we collect it from the field, and after this it is transported to the silo space. This double work increases our costs and losses (both quantitative and qualitative). Often parching is not enough to safely ensiling the higher protein substances, we have to use different kind of auxiliary materials to achieve the favourable biological processes. These fermentation promoters can be classified into two major groups.

Carbohydrate addition: in this case the primary goal is to ensure adequate amount of the carbohydrates for the bacteria in order to produce enough lactic acid. For this, depending on the fermentability of the crop, there have to be an amount of carbohydrate which is 1-3% of the ensiled amount. This can be provided by wide variety of



ways. The most common carbohydrate source is molasses, which is an excellent nourishment for bacteria, easy to dose and measure because it is a liquid material (in case of medium fermentable plants 2-3%, and in case of hardly fermentable plants 5-6% is the needed quantity of molasses). Various grinded grains are also often using, which are good sources of carbohydrates, and they also increase the dry-matter content (due to the high starch content more should be used from than molasses: 10-15%).

Usage of biological preservatives: The promotion of fermentation can not only happen through providing the appropriate quantity and quality of nutrients to the bacteria. Nowadays bacteria cultures are often added to the ensiled crop, thus speeding up the natural process of preservation. Billions of bacteria are added to the feed, which produce much faster the required lactic acid for the preservation, this results in less loss and we also get a better quality feed. Most often lactic acid producing bacteria are added to the feed, but often propionic acid producing bacteria (fungicidal effect) are also added to the feed to prevent post-fermentation. A wide variety of bacteria species can be used, and are used to, but almost everyone of them have to comply with some parameters (have to be homofermentative, can ferment various types of carbohydrates, multiply rapidly, have a good acid tolerance (below pH 4), have to function in wide range of temperature, multiply even at low water activity, have to be active in anaerobic conditions. The most commonly used species is Lactobacillus plantarum (Yimin et al. 1999).

2.7. 7.2.7. Chemical preservationIn that case, when the required acid amount for preservation is not produced by bacteria, we should not speak about biological, natural preservation. If there is not enough time to wait until the bacteria produce the required amount of lactic acid, or the feed’s water content is too high, or there is not enough easily soluble carbohydrates in the feed, we may choose the chemical preservation. The aim of this process is to decrease the pH of the feed with some kind of acid; thereby we prevent the multiplication of bacteria (Wilkinson, 1986).

Addition of anti-microbial materials: when anti-microbial materials are used, the most important that we use are organic or inorganic acids. The using of inorganic acids (sulphuric acid, hydrochloric acid, and phosphoric acid) is suppressed, because they were very dangerous for both animals and humans. For animals, the feeding with inorganic acids could very easily upset the acid-base balance, thus special mineral supplements have to be used. For humans, the working with acids was dangerous. Also caused problems the corrosive effect, and because of this the silo spaces had very high depreciation costs. To avoid these problems different kinds of organic acids and their combinations were started to use. The most commonly used organic acids are formic acid and propionic acid (Higginbotham et al. 1998). The use of organic acids has no threat to the animals, and also a favourable property of these acids is that they have a nutritious value. This type of preservation is commonly used for cereal grains, and many companies are selling different products, which serve for the preservation of grains.

2.8. 7.2.8. Silo typesThe feed, which we would like to preserve, can be fermented and stored in wide range of possibilities. From the primitive pit, dug into the ground, to fully closed computer controlled silo towers, a wide variety of spaces can be used for if we would like to make silage. The type of silo can affect on many factors. This could be the quality of silage, the mechanisability of the technology, which is very important in the case of feed stored in large amounts, because it can basically determine the economical use. Depending on that the silo space has a fixed location or not, we can distinguish permanent and temporary silos.

Temporary silos

Temporary silos’ largest advance is that it has a lower establish costs than the permanent silos, and the depreciation cost does not exist. It is also an important consolidation that the placement of the silo is not permanent, so depending on where we need the feed, or where is enough space for storing the storing the feed, the location can be changed. The silage’s quality is also an important consideration, but it cannot be clearly stated that the temporary or the permanent silos made better quality silage. The most important temporary silo types are the following:

Trench and pit silos: the most private types of silos. The difference between these two types is only the shape of the whole dug into the ground. If the whole is elongated, rectangular we call it a trench silo, if the whole is square like we call it pit silo. In general, both types are not used in large-scale farms nowadays, because the exploitation of the silage is very difficult, there is a high probability of contamination with soil, and the silage’s



quality is not appropriate, since the contraction of feed is very burdensome. If this type is used for fermentation of feed it is common that the whole is lined with foil, which means a higher quality and less contamination.

Stack silos: it is also an already relegated type of silo. This type of silo is not in the ground, but it is situated on the ground, and its wall is made up by straw or hay bales. The feed, which is wanted to be fermented, is laid among the bale walls; the contraction and the storage also happen here (Picture 6).

8.8. ábra - Picture 6. Stack silo

Because of the size of silo space, the bale walls often have to be strengthened to prevent capsizing. Usually a kind of fence is made for this. In such silo space it is very difficult to create an airless environment, because on the wall of bale the air can pass through. To prevent this often, as in the case of pi silos, the silo space is lined with foil which makes easier and faster to achieve the anaerobic environment.

Plastic tunnel silos: one of the most recent type of silos and its usage rapidly spreads around the world (Picture 7). The technology can be used to preserve both the chaffed and the seed feeder. The essence of the method is that the feed, which we would like to preserve, is filled with a special foil filling machine into a very strong plastic tunnel, where a very good quality fermented feed can be made in very short time (O’Kiely and Wilson, 1991).

8.9. ábra - Picture 7. Production process of a plastic tunnel silo

The great advantage of the technology is that the amount of the stored feed can be determined exactly and a suitable size foil can be prepared for this and therefore the optimal amount of feed can be managed with.

Bale silo: it can be regarded as a type of the plastic tunnel silo. The technology is designed to the feed, which we would like to be fermented, is baled with high water content these bales are packed one by one and ensiled. Most often the plants with high protein content (legumes) are preserved with this technology, since the individual packing increases the cost highly of the preservation (Picture 8).

8.10. ábra - Picture 8. Bale silo



The thus preserved bales have an excellent quality, because the oxygen-free environment can be deploy and maintain easily, and the use of different assistant materials is easy. All kinds of bales (round, square) can be preserved with this method. The size can vary from the small 10-15kg bales to the large 6-700 kg bales.

Permanent silos

The main difference between the two types of silos is that the temporary silos are not fixed to a place while the permanent silos are fixed, so their transportation is not possible, or can be made but with very high costs. This means that such kind of silos’ construction and design requires a much greater investment and the maintenance of technical equipment requires much more money. To compensate this we get a system which is able to produce stable high quality silage and the mechanization of the system is solved and both the storage and the extraction can be carried out very efficiently. Two major groups of the permanent silos can be distinguished: bunker silo and tower silo.

Bunker silos: we are talking about silo types installed on the ground; the wall can be made of different kind of materials. The most common is concrete, which is produced in blocks, so the reduction and the augmentation of the silo space are both possible. The size of the silo is determined by the mechanization and amount of the stored feed. In bunker silos a good quality can be made with low cost, since the use of additives is very easy and also the compression can be easily performed (Figure 32).

8.11. ábra - Figure 32. Different bunker silos

Depending on the storage we can distinguish 2 sided (drive through) and 3 sided bunker silos. In the 2 sided silos the transporter vehicle goes in at one end of the silo space and empties the feed. After storage the vehicle goes out at the other end of the silo space. With this technology it not only transports the feed into the silo but also compress it. The disadvantage of this method is that it pollutes the silo space, since the vehicle brings in a huge amount of contamination (contamination with soil) with its wheels. This potential contamination is eliminated with the three-sided silo, where the transporting vehicle does not enter into the silo space, it empties the feed before the silo space and another machine takes into and contracts the feed in the silo. The work demand is higher in this method, but the quality of the compression is slightly better and the contamination with soil is smaller. From these silos special silage block cutters (Figure 33.) extract the silage and exploit it consistently with very high efficiency and preserving the quality of silage for a long time.

8.12. ábra - Figure 33. The operation of silage block cutter



Tower silos: with this silo type it is very easy to provide the oxygen-free environment, so high quality silage can be made. The tower silos are also can be made several kinds of materials as in the case of bunker silos, but most often they are made from concrete or from some kind of metal (Figure 34.). Basically two types of tower silos can be differentiated form each other, depending on where the silage is extracted. When the extraction happens in the top we speak about up unloading silos, and if it happens from the bottom, we speak about bottom unloading silos.

8.13. ábra - Figure 34. Tower silo

The place of unload is important because this often determines the material of the tower. It is typical that the bottom-unloading towers are made from metal, and the top-unloading towers are made from concrete. The reason is that in the case of the bottom-unloaded towers the feed have to slide down to the bottom, where the unloading happens. It is therefore very important the tower to has a smooth inner wall which helps the downward movement of the feed. Often happens that the wall of the silo is treated with special materials so the feed slides even better. There is also a difference in the size. The top-unloaded silos are larger than the bottom-unloading silos, as the bottom-unloading silo’s extraction device has to be able to endure the amount of the feed above it. This loadability limits the size of the silo space. The top-unloading tower does not have this kind of problem, so the size of the silo is not limited by anything. It is also a big difference between the two towers that the storage and the extraction in the bottom-unloading silos can be continuous. As the feed runs out from the tower it can be reloaded from the top, and when it reaches the bottom, the fermentation already have been eventuated. This means a better utilisation in time. In the top-unloading towers the complete emptying of the silo space has to be waited and after that the next dose of feed can be stored.

3. Test questions:1. What is the principle of the fermentation?

2. What are the most important bacteria during the process of fermentation?

3. What kinds of factors can be influenced the fermentation?

4. What are the differences between the silage making and the haylage making?

5. What kinds of temporary silos do you know?



4. Recommended readingMcDonald, P., Edwards, R.A., Greenhalgh, J.F.D., Morgan, C.A., Sinclair, L.A., Wilkinson, R.G. 2011. Animal nutrition. Seventh edition. Pearson Education, Limited. Harlow, UK.

Pond, W.G., Church, D.C., Pond, K.R., Schoknecht, P.A. (Eds). 2005. Basic Animal Nutrition and Feeding. Published by John Wiley & Sons Inc.


9. fejezet - 8. FEED PROCESSINGNowadays the practice uses several kinds of feeds. There are many factors that affect on which feed does the breeder prefers, but overall it can be said that the breeders hardly feed the feeds without any treatment. Perhaps the only exception is grazing, because in this case the animals go out to the pasture and take in the needed nourishment without human intervention. If the grass is moved, dried or baled, several kinds of treatment methods are used, even if they are very simple ones. The reason is for using several kind of treatment possesses is that feeds can be rarely used without any treatment. Depending on what kind of feed we are talking about, or what the purpose of the production is, or what kind of species is fed with the feed or even how old is the animal, the preparation of the feed-making has countless goals:

Size change: the most common treatment for grains with the aim of forming the different feeds into the same size, which allows producing a homogenous feed mixture. This treatment method is also used on fodders (e.g. chaffing), which helps to prevent the animals’ selection, this way non-toxic feeds can be feed, which are otherwise would not be eaten by animals with fastidious taste. This results in a more economical feeding. The chaffing may be important for silage which helps the feed contraction, thus providing a better silage quality.

Conservation: one of the most important of the feed treatment methods, with the use of it we can provide feed for our animals continuously for a long time (drying, ensiling and cooling).

Separation of some parts (fractionation): fractionation is commonly used for seeds. Often in order to avail the main products, which are important for the humans, in great amounts and purely (oil extraction – oil industry; bran, degermination – milling industry; starch – alcohol industry). Due to the fractionation animal husbandry gets large quantities of agricultural by-products.

Increasing palability (feed intake): just like humans, certain animal species (pigs, cattle, horses) prefer the feed which is tastier, and eats more from it, and the higher feed intake can lead to better production parameter.

Increasing the digestibility: in recent times, one of the most developing areas is the improvement of the digestibility of nutrients. The feed intake of the animals is limited. They simply cannot take in more than a certain amount. To increase the performance instead of increasing the amount, we have to find another way and this is the improvement of nutrient utilisation. In one unit of eaten feed is not utilised by the animal with 50% but 75%, it results in an improvement of the production. Numerous of nutrients’ improvement can be helped, but the practical animal nutrition improved the digestibility of starch, the most important energy source. Many feed treatment techniques are developed for this purpose (extrusion, expansion), which are uses both in animal husbandry and human nutrition.

Inactivation of anti-nutritive matters, detoxification: many of the animal feeding stuffs cannot be given directly to the animals, because they contain matters that are toxic or deteriorates other nutrients digestibility. They should be treated in order to use them in animal nutrition. For this we can use several kinds of detoxifying or inactivating procedure the end of which the feed can be used. One of the most common methods is the inactivation of the soybean’s trypsin inhibitor.

This operation is performed with each and probably every kilograms of soybean which will be fed all over the world.

Adequacy with feed allocation: to have a cost-effective management of feeds not only being influenced by the types of the feed but also that how great is the energy usage with which we dispatch it to the animals. To have the cheapest moving and the dose out of the feed often we have to make the feed into a state which meets the conditions of feed allocation (in the case of wet feeding of the pigs).

In order to use the feed the most optimal way we can provide number of changes. These can be physical changes (grinding), and chemical changes (the use of acids), microbiological changes (fermentation), heat treatment (cooking) and the combinations of these processes. Depending on we talk about bulk feed or nutritive mixture the different feed procedures may be separated from each other, although it can happen that one can be use for both feed groups. In the following we will examine the most common treatment procedures for forages and nutritive mixtures.


8. FEED PROCESSING

1. 8.1. TREATMENT OF FORAGESThe treatments of forages have two major groups. At the high fibre content feeds the main objective is to chopping it to the optimal size which makes suitable it for portioning, or to carry out other feed treatment methods. The other large group is the high water content fodder roots (tuberous), where the primary goal is to make mouthfuls and to promote the mixability.

1.1. 8.1.1. SlicingIt is a common used treatment method for root and tuber fodders. Due to the slicing, the feed can be easier to chew and the corresponding size also contributes in forming mouthful. Although we can feed different animals with this kind of feeds but slicing has the greatest importance for change the digestibility.

1.2. 8.1.2. PureeingWe use pureeing, just like slicing, for root and tuber fodders, but this method also can be successfully used with high water content roughage and in case of some animal origin feeding stuffs. With this method the high water content feeds can be crused better. Usually it is used in swine nutrition where it improves the digestibility of the feed (more efficient fibre digestion). Such feed can be more mixed with forages giving a more homogenous feed and this allows the mechanization of portioning. The pureeing is increasing the feed intake and thus positively affect on the performance of the animal.

1.3. 8.1.3. ChaffingChaffing is the most common used forage treatment method which is mainly used for roughage. The method can be used on large industrial scales. One of its biggest advantage is that it increases the feed intake thereby improves the efficiency of generating animal production. Due to chaffing the absorption by animals is decreased since the animals cannot get out those species that they prefer from the roughage chaffed into small pieces. This improves the feed management, since due to chaffing those feed can be fed with the animals which would be reluctant to consume in themselves. Of course this way only the less palatable feeds can be used, those are not which are harmful for the health of the animals. The other great advantage of chaffing against roughage is that the spilled loss is much smaller therefore the feeding is more economic. The chaffing eases the transport, storage, conservation and portion of the feed, which also has a significant advance, but in itself it does not affect on the digestibility of the feed. The most important key factor is the size of the chaff. Since we are talking about high fiber content feeds the primary users of the chaffed feed are the ruminants. In the case of ruminants, the precondition of the healthy digest is the normal operation of the rumen (Wallace et al, 1989.). As in the rumen the degradation of the nutrients is carried out by bacteria, thus it is very important that the pH of the rumen must be in the optimal range of 6.4-7.6 for the operation of the bacteria (Yang et al, 2001). Since the bacteria can make 5-6kg of organic acid daily, the maintain of the neutral pH is a very challenging task for the animal. This is helped by the production of slightly alkaline saliva, which may be daily 150-160L for cattle (Bailey and Balch, 1961). However the saliva production is determined by the structural fiber content of the feed. The structural effect means that the percentage of fiber content in itself is not sufficient for to produce the effect. The fiber has to have the appropriate size to trigger the production of saliva. According to current knowledge the minimal chaff size is 0.5-1.0cm, the chaff which is smaller than this cannot the produce the structural effect thus it cannot be applied effectively in the feeding of ruminants (Han et al, 2006). Chaffing is often prerequisite of other feed treatment methods so it is also often used when the primary purpose is not the direct feeding of a feed but to improve the mixability, the compliance for dispensation or the increase of density.

1.4. 8.1.4. CuringCuring as feed treatment method is known for a very long time but nowadays it cannot be really fit into the large scale intensive technology of animal husbandry so its use is almost completely suppressed. Its essence is that the less tasty, inexpensive rich are fiber but not harmful feeds are chaffed and layered with succulent raw materials (molasses, pomace, beet slice). Thanks to the treatment the fibres are softening, the lactic fermentation begins, which makes the feed palatable and becomes easier to digest. It is also an advantage that the high moisture content raw materials can be utilized better. Curing time is dependent on temperature. In summer warm weather conditions it is 10-12 hours, while it can take 1-1.5 days at winter. With this method the feed intake can be increased since the feeding is more economical.


8. FEED PROCESSING

1.5. 8.1.5. GrindingAlthough grinding is primarily used for seeds, it is commonly used with roughage as well. The primary products are hay and straw meal which are digested with different effectiveness by different animal species. We need to be aware with that due to grinding the fibre content of the feed does not change but the digestibility is improving. This is due to the cell wall effect. Since each and every plant cell is encased by cell wall contents, which are indigestible for animals, so the cell content is not available for the animal. As a result of grinding, the cell walls are broken, and the cell content is released and despite this the effectiveness of fiber digestion will not be better, but the overall digestibility of the feed improves. This is particularly important in swine farming. In swine nutrition the grinding of the feed has a positive effect; the opposite is true in case of ruminants. Due to grinding, the fiber losts its structural effect so the rumen fermentation moves unfavourably direction. The digestibility of the feed is also worse, because, of grinding the feed stays for a shorter time in the rumen, so there is also less time for the bacteria to digest the feeds. In some cases the lower digestibility is used in order to reduce the concentration of the feed, so the animal gets less energy (the finishing phase of swine fattening).

1.6. 8.1.6. Pelletization, granulationThe prerequisite of the granulation of roughage is the grinding of the feed. The granulation has several advantages. Due to this we can increase the density of the feed, which makes the volume decrease and this improves the portability and the storability as well. In addition during granulation we can enrich the feed with a number of different additives (vitamins, minerals) resulting in more favourable nutritional parameters. The granules size is determined by the particular species and age groups, but typically the diameter is 15-25mm and the length is 30-50mm (Hanrahan, 1984).

1.7. 8.1.7. BriquettingThe technology was developed in North America in the ‘70s and consequently to the present day it is still the most prevalent there. The technology itself is expensive therefore only high-producing farms (cattle, horse) can use it economically. The method is that they are combining it with the advantages of pelleting while keeping the structural effect of fiber. The basis of the feedstuff is also chaffed roughage but it does not contain only vitamin and mineral supplements it also often contains grinds of grains and thereby increasing the energy content of the feed (Virtanen, 1966). The shape varies. It may be rectangular or cylindrical in shape and the size is much larger than the pellet’s (diameter 60-80mm and thickness 15-25mm).

1.8. 8.1.8. The digestion of strawThe basic objective of this method is the better fiber utilisation of ruminants. As time progresses the plant parts begin to age and parallel with this the lignin content of the feed increases. The lignin is an encrusting material and it is responsible for when the cells become secondary woody. In young plants it only appears in 2-3%, in older plant it can achieve even 15%. These lignin molecules bind into the cellulose chain by connecting to the glucose molecules which are building up the cellulose. These binds are cannot be broken even by bacteria. Therefore the increase of lignin content impairs the bacterial digestion of cellulose. During the digestion of straw the lignin-glucose binds are torn up by different materials, which increase the digestibility of fiber by 35-40%. This means 25-30% higher energy content. It is primary used mainly in those areas and regions where the plant production is less or the growing season is shorter. This primary means the Northern region of Europe, where this is a widespread treatment method and a fully developed mechanization supports it. Many different materials can be used for digesting. Most often it is done with lye (NaOH). The NaOH solution is used in 2 concentrations (Jackson, 1977).

Wet digestion: this method uses a solution of 10-15% for the 50-100% amount of the straw which will be digested.

Dry digestion: in this case the solution is more concentrated (25-30%) and a smaller amount (1.5-3%) is used from it.

Ammonia, hydrogen peroxide, steam and different specific bacteria are also used for digesting the straw.

2. 8.2. THE TREATMENT OF SEEDS


8. FEED PROCESSING

Without seeds there would be no ‘so called’ modern animal husbandry. As time passed by crop production achieved higher and higher yields so the grains became available not for just humans but for animals as well. This contributed in the spread of the swine and poultry farming, as a result for nowadays these become the most consumed species. The seeds are essential parts of the complete feeds, which are the primary food source for the intensively kept swine and poultry stocks. To fulfil their role in modern nutrition these feed have to undergo various kinds of treatments depending on what kind of plant it is. We can distinguish two major groups depending on whether the technology is applying heat or not.

2.1. 8.2.1. Seed treatment methods without using heatThe pounding and its variation are belonging to this group. The purpose of the pounding can be various. The most important is the breakdown of the plant tissues thereby improving the digestibility. With the breakdown of tissues the digestive fluids (enzymes and other fluid matters) are able to decompose in a larger surface and access better to the cell content thus the efficiency of the utilisation of nutrients are improving. This can be well seen in the figure where the changes of the barley’s nutrients digestibility (Laurinen et al. 2000.) depending on the size of the pounding can be observed (Table 35).

9.1. ábra - Table 35. The effect of the grinding for the digestibility of nutrients of barley in pigs

The pounding also has the advance that raw materials with different size and density become mixable which is the basis of homogenous feed preparation. Of course this method also has disadvantages too. One can be the oxidation of nutrients in the feed. Until the seed is not decomposed the oxygen is not able to get to the nutrients containing double bounds, so the oxidation cannot occur. As a result of pounding the oxygen-free condition is terminated and the oxidation processes immediately begin. Thus it is that the seeds are almost stored in whole and not in a grind form. Another disadvantage of grinding is that as a result of the treatment dust is generated. On the one hand this leads to nutrient loss on the other hand it is unhealthy for the animals (poultry are the most sensitive to it). For ruminants pounding causes other problems by accelerating the digestion of the feed in the rumen and in parallel with this the generation of organic acids (primarily propionic acid). This large amount of organic acid may reduce the pH in the rumen which has a negative effect on the microbes and through this the animal’s nutrition utilisation decreases. Depending on the technology the pounding methods can be divided into three groups:

Milling

It is the most ancient method for pounding the feed, the technology has gone through several changes over the years. In the beginning, the cereal grains were milled between two stones by hand, and as time went by people invoked wind, water and later the steam to move the mill stones. Today’s technology is the roller pounder, which has a very simple working principle (Figure 35).

9.2. ábra - Figure 35. The operation of roller pounder (1. spout, 2. valve, 3. rollers, 4. gap controller, 5. electro-motor)


8. FEED PROCESSING

Two rotating rollers are milling against each other with different speeds. The fineness of the product can be influenced with the roller’s speed and distance from each other. The end product of milling is flour, which is characterised by consistent grain size.

Grinding

While milling is mainly used by milling industry and has importance in human alimentation, grinding is typically used in animal feed production. The grinding is usually carried out by hammer grinder, this means that hammers are located in the middle of a rotating perforated drum and during the operation the rotating hammers are throwing the seeds to the surface of the drum and because of this the seeds are broken. When the size of the grain is smaller than the perforation of the drum, the broken grain falls out from the drum (Figure 36).

9.3. ábra - Figure 36. The operation of the hammer grinder (1. motor, 2. coupling, 3. rotating part, 4. hammer, 5. air inlet, 6. suction fan, 7. ventilator, 8. grind surface, 9. basement, 10. control plate, 11. hindering plate against snapping back, 12. spout, 13. screen)

This product is called grind, and its size is not as homogenous as the flour’s. The size of the grind is determined by the size of the perforation, the rotation speed of the hammer and the drum and the water content of the grain. The size of the grind determines the digestibility of the feed and the homogeneity of the feed mixture. The optimal particle size depends on the animal species, the age and the feeding technology.

Cracking

Cracking is the least common used form of pounding. It is used specifically for ruminants where the goal is to break the grain into few pieces. For ruminants it is important not to crush the grains into too small pieces because this way feed spends less time in the rumen and this impairs the digestibility of the feed. The primary goal of the technology is not to leave any whole grain in the feed. The cracking is usually made by rollers. The method is very similar ones which are used in milling, but the distance between the rollers are much bigger, so we get cracked grains not flour.

2.2. 8.2.2. Heat treatmentsNowadays there are not produced any mixed feed which basic commodities do not undergo some kind of heat treatment. This may be primary due to that different heat treatments have positive effect on the value of the feeding. This is a favourable change depending on what kind of feed we are talking about this can be traced back to two major factors. For cereal seeds the goal is to improve the digestibility of the starch which can be helped through the heat treatment both by physical and chemical changes. The chemical change is the


8. FEED PROCESSING

gelatinization of the starch, which greatly improves the efficiency of the digestion (Holm et al., 1988). The physical changes are due from the increase of the surface (bloating, flacking) which makes the digestive enzymes more efficient. The case is different with legumes, legumes cores features antinutritive matters, and the inactivation of these are essential, if we would like to use these plants. Since the legume seeds are the main protein source thus the protein utilisation is a priority. Unfortunately these antinutritive matters are primarily impeding the protein breakdown; in order to successful feeding utilization this problem must be solved. Although this problem primarily occurs in legume seeds the method is also used for other plants. Depending on whether the heat treatment happens in dry or wet conditions we can determine dry thermic treatments (air dry seeds or their grind heat treatment) and wet thermic treatments (treatment of grains by moisture with steam or water, and their grinds).

Boiling

One of the oldest heat treatment, which we use daily in human alimentation but its usage in animal feeding is overshadowed, because it is difficult to insert into modern feeding systems. Basically it was a preparation method for legumes and potato. The aim was mainly to inactivate the antinutritive matters (potato-solanin), but it also increases the digestibility of the starch.

Roasting

Roasting is a kind of process that is not really used nowadays. It was specially used in swine farming when the cereals (mainly barley) were roasted for the pigs. In the process the barley was roasted until brown in 150-160°C. During this time the starch in the barley was broken down into maltose units which sweet flavour was preferred by the pigs. Taking the advantage of this it was much easier to accustom the animals from the milk to the dry feed. Due to the heat many proteins and vitamins were damaged, and this of course it was negative, but in this case the aim was not to improve the nutritional effect but to accustom to the dry feed.

Toasting

This is an essential process for soybean treatment. Soy products which are currently marketed for use of feed almost always undergo this procedure. The soy contains trypsin inhibitor, which decreases the protein digestion efficiency of the animal (Marsman et al., 1997). To avoid this, the effect should be neutralized. Toasting serves this purpose. The whole meal or extracted grind is treated next to steam at 100-105°C for 30 minutes. During this time the substance, which is lowering the efficiency of digesting, inactivates (the net protein utilisation improves with more than 20%), and the feed is ready for use. The operation is carried out in special toasters.

Flaking

Generally it is typical that if something is invented in feeding, which can be used both in human and animal nutrition, first they investigate whether it can be used for animal nutrition and if it does they try to introduce it to the human nutrition. With flaking and a few other treatment methods the story had the opposite way. It first appeared in human nutrition and later in animal husbandry. The first flake was introduced by the Kellog brothers and it started its world wide spread from here. The usage as a feed only a decade later got into the farmers’ head. The technology’s essence is the following: the cereal grains are steam heated at 100-120°C and then the softened cells are flattened between a roller pairs (Figure 37).

9.4. ábra - Figure 37. The process of flaking (1. spout, 2. rollers, 3. wetting auger, 4. steamer, 5. jig, 6. flaker, 7. dryer-cooler, 8. ventilator)


8. FEED PROCESSING

Due to the treatment the grain can be flattened without becoming broken. This process helps to fix the gelatinising starch, and due to the flattening the flakes can be quicker dried.

Expanding

This is a widespread feed treatment method during which the whole grain is treated. The feed is heated with steam in enclosed space, and a big difference in the pressure is generated and the grain suddenly swollen into its multiple size. The advance of the technology is that the digestibility of the starch is better and the granulation performance improves, a better quality granule can be made, more liquid feed supplement can be added to the granules, and the microbiological condition of the feed also improves.

Extruding

Nowadays a modern feed mixer cannot operate without extruder machines. The technology was developed in the USA 50 years ago, but until now, it is still an essential part of the feed making. The point is that the ground cereal grains are pressed with high-pressure steam, which makes the material to become spongy state (Figure 38).

9.5. ábra - Figure 38. The process of the extruding (1. spout, 2. grinder, 3. extruder, 4. dryer-cooler, 6. grinder)

It should be interesting that during the process there are two grinding. The first grinding is important to increase the efficiency of the method. The second one is just for the mixing, because the extruded final product is unmixable to any other raw materials, so the grinding is necessary. Depending on how much steam is used during the process the product may be dried at the end. After flaking, expanding and extruding the product is ground again and only the carry out the granulation process.

Granulation

One of the most important and often the last step of the compound feed production (it may happen that the finished granules are covered with fat, for energy restoration and for the creation of an oxygen-free environment). The aim is to make uniform size and homogenous complete feeds in a form in which it easily can be transported and stored (Figure 39).

9.6. ábra - Figure 39. The granulation (1. ring jig, 2. deflectors, 3. roller cross, 4. rollers, 5. knife, 6. pellet)

Due to pressing, the density of the feed increases which results in a less volume accompanied by the same weight. Due to the subsequent fat covering the inside of the particle is not connected with air, and so it is dryer than the air-dry state (12-14% water content), we get a 6-8% water content feed. This means a great economic advantage in transporting and moving large amounts of feed, because there is 6-8% more feed in the same


8. FEED PROCESSING

weight.

3. Test questions:1. What kind of process the inactivation of anti-nutritive matters?

2. Why the heat treatments are so important at the seeds?

3. What is the difference between expanding and extruding?

4. Describe the different kinds of pounding methods?

5. What kinds of factors are influenced by the chaff size?

4. Recommended readingMcDonald, P., Edwards, R.A., Greenhalgh, J.F.D., Morgan, C.A., Sinclair, L.A., Wilkinson, R.G. 2011. Animal nutrition. Seventh edition. Pearson Education, Limited. Harlow, UK.

Moughan, P.J., Verstegen, M.W.A., Visser-Reyneveld, M.I. (Eds). 2000. Feed evaluation principles and practice. Wageningen Pers. Wageningen, NL.

Patience, J.F. (Ed). 2012. Feed efficiency in swine. Wageningen Academic Publishers.


10. fejezet - 9. IMPACT OF DIETARY NUTRIENTS ON IMMUNE STATUS OF ANIMALS1

In recent years nutritional research has focused on the impact of different nutrients on animal health and on how the supplemental and the feed’s own nutrient can manipulate the immune functions in livestock.

It is well known that the immune status of the animal is highly dependent on their nutrient consumption. According to the relevant research findings many important interactions exist between the nutrition and the physiological processes in animals, involved in its immune function and production (growth, reproduction, etc.) (Koutsos and Klasing, 2006). However, it can also be stated, that the optimum dietary regimes (nutrient concentrations in the diet and feed ingredient selection) is influenced by the immune system status of the pigs being feed (Stahly, 2010).

Nowadays objective of feeding is not only improvement of the fattening and other performance data, but maintenance of the animals’ health as well.

Specific and non-specific immune response of the organism is triggered by contacts with the pathogens. Maintenance of the active immune response needs an elevated nutrient and energy supply related to the baseline that can be originated from the feed, or in lack of feed from disruption of the own tissues. Active metabolism of cells of the immune system need glucose, amino acids and fatty acids, but of course the suitable vitamin and mineral supply is also vital precondition for the fast and effective immune response (Meijer, 2006). Role of vitamins and minerals in improvement of immune status of the farm animals has been pretty well known (Koutsos and Klasing, 2006), but relatively limited information is available on the influence of some macronutrients (amino acids, unsaturated fatty acids, etc.). Therefore, the present chapter is focusing on the impact of macronutrients on immune status of animals.

1. 9.1. DEVELOPMENT OF THE NUTRITIONAL IMMUNOLOGYNutritional immunology focusing on common areas of the two disciplines provides a new approach in the animal science: It tries to search how a healthy organism can be prepared to activate an enhanced resistance triggered by an infection or other stressor so that the production parameters can be maintained during the enhanced immune response phase (Halas et al, 2006). This possibility would mean complete removal of some feed additives (i.e. antibiotics) from the feed while the animals’ production could be maintained. Although the question – how the animals’ immune status can be modulated via nutrients – comes basically from the human nutritional science, results of animal experiments (first of all mice- and rat studies) carried out in the human research can many times be utilized in the animal nutritional immunology research as well.

The nutritional immunology has a relatively short history, the year 1810 can be considered as its beginning, when the scientists discovered that atrophy of the lymphoid tissues can be attributed to malnutrition too. The early 1900s were the age of discovering the vitamins. The beginning was characterized by incomplete knowledge of the immune system. At that time role of nutrient and vitamin supply was concluded on the basis of symptomatic signs of decreased resistance due to malnutrition or vitamin deficiencies. Clinical use of the penicillin, discovered by Fleming, was started by Dubos, who had used the first antibiotic for routine treatment of many bacterial diseases. The period between 1939 and the late 1950s is called the age of antibiotics in the nutritional immunology. Feed of the farm animals has been supplemented with small amounts of antibiotics since the 1950s in order to improve their productivity. By now this type of antibiotic use has been actually forbidden due to the well known reasons. “Interactions of nutrition and infection”, the article by Scrimshaw, Taylor and Gordon published in 1959 can be considered as the end of flourishing of antibiotics and beginning of the new era. The authors published a lot of examples on highly positive correlation of the nutrient supply of the organism and its resistance against different pathogens. The new era can be considered as the beginning of the

11* This chapter is based on the following publication: Halas V., Kovács M., Babinszky L. 2006. Impact of nutrient supply on the immune functions in pig. Magyar Állatorvosok Lapja. 9: 533-543. (in Hungarian with English abstract)


9. IMPACT OF DIETARY NUTRIENTS ON IMMUNE

STATUS OF ANIMALSmodern nutritional immunology. The dynamic development characterizing the era was due to fast development of the immunology and the related analytical and methodological procedures from the 60s (Keusch, 2003). At this time problems related to nutritional immunology were studied on systematically designed animal models, based on immune response generated by lack of one or more nutrients. In the 80s a part of the studies focused on correlation between nutrient supply of the farm animals and immune status of the animals. This is the start of the independent nutritional immunology. It has to be noted though that some results of the human nutritional immunology – those of lab animal studies – has still been utilized by the animal nutritional immunology.

From the 90s researchers focused not only on the decreased resistance caused by the different nutrient deficiencies, but their objective was determination of optimal doses of the different nutrients for growing and for the effective immune function. Even the early literature data prove that the two values can be different many times. For example higher amino acid intake doesn’t cause a higher weight gain, but it can result in a better immune status of the animal.

2. 9.2. INFLUENCE OF THE NUTRIENT SUPPLY ON THE IMMUNE FUNCTION 2.1. 9.2.1. Protein and amino acid supplyProtein supply of the farm animals, i.e. the swine is not only important for the optimal gain and production, but for maintenance of the immune status as well. In case of protein deficient feeding (3 vs. 23% protein) immune response of the 4-week-old piglets was much weaker than herdmates supplied with protein matching their demand for growing. According to human studies in case of protein malnutrition decrease in number of T cells, first of all T helpers, decreased production of secretory IgA and other antibodies and poor phagocyte activity can be expected. However animal experimental data show that moderate reduction in protein level of the feed doesn’t decrease antibody mediated immune response markedly. Authors note that some antigens (i.e. sheep red blood cells, E. coli) change protein metabolism of the organism so that protein synthesis in some organs responsible for the immune response (i.e. bursa Fabricii, liver) is elevated, while protein synthesis of the muscles is decreased. Thus moderate reduction in the protein supply in case of an alarmed immune system causes decrease in protein gain of the body, but the animals’ ability for a cellular and humoral immune response is not necessarily decreased.

Protein content of the feed may influence not only the general immune response, but local immune response of the digestive tract as well.

Data of some studies conclude that an elevated N-excretion can be expected in case of diseases caused by bacteria, virus or parasites due to the altered metabolism of the organism and the enhanced immune function. However some authors call the attention to the fact that amino acid composition of proteins utilized during the inflammation process or other defence mechanisms is markedly different from that of the body proteins. That means that immune responses are determined by not just the protein supply, but by quantities of the different amino acids as well. The immune system needs relatively more phenylalanine, thyrosine, tryptophan, cystein and serine, while leucine, lysine, hystidine, arginine, alanine, asparagine, and glutamine, requirement of the animal body is not higher than that of the growing. Results of different studies conclude that sulphur containing amino acids, moreover theronine, arginine and glutamine has a most important role in defence system of the organism (Defa et al., 1999).

Influence of the amino acids on the immune system is demonstrated by the example of the threonine.

Apart from the lysine the threonine is one of the most frequent limiting amino acids in the swine feeds. However it was found in studies focusing on nutrient demands that while lysine is the primary limiting amino acid of the N-retention, threonine takes part not only in building up the body proteins, but in building up proteins playing active role in the immune system as well. A lot of studies conclude that in case of swine and other breeds (poultry, rabbit, man) amount of threonine needed for growing is not enough for establishment of an optimal immune status. Threonine is one of the main components of the y-globuline that is present in the organism in high amounts, mainly as IgG. That means that if the animals are fed with antibiotic-free feed – when immune status of the organism plays a leading role in the fight against pathogens – threonine demand of the antibody-production (IgG) apart from that of growing has to be taken into consideration as well.

Defa et al. (1999) studied swine of 17 kg body weight. The feed given to the animals differed only in its



STATUS OF ANIMALSthreonine content (5,9 – 8,9 g/kg). Results of the study showed that feeds with threonin level over 6,8 g/kg could not improve production data of the grower pigs. However IgG concentration of the blood and antibody production following an immunization with bovine serum albumine markedly elevated in the animals that were given a feed containing 8,9 g/kg threonine (Table 36). Other authors state that in case of an incomplete threonine supply, development of organs playing role in the immune system doesn’t necessarily change, but deterioration of some immune parameters can be expected, i.e. leukocyte proliferating ability of the blood may decrease.

10.1. ábra - Table 36. Effect of dietary threonine on serum IgG and bovine serum antibody production in pigs (Defa et al., 1999)

The above and other results has led to the conclusion that nutritional immunology would play a leading role in the practical feeding in the near future, and, on the other hand, the nutrient recommendations have to be reconsidered based on results of the nutritional immunology studies.

2.2. 9.2.2. Fat, fatty acidsDeterioration of the health status is characterized by decrease of feed consumption. For the continuous growth the reduced nutrient supply can be compensated by a more concentrated feed. Energy concentration of the diets can be increased easily by adding fats or oils to the feed.

Saturated fatty acids

The concentrated, energy-rich feed is a cardinal point of piglet rearing and suckling sow feeding. However it is well known that fat supplementation reduces the immune response capacity. In a study with weaned piglets animal fat supplementation of the feed (20% fat in the feed) reduced the humoral immune response ability of the animals. Piglets were immunized with Escherichia coli lipopolysaccharide. At the same level of digestible energy (DE) intake lymphocyte blastogenesis and antibody titers against ovalbumine were significantly lower in the piglets fed by a high fat content feed compared to the animals fed by a high starch content feed. In case of mice the feed rich in saturated fatty acids (20% fat) resulted in a weaker hypersensitivity late type reaction. However it has to be noted that fat supplementation in the above studies was very high (20%). It is well known, that fat content of the diets is not higher than 12% under practical swine feeding conditions (Flachowsky, 2005). It is remarkable that no clear literature data prove that continuous increase of the fat content and/or 12% fat content can result in immune suppression. Nevertheless the results call the attention to the fact that fat supplementation of the feeds in order to increase their energy level cannot be applied limitlessly, as in case of high doses – apart from problems of the digestive physiology – deterioration of immune status of the animals can also be expected.

Unsaturated fatty acids

Animal experiments prove that immune status of the body (chemotaxis of the polymorphonuclear granulocytes, phagocytosis and cytotoxic activity of the macrophages) markedly decreases if essential unsaturated fatty acid level of the feed is lower than the requirement. Immune deficiency due to fatty acid deficiency can be considered as an analogue to the reduced immune status due to incomplete supply of other nutrients (Calder and



STATUS OF ANIMALSField, 2002). However n-3 and n-6 fatty acids given in high amounts above requirements result in a reduced immune response ability as well. Literature data show that while 5% of fish oil can improve cytotoxicity of the natural killer cells in lab animals (mice, rat), feeding 20% fish oil markedly decreases their activity. Immune suppressive effect of the unsaturated fatty acids could not be cleared yet, but some hypotheses give a possible explanation to their immune modulating effect. Quality and saturation of the dietary fats determines fluidity of the membranes. Membrane fluidity increases if amount of polyunsaturated fatty acids (PUFA) is higher in phospholipids of the cell membrane. The membrane fluidity plays a leading role in the cell-to-cell interactions, receptor function, and the intercellular signal transmission system as well. As number of unsaturated bounds grows higher, oxidative stress will be higher too, that can result in an elevated lipidperoxidation – if antioxidants are not given to balance the process. Apart from the above the n-3 fatty acids may take part in regulation of the gene expression too. Some authors think that immune suppressive effect of the lipids can be explained by the influence of the dietary fat on the cytokin production (de Pablo et al., 2000).

Two groups out of the polyunsaturated fatty acids got an extra attention due to modified immune response ability of the organism. One of them is the n-6, the other is the above mentioned n-3 fatty acids. While the n-6 fatty acids (linoleic acid, arachidonic acid, docosapentaenoic acid) promote inflammation processes by means of increasing number of polymorphonuclear granulocytes and enhancing prostaglandin production, the n-3 fatty acids (linolenic acid, eicosapentaenoic acid, docosahexaenoic acid) have an anti-inflammatory effect.

2.3. 9.2.3. CarbohydratesAlmost half of the energy content in the compound feed is given by carbohydrates, first of all starch. During the digestion process starch brakes down to monosaccharides, and absorbs as glucose. It is important to know whether starch and glucose have an influence on the immune response ability of the organism.

Starch

It was found in chicken studies that feeds supplemented with maize starch can be utilized by the immune suppressed organism more effectively to compensate the fallback caused by stress compared to fat supplemented feeds (Benson et al., 1993). Defence against pathogens is an energy demanding process for the organism that needs glucose as primary energy source. The elevated glucose consumption has a positive effect on the gluconeogenesis, while fatty acid oxidation in the liver decreases and amount of very low density lipoproteins increases. In vitro studies show that the very low density lipoproteins reduce immune response reactions first of all by inhibiting the lymphocyte and polymorphonuclear granulocyte functions. Experiments prove that starch supplementation of feed to increase energy content helps reducing gluconeogenesis in swine, thus the higher glucose supply due to the starch content may help immune response capacity of the organism in stress situation.

Non-starch carbohydrates (NSP)

Nowadays use of by-products in swine feeding has increased. Parallelly NSP content of the diets has become higher as well. Amount and quality of NSP consumed with the feed influences not only digestibility of the nutrients but possibly immune status of the animals as well, via its influence on structure of the mucous membrane of the guts and on composition of the gut microflora (Lim et al., 1997, Pluske et al., 2010). Based on the latest scientific findings it is clear, that the relationship between nutrition, immunology and gut hearth status are very strong (Varley and Miller, 2006). Binding of bacteria to the gut wall, endotoxins and/or lipopolysaccharids of the pathogens stimulate immune competent cells of the gut and enhance local immune response of the organism. Some studies call the attention to the fact that if fibre content of the feed is originated from pectin mainly, local immunity of the rat gut improved compared to the other group fed by feeds containing fibres of cellulose or mannan in 5%. In case of 5% pectin content number of T-helper-1 (Th1) cells and amount of IgA and IgM increased in the gut-associated lymphoid organs. Th1 cells play an important regulating role in the inflammatory and cytotoxic processes, thus they are vital for the specific defence against intracellular pathogens.

Feeding advantages of the different fibre types have only been studied in the last years. Some of them can be used fruitfully as prebiotics (i.e. fructo- and mannan oligosaccharids). At the moment no swine study is available on immune stimulating effect of other fermentable NSP materials, but results of lab animal studies (rat, mice, dog) show that these fermentation products improve local resistance of the guts. Though further studies for clearing the mechanisms are needed, it’s probable that suitable choice of components when composing the feed can improve local immunity of the guts.

Summarized it can be stated that nutrient demand recommendations for farm animals, first of all swine that has



STATUS OF ANIMALSonly considered requirements of maintenance and production are not always meet the nutrient requirements of a good immune status. Results of the different studies prove that moderate decrease of the protein supply related to the optimum demands doesn’t cause incomplete immune function. However supply of some amino acids (i.e. threonine) above the requirements of maintenance and growing may result in an enhanced immune status. In case of some nutrients (i.e. methionine, unsaturated fatty acids) the amounts given above requirements can result in immune suppression even before decrease of production could be observed. Although role of the different nutrients in the immune function needs further research. It can be stated that immune status of the animals could be improved by means of regulating the components and some nutrients (amino acids, unsaturated fatty acids) in the compound feeds.

3. Test questions:1. Which are the most important milestones of the development of nutritional immunology?

2. Which important amino acid has an immune status modulating effect?

3. Which important carbohydrate has an immune status modulating effect?

4. Which important polyunsaturated fatty acid has an immune status modulating effect?

4. Recommended readingDefa, L., Changting, X., Shiyan, Q., Jinhui, Z., Johnson, E.W., Thacker, P.A. (1999) Effects of dietary threonine on performance, plasma parameters and immune function of growing pigs. Animal Feed Science and Technology 78. 179-188.

Garnsworthy, P.C., Wiseman, J. 2001. Recent Developments in Pig Nutrition 3. Nottingham University Press. UK.

Klasing, K.C., Leshchinsky, T.V. 2000. Interactions between nutrition and immunity. In: M.E. Gershwin, J.B. German, C.L. Keen. (Eds). Nutrition and immunology: Principles and practice. Humana Press, Totowa, NJ. USA.

Meijer, J.C. 2006. Nutrition and Immunity in Farm Animals. In: Wiseman, J. and Garnsworthy, P.C. (Eds). Recent Developments in Non-Ruminant Nutrition. Nottingam University Press. UK.


11. fejezet - 10. EFFECT OF ANIMAL NUTRITION ON PRODUCT QUALITY1. 10.1. TYPES OF MEAT QUALITYNowadays feeding experts frequently face the question: How the quality of food commodities of animal origin (meat, milk, egg) can be influenced by means of feeding so that it can be more appropriate for the human nutrition demands.

In order to answer the question, quality of the product has to be determined, and all the factors contributing to the quality of a product have to be well known.

Studying the relevant literature it can be stated that no uniform definition exists for example for the meat quality. Generally it is determined as a complex of organoleptic, nutritional physiological, toxicological, hygienic and processing-technological factors. However according to Hoffman’s definition (1993) meat quality is all features and characteristics of the meat that are important from the point of view of nutritional value, human health and processing.

Based on the literature it is quite clear that different members on different places of the production – retail chain have different ideas on meat quality.

Usually four different qualities are distinguished:

1. Hygienic quality: Characteristic to microbiological status of the meat.

2. Technological quality: Refers to suitability of the meat to further industrial processing.

3. Culinary (eating) quality: Expresses physical status, flavour and water holding capacity of the meat.

4. Quality related to nutritional value: Refers to the suitability of the meat for human nutrition (i.e. protein and fat content and their ratio, mineral and vitamin content).

2. 10.2. QUALITY, SAFETY AND ACCEPTABILITY OF ANIMAL ORIGIN FOODSTUFFSIf meat quality is studied from the point of view of nutritional physiology, a somewhat modified definiton is got, not touching the essence. Nutritional physiology prefers meats poor in fat, but the meat going to the market is required to be free from toxins, external hormonal products, and from other substances harmful to the human organism as well.

It has to be noted that the terms “quality”, “safety” and “acceptability” are not synonyms. Determination of the quality has already been touched above.

Food safety means that if the consumer prepares and eats the given foodstuff properly, it can be guaranteed that the product won’t be harmful for the consumers’ health during the whole

production and retail chain. The food safety is a system of more components, and always refers to a specific enterprise and activity.

However, acceptability of a specific foodstuff, as it is shown in Figure 40. can only be mentioned if it has suitable quality, and is safe. The last to terms may somewhat overlap each other as it can be seen in the Figure 40.

11.1. ábra - Figure 40. Relationship among food safety, quality and acceptability (Mossel and van Logtestijn, 1989)


10. EFFECT OF ANIMAL NUTRITION ON PRODUCT

QUALITY

3. 10.3. EFFECT OF NUTRIENT INTAKE ON MEAT QUALITYExperiences show that the quality of the meat or other animal products can be influenced by means of feeding, and this is true for the other environmental factors as well.

Method and intensity of feeding, amount, quality of feed consumed and their relation to each other are the most important feeding factors that can have an influence on the meat quality. However it has to be noted that some chemical feed additives and medicaments used not properly may also influence, mostly negatively the quality of the meat or other food commodities of animal origin.

Two examples show influence of the feed on the meat quality.

During the last years studies with omega-3 polyunsaturated fatty acids (PUFA) in swine and poultry feeding and also in the human nutritional research have come into focus.

Results of the clinical studies show that consumption of these fatty acids alleviates or even fully eliminates some diseases (coronary heart problems, psoriasis, some inflammations).

They improve health, vision development of the premature born babies, skin health status of the adults, brain function and production of some hormones.

The omega-3 polyunsaturated fatty acids are present in the fish oils in high quantities. Results of some studies show that if feed of the fattening swine is supplemented with fish meal or fish oil, amount of long carbon chain omega-3 polyunsaturated fatty acids can be increased in the pork. However faulty flavours in the pork may be felt when the swine were fed by feed containing fish oil in such a low amount as 1%. In several European countries the consumers prefer pork to fish meat, thus fish flavour of the pork triggers a more intense reaction.

Linolenic acid is a shorter carbon chain omega-3 polyunsaturated fatty acid that can be found in the plant oil, i.e. in the rape oil in larger quantities. The “double zero” (low erucic acid, low glucosinolate content) and low fibre content breeds can be used fruitfully in the swine and poultry feeding.

Research results show that 6% rape oil mixed to the feed may result in higher omega-3 fatty acid content of pork and poultry meat.

Meat quality can be examined not only on the basis of its unsaturated fatty acid content, but on the basis of other factors as well. From the point of view of the human nutritional physiology, perhaps one of the most important characteristics is protein and fat content of the meat, the protein/fat ratio in the meat, and amount of the intramuscular fat.



QUALITYProtein and fat deposition of the grower and finisher swine is influenced by several factors. Most important among them is the genetically determined protein deposition ability and feed intake capacity of the animal. Correlation between the two factors is described in more theories. Out of them the linear plateau principle, which states that protein deposition increases in direct proportion to the energy intake till the genetically determined protein deposition threshold, is the most frequently used one (Figure 41).

11.2. ábra - Figure 41. Linear-plateau and curvilinear relationship between protein intake and protein deposition in case of two different energy intakes (Bikker, 1994)

Growth performance and chemical composition of the carcass (i.e. meat quality) is highly affected by the different amino acid/energy ratios of the feed. As in case of swine lysine is the primary limiting amino acid, in order to increase the protein deposition, the most favourable lysine energy ratio (DE) should be established when the mixed feed is composed. As it was mentioned in Introduction („Challenges in the 21st century animal nutrition”) results of the relevant studies show that in case of hybrid swine of average genetic capacity (average daily weight gain 800 g), the lowest fat deposition in the first part of the finishing (between 20 – 45 kg live weight) at a ratio of 0,63 g ileally digestible lysine (IDLYS/MJ DE), (Figure 42) while that in second half of the finishing (between 45 – 105 kg live weight) in case of 0,5 g IDLYS/MJ DE can be expected.

11.3. ábra - Figure 42. The effect of altering the ratio of lysine/digestible energy on the fat content of growing pigs (LW: 20-45 kg) (Batterham et. al., 1990)



QUALITYThe lysine energy ratio is different in case of hybrids of high genetic capacity (average daily weight gain 1000 – 1100 g, or even higher). In the diet of these swine 0,7 g IDLYS/MJ DE between 20 – 45 kg live weight (Figure 43) and 0,6 g IDLYS/MJ DE ratio between 45 and 105 kg live weight should be provided, otherwise fat content of the meat will be higher, thus meat quality will be poorer.

11.4. ábra - Figure 43. Lysine and digestible energy requirements for improved pigs (Varley, 2001)

Results of the above studies prove that there is a possibility to improve quality of food commodities of animal origin (i.e. meat) by means of feeding so that it can be more appropriate for the human nutrition demands. However it has to be noted that the not lege artis composed feed may lead to the opposite result, quality of the product will be poorer, that may cause serious losses for the farmer.

4. Test questions:1. List and characterize the meat quality categories.

2. Give the definition of meat quality.

3. What is linear plateau concept?

4. What IDLYS/MJDE ratio is proposed in the feed of a hybrid swine of average genetic capacity in growing and fattening period?

5. Recommended readingBabinszky, L., Halas, V. 2009. Innovative swine nutrition: some present and potential applications of latest scientific findings for safe pork production. Italian Journal of Animal Science. 8. (Suppl. 3): 7-20.



12. fejezet - 11. RELATIONSHIP BETWEEN ANIMAL NUTRITION AND ENVIRONMENTAL POLLUTION1. 11.1. NUTRITION AND ENVIRONMENTAL POLLUTIONThe two most critical environmental pollutant elements are nitrogen and phosphorus if damage to the nature and eutrophication of waterbodies are considered, thus emission of these elements should be limited when environmental friendly management and feeding technologies are worked up. Decreasing emission of excess microelements should also to be focused on. The highest nitrogen- and phosphorus pollution in the farm animal agriculture is produced by the swine and poultry industries. Specialities of digestion of these two animal breeds and the not suitable crude protein and amino acid supply, and shortcomings of substandard management and those of manure handling can contribute to this pollution as well. Some 7400 tons of phosphorus and more than 35 000 tons of nitrogen are excreted to the environment by the Hungarian swine industry at the present number of animals (Babinszky, 2012).

Possibilities to decrease nitrogen emitted to the environment by the animal agriculture depend on several factors, i.e. technical, technological, legal, economical, ethical, and last, but not least, biological factors.

The professional feeding may contribute to reduction of nitrogen excretion of the swine and poultry industry. A precondition to this is the appropriate amino acid supply of the animals meeting their requirements and reduction of crude protein content in the grain mixes. In order to reach this purpose, digestible amino acid content of the mixed feed components have to be calculated when diets are formulated and the amino acid requirement should be given as digestible amino acid.

2. 11.2. REDUCTION OF NITROGEN EXCRETIONPossibilities to decrease nitrogen and phosphorus emission are shown on swine feeding examples below.

The studies of Flachowsky (1995) prove that if crude protein content of the diets are decreased by 20% while they are supplemented with crystalline amino acids, nitrogen excretion of the finisher swine can be reduced by some 30% without decrease of their performance (Table 37). According to Rademacher (2000) nitrogen excretion of the finisher swine can be decreased by some 35% if crude protein content of the diet is reduced. Results of this study show that every 1 % decrease in crude protein content of the mixed feed result in 10 – 12,5% less ammonia emission. Thus results of the relevant literature show that rate of N-emission by swine of different age and utilization can be decreased by means of more exact determination of the amino acid requirements, establishment of the modern protein evaluation systems (ileal digestible amino acid content) and establishment and extensive use of the ideal protein concept.

12.1. ábra - Table 37. Reducing the protein content of diets and impact of amino acid supplementation on the nitrogen excretion of fattening pigs (Flachowsky, 1995)


11. RELATIONSHIP BETWEEN ANIMAL NUTRITION AND

ENVIRONMENTAL POLLUTION

Improvement of digestibility of amino acids in the feed components, choosing an amino acid ration better meeting the age requirements, phase feeding of piglet rearing and finishing period, and reasonable utilization of industrially produced amino acids offer further possibilities for the reduction. These potentially available feeding tools make reduction of both the N- and P-emission possible by some 20 – 30%, without a decrease in the animals’ performance (Babinszky and Vincze, 2002).

3. 11.3. REDUCTION OF PHOSPHORUS EXCRETIONResults of international research projects show that the swine utilizes just some 30% of phosphorus consumed with the feed for maintenance and production, the other 70% is excreted via faeces and urine (Table 38).

Reduction in phosphorus content of the diets is justified basically by two factors: Environmental pollution caused by phosphorus overfeeding and the excess expenses caused by the excess anorganic phosphorus supplementation.

If relatively low price of the dietary phosphates is considered environmental pollution caused by the phosphorus is of higher importance nowadays.

The phosphorus pollution can be decreased in two ways. First if the requirements are met by supplementation based on digestible phosphorus content, or by means of improving digestibility of the phosphorus. By means of establishment of phosphorus requirements given in digestible phosphorus, different digestibility of phosphorus content, thus different digestible phosphorus content of the feed components can be taken into consideration.

12.2. ábra - Table 38. Phosphorus retention in growing pigs by several author

Studies suggest that phosphorus content of the maize digested the least while that of the wheat the best. This is the explanation to the fact that although the total phosphorus content of the two plants is almost identical, a marked difference in their digestibility can be observed. The different digestibility can be explained by different phytate content of the feedstuffs and the different own (native) phytase activity. Under effect of the own phytase only 10% of the phytate content of the maize, while 48% of the wheat become absorbable. Relevant research


11. RELATIONSHIP BETWEEN ANIMAL NUTRITION AND

ENVIRONMENTAL POLLUTION

results show that digestibility of the native phosphorus can be improved by supplementing the feed by industrially, biotechnologically prepared phytase enzyme. As a result of the better phosphorus digestibility, anorganic phosphorus supplementation of the feed can be decreased so that less phosporus can be emitted to the environment.

Table 39 shows changes in phosphorus balance of the grower pigs at different phytase levels. Data of the experiment show that if phosphorus is supplied according to the recommendation (control group) amount of phosphorus excreted via faeces decreases when phytase enzyme is given to the diet that can be explained by improvement of the phosphorus digestibility. However excess phosphorus absorbed from the guts is excreted via urine that suggests that the animals had phosphorus stores beyond their requirement. Result of the experiment shown below calls the attention to the fact that when the diet is supplemented by phytase enzyme, total phosphorus content of the feed may be reduced by at least 10 – 20% without marked changes in phosphorus retention of the swine.

12.3. ábra - Table 39. Effect of different phytase doses on phosphorus balance in growing pigs (25-60 kg LW)1 (Tossenberger et al., 1994)

Data of the experiment also call the attention to the fact that it is not advisable to mix phytase enzyme to diet of the grower pigs (between 20 – 60 kgs live weight) in higher amount than 500 FTU/kg feed, as in case of a higher dose (1000 FTU/kg feed) retention of phosphorus won’t improve substantially, but mixing the enzyme to the feed in such a high concentration results in excess feed costs.

Thus results of the studies prove that total phosphorus content of the swine feed mixes can be reduced when phosphorus requirement is given in digestible phosphorus, and when digestibility of the native phosphorus content (of plant origin) in the feed is improved by means of phytase enzyme supplementation of 500 FTU/kg feed. More correct meeting the phosphorus requirements may contribute to the reduction of phosphorus emission that results in important environmental advantages.

4. Test questions:1. What kind of feeding methods are known to reduce nitrogen excretion of the swine?

2. To what extent can the nitrogen excretion be reduced by means of the applied methods?

3. What kind of feeding methods are known to reduce phosphorus excretion of the swine?

4. What is the recommended phytase dose in the swine feed for a profitable production?


Wiseman, J., Garnsworthy, P.C. (Eds). 2006. Recent Developments in Non-Ruminant Nutrition. Nottingham University Press. UK.


13. fejezet - 12. IMPACTS OF CLIMATE CHANGE ON FEED CROP PRODUCTION, ANIMAL PRODUCTION AND QUALITY OF ANIMAL FOOD PRODUCTS1

1. 12.1. THE EFFECT OF CLIMATE CHANGE ON FEED CROP PRODUCTIONIt is very well known that agriculture is very sensitive to climate variability and extreme weather events, such as droughts, floods and storms etc. The forces that shape our climate are also critical to farm productivity. Human and industrial activities have already changed plenty of atmospheric properties, such as temperature, precipitation, concentration of carbon dioxide in the air and ozone at ground-level. The experts forecast that these trends will continue. While food production may benefit from a warmer climate, the increased risk of droughts, floods and heat waves will pose challenges for agriculture.

There are three distinct types of photosynthesis: C3, C4, and CAM (Crassulacean Acid Metabolism). C3 photosynthesis is the typical photosynthesis used by most plants. C4 and CAM photosynthesis are both the outcome of adaptation to arid conditions because they result in better water use efficiency. In addition, CAM plants can save precious energy and water during harsh times, while C4 plants, in contrast to C3 plants, can photosynthesize faster under the high heat and light conditions of the desert, because they use an extra biochemical pathway and special anatomy to reduce photorespiration.

The three different types of photosynthesis can be characterized as follows (http://wc.pima.edu/Bfiero/tucsonecology/plants/plants_photosynthesis.htm):

C3 Photosynthesis: C3-plants – with stomata open during the day – get their name from CO2 being first incorporated into a 3-carbon compound. The enzyme involved in photosynthesis is called Rubisco, and it is also involved in the uptake of CO2. Photosynthesis takes place throughout the leaf. Their adaptive value is more efficient under cool and moist conditions and under normal light than that of the C4 and CAM plants because it requires less machinery (fewer enzymes and no specialized anatomy). Most plants are C3.

C4 Photosynthesis: C4 plants are called so because the CO2 is first incorporated into a 4-carbon compound. Their stomata are open during the day. They use PEP (Phosphoenolpyruvate) Carboxylase as the enzyme involved in and enabling a very fast uptake of CO2, which is then "delivered" to Rubisco for photosynthesis taking place in the inner cells. In contrast to C3 plants this photosynthesis occurring under high light intensity and high temperatures is faster because CO2 is delivered directly to Rubisco, not allowing it to grab oxygen and undergo photorespiration. Water Use Efficiency is better too, because PEP Carboxylaze brings in CO2 faster and so the stomata do not need to be kept open that much (less water lost by transpiration) for the same amount of CO2 gain for photosynthesis. C4 plants include several thousand species in at least 19 plant families.

CAM Photosynthesis: CAM plants are named after the plant family in which it was first discovered (Crassulaceae) and because the CO2 is stored in the form of an acid before being used in photosynthesis. The stomata are open at night (when evaporation rates are usually lower) and are usually closed during the day. The CO2 is converted to an acid and stored during the night. During the day, the acid is broken down and the CO 2 is released to Rubisco for photosynthesis. In contrast to C3 plants the water use efficiency of this group is better under arid conditions due to their stomata being open at night when transpiration rates are lower (no sunlight, lower temperatures, lower wind speeds, etc.). CAM plants include many succulents such as cacti and agaves,

11 This chapter is based on the following publication: Babinszky, L., V. Halas, M.W.A. Verstegen. 2011. Chapter 10: Impacts of climate change on animal production and quality of animal food products. In: J. A. Blanco and H. Kheradmand (Eds): Climate Change, Socioeconomic Effects. InTech Open Access Publisher. 165-190.


12. IMPACTS OF CLIMATE CHANGE ON FEED CROP PRODUCTION, ANIMAL

PRODUCTION AND QUALITY OF ANIMAL FOOD PRODUCTS

and also some orchids and bromeliads (http://wc.pima.edu/Bfiero/tucsonecology/plants/plants_photosynthesis.htm).

The increase in temperature usually favors species with C4 type photosynthesis, which are better from several aspects than the C3 type species. Worth highlighting of these are the high net productivity of photosynthesis and the fact that they use significantly less water per unit of dry matter production. In addition, for C4 plants the CO 2

absorbing capacity of PEP-carboxylaze – the primary enzyme of CO2 fixation – is more than 30 times higher than that of RuDP-carboxylaze, and consequently they are also able to absorb more efficiently any CO2 released during photorespiration. This is particularly advantageous for C4 plants under stress conditions (high temperature, aridity, high photo intensity), as they are not forced to rely on CO2 replenishment through the stomata. Under such circumstances the stomata remain closed, which substantially reduces the loss of water caused by transpiration.

Peer reviewed studies also report that besides the increase in temperature and aridity, the third dominant environmental element of climate change, i.e. the increase of atmospheric CO2 concentration is more favorable for the C3 photosynthesis species. Due to the simultaneous change of these three factors in the future, it is difficult to make predictions either at the level of the biosphere or of the natural and artificial biocoenoses. In case of the most prevalent weed in Hungary, i.e. the common ragweed, the simultaneous increase of the two abiotic factors (temperature, carbon-dioxide concentration) equally favored the production of biomass and of pollen, and also the initial phenophase of the flowering period shifted to an earlier time.

Of the 18 weed species considered to be the most dangerous worldwide, 14 belong to the C4 group, while of the 15 crops most important for global food supply only 3 species are C4. In consequence, the result of any increase in the carbon-dioxide concentration is that in the competition between weeds and crops the competitive ability of crops in the agroecosystems is enhanced, and thus their weed suppressing potential is strengthened (Babinszky et al., 2011).

The impact of climate change on feed crop production also influences the feed base of farm animals because it affects the yield, quality and price of forage and concentrate crops, since – as mentioned before – the photosynthesis of C4 feed crops (corn, sorghum, millet) is more efficient, their heat and drought tolerance is better than those of the C3 crops (wheat, barley, rye, oat, sunflower, alfalfa, soy).

In summary it can be concluded, that climate change has a major impact on feed crop production. Thus for instance C3 plants will face more stress in consequence of higher temperatures and of any eventual decline in the annual amount and/or change in the annual distribution of precipitation. For this reason the selective breeding of plants will have to focus on selecting for drought resistant varieties of C3 plants for example in order to avoid loss of yields.

Nutritionists are also going to face a serious challenge. Using the latest results of animal nutrition and its related disciplines (microbiology, immunology, physiology, molecular biology, precision nutrition, information technology, etc.) they are to develop feeding technologies and feed formulas in which the latest feed crop varieties of improved drought resistance are used more extensively. All this should be used in the everyday practice of producing foodstuffs of animal origin besides avoiding any decline in the quality and safety of the product (foodstuffs of animal origin) and alleviating the environmental load of livestock production.

2. 12.2. THE IMPACT OF CLIMATE CHANGE ON THE PERFORMANCE OF FARM ANIMALS AND THE QUALITY OF ANIMAL FOOD PRODUCTS2.1. 12.2.1. Thermoneutral zone and thermoregulation of farm animalsIn order to better understand how climate change affects livestock performance it is necessary to become acquainted with the bases of livestock production, and particularly with the processes pertaining to the utilization of dietary energy, since the ambient temperature has a major impact on the energy metabolism of food producing farm animals. The concept and importance of the thermoneutral zone and the thermoregulation




of the animals are briefly reviewed below for this purpose.

Physiological processes are associated with heat production, which is the sum total of non-productive energy utilized by the animal and of the energy “lost” in the course of converting the dietary nutrients. The non-productive energy is used for maintenance, i.e. it satisfies the energy requirement of such essential physiological processes as the maintenance of the body temperature, the nervous system, organ functions, ion pumping, energy requirement for minimal activity, etc. The total of heat produced in the course of digestion, excretion and metabolism of nutrients is called heat increment. Within a certain range of ambient temperature and besides unvarying feed and nutrient intake the total heat production of the animal remains constant (Figure 44).

13.1. ábra - Figure 44. Relationship between ambient temperature and heat production of farm animals

This temperature range is called the thermoneutral zone. In a thermoneutral environment the heat production of the animal is at the minimum, and thus the dietary energy can be used for production (growth, egg and milk production) efficiently. Unfavorable temperatures (too cold or too hot environments) lead to an increased heat production by the animal, i.e. there is more loss of energy, and in consequence less energy remains for production at the same level of energy intake, and the efficiency of energy utilization deteriorates. The upper and lower critical temperatures for different animal species and age groups are shown in Table 40. The species, age and body condition of the animals all have a significant influence on the critical temperature, but other environmental factors affecting their thermal sensation and heat dissipation, such as air velocity and air humidity, are also crucial.

13.2. ábra - Table 40. Lower and upper critical temperature of farm animals at different age or body weight (FASS, 2010)




Increasing the airflow improves the efficiency of evaporative cooling, but higher humidity has the opposite effect. In cold, humid conditions the heat conductivity of wet hair increases, thus the animal becomes more sensitive to the lower ambient temperature. Based on these examples it can be seen that in case of high humidity levels the comfort zone of the animals becomes narrower, the lower critical temperature increases while the upper critical temperature decreases.

Thermoregulation is the ability of the animals to maintain their body temperature in cold or hot environments, consisting of behavioral, physiological and anatomical responses that affect energy metabolism. In a cold environment the rate of oxidation increases, in other words, the body “burns” more nutrients, thus boosting its heat production, in order to compensate for the higher heat loss caused by the lower ambient temperature. Shivering is a tool aiding this process; since the energetic efficiency of muscle work is low, the resulting heat production is quite significant. If heat loss exceeds heat production, the result will be hypothermia and death. As the thermoregulatory mechanisms of newborn and young animals – particularly in swine and poultry species – are poorly developed, the cold environment increases the number of mortalities. According to predictions a characteristic feature of climate change will be the rising average temperatures, and this may become an advantage for the survival rate of young animals.

From a practical perspective higher temperatures are much more hazardous for growing/finishing and breeding animals than a cold environment. Temperatures exceeding the higher critical level compromise animal performance not only by changing the energy and nutrient metabolism, but also by upsetting the body homeostasis, with detrimental consequences both for immunocompetence and for product quality. In general, livestock with high production potential are at greatest risk of heat stress, thereby requiring the most attention (Niaber and Hahn, 2007). Therefore, in the present chapter the high temperature induced metabolic changes and its consequences will be discussed in detail.

2.2. 12.2.2. The effect of heat stress on the production of pigs and pork quality




Due to length reasons the effect of heat stress on pig production will only be discussed in the present chapter.

Pig performance and pork quality

The climate change with rising mean temperatures may cause a permanent stress load for pigs, especially in continental summer or warmer climate areas. As shown in Table 1, the upper critical temperature for pigs from nursery to adult ages is 25-26 ºC; however, some research data suggest that the optimal temperature decreases with the increase in body weight. The heavier animal, the less ability it has to lose heat due to the relative small surface area compared to its body weight. In consequence feed refusal increases with body weight at high ambient temperatures (Close, 1989; Quiniou et al., 2000).

In case of sows kept at high ambient temperatures (29oC vs 18oC) the feed intake over the entire lactation period may fall back by more than 50%, resulting in a loss of body condition far exceeding the optimum and also leads to poorer growth of the piglets (Table 41).

13.3. ábra - Table 41. Effect of ambient temperature on performance of multiparous lactating sows (Quiniou and Noblet, 1999)

The condition of the sows is also in close correlation with the number of days to oestrus and the reproductive performance. Studies with pair fed sows showed that the energy metabolism and hormonal status of the animals changed during heat stress and the lower milk production is not exclusively explained by the reduced feed intake (Prunier et al., 1997; Messias de Bragan et al., 1998). Feeding high fat diets (125 g fat per kg of dry matter) to the sows during lactation in order to alleviate hyperthermia leads to decreased heat production, which may reduce the feed refusal of the sows kept at high ambient temperatures (Babinszky, 1998). Feeding high fat diets also improves the energetic efficiency of milk production when compared to sows fed high starch diets (with low dietary fat levels, Table 42). From the aspect of energetic efficiency milk fat production is more efficient from dietary fat than from dietary carbohydrates because it is converted more directly (Babinszky, 1998).

13.4. ábra - Table 42. Effect of dietary energy source on the energy balance of lactating sows >and on the energetic efficiency of milk production (Babinszky, 1998)




Since the milk production of the lactating sow determines the performance of the suckling pigs in terms of their growth rate, mortality and morbidity, any reduction in the milk yield will have a negative impact on the profitability of pig production. Moreover, heat may also compromise the parameters of fertility: the quality of eggs and sperm deteriorates; embryo mortality between days 1 to 15 increases and maturity is delayed. In consequence, the number of piglets per sow may be less when sows are exposed to high ambient temperatures for longer periods of time.

High temperatures cause loss of appetite in pigs; however, both the upper critical temperature and the rate of feed refusal are influenced by the relative humidity of the air (Collin et al., 2001; Huynh et al., 2005). With the increase of humidity a 60 – 70 kg pig may lower its feed intake by up to 80-150 g/day (Huynh et al., 2005). The lower feed intake compromises the daily gain, however, after exposure to hot periods of 30-33ºC pigs display compensatory growth, they overcome their heat stress and grow further, but they can’t compensate for temperatures as high as 36ºC (Babinszky et al., 2011). There is a curvilinear relationship between the increase of temperature and the average daily gain and feed conversion rate of pigs fed ad libitum (reviewed by Noblet et al., 2001). The average daily gain reaches its maximum between temperatures of 15 to 25ºC in young pigs (up to 30-34 kg) and between 10-20ºC in growing and finishing pigs. Both cold and severe heat stress compromise feed conversion; however, during moderate heat stress (2-3ºC above the upper critical temperature) pigs have the ability to compensate for the lower feed intake by decreasing their maintenance related heat production. Besides constant heat stress, diurnal high temperatures can also be detrimental to pig performance. The average daily feed intake and the average daily gain decreased by 10 and 20%, respectively, and the feed conversion (feed/gain) increased by approximately 8% when pigs were kept in a daily range of 22.5 to 35ºC in contrast to the thermoneutral (20ºC) temperature. In the interest of performance and immune response it is recommended to avoid any higher fluctuations (±12ºC) of the mean of 20ºC (Noblet et al., 2001).

Recent publications highlight the fact that high temperatures not only impair growth but also change body composition and thus can impair the nutritive value and quality of pork. Prolonged heat stress (30-33ºC) reduces the rate of protein deposition in growing and finishing pigs. The lower protein deposition is probably not just in consequence of the lower nutrient supply. Halas et al. (2004) demonstrated in their model simulation that the rate of protein deposition is sensitive to any changes occurring in the maintenance energy requirement of the body. Heat stress triggers hormonal changes that influence the metabolism of nutrients. Reduced levels of thyroid hormones were consistently observed in swine kept in a hot environment in contrast to a thermoneutral milieu (Messias de Bragan et al., 1998; Renaudeau et al., 2003). Thyroid hormones are responsible for the metabolic rate and thermogenesis besides influencing the protein turnover within the body. Although carcass fatness decreases as a result of lower feed intake during heat stress, the shift of fat distribution from external sites towards internal sites was found to be attributable to a reduced activity of the lipogenic enzyme in backfat and a higher activity of lipoprotein lipase in lean fat (Noblet et al., 2001).

In conclusion, heat stress impairs feed intake and swine performance in the lactating sow and in growing and fattening pigs. The extent of this detrimental effect depends mainly on body weight and the actual temperature and relative humidity of the air. Recent studies show that growing and fattening pigs kept in hot environments




deposit less protein, which compromises pork quality with regard to the protein to fat ratio in the meat. Any means of reducing heat production or increasing heat loss of the animals are beneficial in the efforts to avoid the weakening of the production potential of swine when facing with global warming.

3. 12.3. FEEDING STRATEGIES IN RESPONSE TO CLIMATE CHANGE3.1. 12.3.1. Feeding strategies during cold stressAs earlier mentioned, animals consume more feed at low ambient temperatures in order to compensate for the increased energy requirement used in thermoregulation. From the aspect of energy requirements a cold environment is essentially the equivalent of reduced energy supply, and thus higher feed intakes and higher energy intakes can meet the extra demand of thermogenesis. When the increased feed intake is prevented by the limitations of the animal’s gastro-intestinal system, any means of boosting the dietary energy of the feed may be suitable for maintaining growth, and egg and milk production. Although increasing the dietary energy in a thermoneutral environment is associated with the improvement of feed conversion (the amount of feed required to produce 1 kg of product), in cold ambient temperatures, however, feed conversion may become worse or in the best case does not change with the feeding of high energy density diets due to the higher use of maintenance – i.e. non-productive – energy.

The body attempts to compensate for the excessive heat loss suffered in cold temperatures by a higher rate of heat production, and one component of this is to increase the use of maintenance energy. Heat, however, is also generated in the course of digesting and converting the dietary nutrients (the thermic effect of diet), which helps to maintain body temperature in conditions below the lower critical temperature; accordingly the feeding of diets with a high thermic effect will help the animals cope with the too cold environment. Thus for example, when high fiber diets are fermented by the colon bacteria a relatively high portion of energy is lost as heat; and the oxidation of proteins / amino acids as a form of energy producing process also produces lot of heat. Therefore, feeds containing a high percentage of fermentable fibers or excess protein increase the heat production of the animals. In practical feeding, however, protein overfeeding is not recommended either from the economical or the environmental point of view.

3.2. 12.3.2. Feeding strategies during heat stressSince heat production after ingestion of the diet is high, farm animals reduce their feeding activity at high ambient temperatures, which bears significant consequences on their nutrient intake. The practice of feeding the daily ration in several smaller portions or during the cooler parts of the day follows from the above. Based on the previous sect1s other potential feeding strategies can be applied at the time of heat stress, which

1. reduce the heat production by the animals;

2. compensate for the lower nutrient supply; and

3. alleviate heat stress induced metabolic changes. It should be noted, however, that during severe heat stress these methods should be used in combination in order to maintain the production performance of the farm animals and the quality of their products.

Methods to reduce the total heat production of livestock

Methods to reduce total heat production of farm animals consist of

1. fat supplementation,

2. feeding low protein diets with synthetic amino acids according to the ideal protein concept, and

3. adding dietary betaine.

1. In comparison to other nutrients, fat generates the least heat, either when deposited as body fat or when used for energy, thus high fat diets reduce the total heat production of the animals. Accordingly, fat




supplementation moderates feed refusal, which is critical for the production potential. At the same time, fat supplementation boosts the energy density of the diet, as the energy content of fat sources (both of plant and of animal origin) is far the highest compared to the other nutrients and to compound feeds. By adding fat to the diet the energy requirement of the animals can be met accurately even if the feed intake decreases to some extent above the upper critical temperature.

2. The so-called ideal protein refers to a well-defined amino acid pattern, which expresses the requirement of essential amino acids in percentage of lysine. The amino acid pattern of the ideal protein changes to some extent during the life of the animals in accordance with their level of production. Amino acid conversion and N excretion are the lowest when diets are formulated according to ideal protein concept. Excess amino acids that cannot be used in protein synthesis due to a limiting factor (such as a limiting amino acid, energy supply or genetic potential) are metabolized in the body. Compared to other nutrients, the oxidation of amino acids yields the most heat contributing to the total heat production. Consequently, the heat increment is higher when excess amino acids are present in the diet. The heat increment from protein metabolism is at the minimum if the dietary protein level meets the requirements of the animal, and if the amino acid content or even the ileal digestible amino acid content corresponds to the ideal protein concept.

3. Betaine (trimethylglycine) is an intermediate metabolite in the catabolism of choline, which can modify the osmolarity, acts as a methyl donor, and has potential lipotropic effects. Schrama et al. (2003) showed that under thermoneutral conditions dietary betaine supplementation (1.23 g/kg) reduced the total heat production of pigs. Moreover, recent studies repeatedly recommend using betaine in pig and poultry feeds during heat stress, as being a methyl donor it can be used in the antioxidant defense (for glutathione-peroxidase) system, and it also efficiently inhibits the reduction in cell water retention.

Compensating for reduced nutrient supply

Since heat stress impairs feed intake and the digestibility of nutrients too, it is recommended to feed more concentrated diets with high levels of easily digestible nutrients in hot environments. This should be implemented with the use of various options offered by the feed manufacturing technologies (hydrothermic treatments, micronization), and also by increasing the level of dietary vitamins and minerals, and perhaps by improving their bioavailability. The bioavailability of nutrients can be achieved in part by enhancing the digestibility of nutrients in the small intestine (ileal digestibility) and also by boosting the utilization of absorbed nutrients (e.g. use of organic trace elements). Adding different enzyme supplementation to the diet can improve the ileal digestibility of nutrients, such as amino acids, carbohydrates and Ca and P. It is suggested, however, to use substrate specific dietary enzymes (phytase, xylanase, β-glucanase, etc.) in accordance with the composition of feed.

Alleviating heat stress induced metabolic changes

The third group of nutritional strategies aims to alleviate the heat stress induced metabolic changes within the body. These are means to enhance the oxidative defense or alleviate the shift in electrolyte balance within the body. Several micronutrients possess direct or indirect anti-oxidative properties; those most extensively examined in farm animals are vitamin C, E and A, zinc and selenium as well as methionine. The defense of farm animals against lipid peroxidation; also the body requires more of these antioxidants during heat stress. This is why it should be stressed, that vitamin and mineral supplementation not always leads to the improvement of production performance or product quality of animals kept in hot environments, even though they are essential to maintaining their health status. The excretion of Na and K and the amount of water lost from the body increase during heat stress, which together may lead to a shift in the acid / base balance. Supplementing monovalent ions in the diet can lessen the decrease of water retention by the body. Salts suitable for the purpose are ammonium chloride, sodium and potassium bicarbonate, sodium and potassium hydro carbonate, potassium sulphate, etc., which can be equally used in poultry, swine and ruminant nutrition.

With respect to alleviating the non-desirable consequences of climate change, the combined application of the options discussed in the above can counteract the negative impact of conditions outside the comfort zone of farm animals.

4. 12.4. CONCLUSION




In summary it can be concluded that we should expect climate change to cause long-term changes in the environment, which in turn affect feed crop production and the production of farm animals.

An important task facing feed crop breeders is to create C3 feed crop varieties that as a result of the selective breeding efforts become more drought tolerant besides maintaining their average yields and nutrient contents. It will be our task as nutritionists to use these improved feed crop varieties in a highly focused and professional manner when formulating diets.

When developing professional animal nutrition however, we should not only rely on traditional nutritional science but should also use the results of its related disciplines (microbiology, immunology, molecular biology, molecular genetics, digestive physiology, etc.) besides having a thorough knowledge of the energy metabolism of farm animals. As discussed earlier, there is a very close relationship between the energy metabolism of the animals and the ambient temperature, and the animal performance and the quality of their products. The knowledge of these factors enables us to alleviate by means of nutrition the stress caused by climate change and in consequence to produce high quality and safe foodstuffs meeting the requirement of human nutrition without increasing the environmental load of production.

5. Test questions:1. Characterize the C3 and C4 plants.

2. Describe the relationship between ambient temperature and heat production of farm animals.

3. Give the possible feeding strategies during cold stress.

4. List the possible feeding strategies during heat stress.


Babinszky, L., Halas, V., Verstegen, M.W.A. 2011. Impacts of climate change on animal production and quality of animal food products In: J. A. Blanco and H. Kheradmand (Eds.): Climate Change, Socioeconomic Effects. InTech Open Access Publisher. 165-190.



14. fejezet - 13. CONCEPT OF THE TOTAL AND ANIMAL NUTRITION1. 13.1. PRECISION LIVESTOCK FARMING (PLF)Information science and information technology are having a rapidly growing impact on the methods used in livestock production. Precision livestock farming (PLF), which is based on these concepts, is a leading example. Using electronic information transfer, PLF applies principles of control engineering in optimizing production and management processes. PLF consists of measuring variables on the animals, modeling these data to select information, and then using these models in real time for monitoring and control purposes. Thereby, PLF is currently regarded as the heart of the engineering endeavor towards sustainability in (primary) food production. Its application allows making optimal use of knowledge and information in the monitoring and control of processes.

A first step in PLF is monitoring, collecting and evaluating data from on-going processes. Collection of data from animals and their environment, by innovative, simple and low-cost techniques, is followed by evaluation of the data by using knowledge-based computer models.The research scope ranges from monitoring feeding times, feed intake, and performance parameters to real time analysis of sounds, images, live weight assessment, condition scoring, on-line milk analysis and more. The final aim is to achieve a full picture of the state of the animals (cows, pigs, chicken, etc.) and their environment on a continuous basis, regarding the main parameters of animal health, animal behavior and animal performance. PLF has a great potential in developing the technology for continuous automatic monitoring and improvement of animal health, animal welfare, quality assurance at farm and chain level, and for improved risk analysis and risk management (Cox, 2007, Banhazi et al; 2012)

In order to be able to produce safe, uniform, cheap, environmentally- and welfare-friendly food products (and market these products in an increasingly complex international agricultural market), livestock producers must have access to timely production related information. Especially information related to feeding/nutritional issues is important, as feeding related costs are always significant part of variables costs for all types of livestock production. Producers also need to install systems that will assist them in implementing best-practice management procedures on livestock farms to ensure that the available resources are efficiently used and consumer requirements are satisfied. Therefore, automating the collection, analysis and use of production related information on livestock farms will be essential for improving farm productivity in the future. Electronically-controlled livestock production systems with an information and communication technology (ICT) focus are required to ensure that information is collected in a cost effective and timely manner and readily acted upon on farms. The precision animal nutrition is an important part of Precision Livestock Farming.

2. 13.2. PRECISION ANIMAL NUTRITIONPrecision nutrition, as can be seen in (Figure 1, see Introduction), applies the research findings of traditional nutrition and of the new areas of animal nutrition, using large databanks with the help of computer technology. Precision nutrition consists of meeting the nutrient requirements of animals as accurately as possible in the interest of a safe, high-quality and efficient production, besides ensuring the lowest possible load on the environment (Nääs, 2001). Precision nutrition is also called “information intensive nutrition”. American and Australian examples prove that in the near future precision nutrition will be of key importance in producing pork economically and in high quality, and thus also in the innovation activities.

Precision nutrition is one of the newest and most dynamically evolving fields of animal nutrition. The concept was developed in the USA. By applying precision nutrition, the farm animals (i.e. primarily cattle, sheep, pig, and poultry) are fed so that their nutrient requirements are met with the maximum possible precision, ensuring thereby the most efficient and safest production of animal products, the best product quality and at the same time the lowest level of environmental pollution. The concept is based on information technology and the extensive international databases. It’s more important fields are: review of the most recent requirement levels by species, age groups and categories; factors influencing the requirements; interactions between nutrients and minerals and vitamins; determining the requirements and predicting the product quality using mathematical programs (models); the potential for reducing N, P and CH4 excretion using various feeding systems and


13. CONCEPT OF THE TOTAL AND ANIMAL NUTRITION

technologies.

Precision animal nutrition consists of meeting the nutrient requirements of animals as accurately as possible in the interest of a safe, high-quality and efficient production, besides ensuring the lowest possible load on the environment. This is facilitated by electronic feeding based on IT technology, an important but by far not the only tool of precision nutrition.Some of the most important elements of precision animal nutrition are:

• Application of recent scientific findings in diet formulation;

• Apply stringent quality control of ingredients and compound feeds;

• Application of the ileal digestibility concept in amino acid nutrition;

• Using of the ideal protein concept in diet formulation;

• Reduction of the harmful effects of heat stress in animals with different nutritional tools;

• Reduction of the harmful effects of mycotoxins in animals with different nutritional tools;

• Application of the recent findings of the molecular genetics in animal nutrition;

• Application of the recent findings of the nutrition immunology;

• Application of the recent findings of the molecular genetics in animal nutrition (animal nutrition based on genetic profile);

• Using feed additives on the properly way;

• Reduction of the N and P excretion by nutritional tools;

• Using phase feeding;

• Using Split-sex feeding;

• Application of total nutrition concept;

• Application of high developed electronically-controlled feeding systems with an information and communication technology (ICT);

Many of these elements were discussed in different chapters of the present lecture note.

3. 13.3. TOTAL ANIMAL NUTRITIONIt is one of the greatest challenges of animal agriculture in the 21st century to produce food materials from animal origin of the proper quantity, quality and safety in a traceable production chain while imposing the least possible environmental load. Producing high quality, safe and traceable food in the required quantity is an especially important strategic question for all countries.

It is also a known fact that the quality of food of animal origin is greatly determined by the nutrition of animals. Therefore, animal nutrition can have a key role in solving the previously mentioned problems in lots of cases. The respective statistical data show that more than 700 million tons of compound feed for farm animals was produced in the world in 2012. It is obvious that the quality of this enormous amount of mixed diet can have a determinant effect on the quality of foods of animal origin. The situation can be further worsened by the fact that

in many countries, animals are also fed diet of uncertain origin, consisting of uncontrolled ingredients. Therefore, the agricultural industry has to face the following important tasks in the 21st century (Babinszky and Halas, 2009):

1. Much more active and conscious participation in production of the proper quantity, quality and safe foods of animal origin.

2. In order to reach this goal, it is especially important to further improve the efficiency of animal nutrition



(biological efficiency, nutrition technological efficiency, economic efficiency).

3. It is especially important to rethink the interrelation between animal nutrition, animal husbandry and environmental protection. This means that good quality and safe food of animal origin can only be produced by using a technology which does not pollute the environment any further, i.e. it is necessary to work out environmental-friendly nutrition systems which could lead to the reduction of nitrogen and phosphorus output.

One effective response to these demands is using the concept of total nutrition, which is an approach to animal nutrition where feed hygiene, food security, food safety and maintenance of animal health are all considered as feed objectives (Adams, 2001). The concept of total nutrition is an integral part of the precision animal nutrition (Figure 45).

To understand total nutrition we need to understand the ulinks between diet, health, disease and environment. In practical circumstances animals consume a great diversity of different molecules in feed over and above those from the conventional nutrients. The molecules found in diets according to Adams (2001) can be categorized into two major groups, nutrients and nutricines.

14.1. ábra - Figure 45. The concept of total nutrition (Adams, 2001)

Nutrients are generally recognized as feed components such as proteins, carbohydrates, fats, fiber, minerals and vitamins, etc. Nutricines are dietary components that exert a beneficial effect on health and metabolism, yet are not direct nutrients. The nutricines include antioxidants, emulsifiers, colors, enzymes, flavors, non-digestible oligosaccharides, organic acids, etc. The efficiency of nutrient conversation to animal origin products (meat, eggs, milk, etc.) depends on many factors, e.g. housing of animals, feed quality, feed intake capacity of animals, rate of digestion and rate of absorption of the nutrients, the efficacy of nutricines, immune and health status of the livestock and last but not least on stress. The stress factors can be divided into two major groups (Adams, 2001):

1. Metabolic stress: oxidation, non-infectious diseases, immune stimulation, immune suppression, formation of harmful intermediate metabolites in the body, etc.



2. Environment stress: pathogens, vaccinations, toxins, heat stress (Babinszky et. al., 2011), cold stress, activity (fighting) stress, feed raw materials (Babinszky, 1998), etc.

It can be concluded that in order to proper supply of nutrients and production of high quality and rentable animal food products in animal nutrition we should taking into account all factors covered by the total nutrition concept.

4. Test questions:1. Give the definition of precision animal nutrition.

2. List the most important elements of the precision animal nutrition.

3. Give the definition of total nutrition concept.

4. List the most important elements of total nutrition concept.

5. Recommended readingAdams, C. A. (Ed). 2001. Total nutrition: feeding animals for health and growth. Nottingham University Press. UK.

Babinszky, L., Halas, V. 2009. Innovative swine nutrition: some present and potential applications of latest scientific findings for safe pork production. Italian Journal of Animal Science. 8. (Suppl. 3): 7-20.

Banhazi, T., Babinszky, L., Halas, V., and Tscharke, M. 2012. Precision Livestock Farming: Precision feeding technologies and sustainable livestock production. International Journal of Agricultural and Biological Engineering. 4: 54-61.

Cox, S. (Ed). (2007). Precision livestock farming. Wageningen Academic Publishers, Wageningen, NL.


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