Poultry Feedstuffs Supply Composition and Nutritive Value

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Poultry_Feedstuffs_Supply_Composition_and_Nutritive_Value/Poultry Feedstuffs Supply Composition and Nutritive Value/0851994644Ch1.pdfPART IPresent and future supply of feedstuffs

Poultry f_s - Chap 01 29/5/02 11:20 AM Page 1


CHAPTER 1Agronomic and political factorsinfluencing feedstuff use

R.W. Dean Dean Agricultural Associates, London, UK

CAB International 2002. Poultry Feedstuffs: Supply, Composition and Nutritive Value(eds J.M. McNab and K.N. Boorman) 3

In agronomic terms and in the context of the global trading economy, it isappropriate to look at feedstuffs use for livestock production on a worldwidebasis. Account must be taken of demographic factors such as populationgrowth and urbanization. Incomes are also a significant determinant of live-stock product consumption and, thus, the use of feedstuffs. Significantincreases in demand for livestock products, and thus feedstuffs, are predicted inthe early years of the next century, the bulk of which will occur in the develop-ing world, most notably in China and South-East Asia. Pressures on land usewill emphasize the role of increased crop yields in supplying requisite feed vol-umes. Declining rates of crop yield increase thus give cause for concern. Thepotential of biotechnology in squaring this equation is examined together withgrowing political opposition to such techniques. The importance of emphasiz-ing the role of science in livestock production and feedstuffs usage is stressed1.

This chapter discusses some of the agronomic and political influences on feed-stuffs use.

In agronomic terms and in the context of the global trading economy, it isincreasingly appropriate to look at feedstuffs use for livestock production on aworldwide basis. In addition, there is a need to look at other factors that haveentered the equation in more recent years. These factors apply with particularforce in certain regions of the world.

Agronomic factors to be investigated include cropping area and produc-tivity. Account must be taken of demographic factors such as populationgrowth and urbanization. Incomes are also a significant determinant of live-stock product consumption and, thus, the use of feedstuffs. Nor may culturalfactors be ignored.

It will be shown that political factors are now becoming a significant inputinto livestock production systems, particularly in those parts of the westernworld rich enough to afford such sentiments.

1This paper was revised and updated in October 2001.

INTRODUCTION AND OBJECTIVES


No attempt is made to generate specific forecasts of feedstuffs usage.Instead, general indications are given, based on the predicted evolution of themain factors identified in the agronomic analysis.

It is virtually impossible to quantify all use of livestock feedstuffs on a world-wide basis.

In the first place, a significant proportion of livestock feeding takes placeoutside the purview of the formal economy in the non-commercialized sector.To some extent, data are not easily accessible even for those feedstuffs pro-duced on an industrial basis.

In the 2000/01 cereal year, it is estimated that 683 million tonnes of wheatand coarse grains were used to feed livestock worldwide (USDA FAS, 2001).This volume represents approximately 47% of wheat and coarse grain usagefor all purposes. Over the past 10 years, use of grain for livestock feed hasincreased at an average annual rate of 0.6%.

Use of coarse grains for feedstuffs accounted for 582 million tonnes in the2000/01 season; approximately two-thirds of all consumption. Over the past 10years, use of coarse grains in feed has increased by an average of approxi-mately 0.9% per year. In contrast, just over 100 million tonnes of wheat wasused to feed livestock last season, representing 17% of all wheat consumption.

Since the 19th century, the crushing of oilseeds for human consumptionhas yielded a valuable input for livestock production. In the 2000/01 season,175 million tonnes of oilseed meals were consumed worldwide, of which two-thirds was soybean meal. Average growth in the consumption of oilseed mealsduring the past 7 years has been 3.5%. This highlights the increasingly indus-trial nature of feedstuffs production as the requirement for higher protein feedconstituents has become apparent, notably in poultry and pig production.

The evolution of large-scale urbanized industrial societies in the west during thelast quarter of the 19th century and the first 75 years of the present century wascharacterized by significant increases in the consumption of livestock products.This has been driven by increases in population and disposable income and byfalls in the real relative price of livestock products.

In traditional societies, meat eating is reserved for ceremonial or festiveoccasions and the bulk of both energy and protein nutrition is derived fromfoodstuffs of vegetable origin. Such production of livestock as takes placeoccurs on a non-commercial basis. Consumption of livestock products is largelyconfined to intermediate products such as eggs or milk. The rural nature ofsuch societies, the inadequacy of a distribution system and the frequentabsence of electricity for essential refrigeration reinforce this.

4 R.W. Dean

FEEDSTUFFS THE WORLD SCENE

THE EVOLVING PATTERN OF LIVESTOCK PRODUCTCONSUMPTION


In traditional societies, cultural and religious prohibitions also play animportant role in determining patterns of livestock product consumption andfeedstuffs usage. Such prohibitions might or might not be modified along withthe changing social and economic nature of society. They will, however, playan important role in determining the early shape of such development as doestake place. For example, it is difficult to envisage, certainly in the short tomedium term, the evolution of a successful beef-based livestock product indus-try in India in those regions where the predominant religious tradition and prac-tice is Hindu; similar considerations apply to pork in the case of Islam.

Significantly, no society displays obvious significant religious-culturalrestraints on poultrymeat or fish consumption.

In recent years, there have been significant changes in the worldwide pattern oflivestock product consumption.

In the developed world, income elasticities of demand for livestock prod-ucts have fallen sharply. This will be discussed in more detail subsequently, butthe significance of the income variable in the consumption function has dimin-ished relative to other considerations.

In emerging economies, notably those of Asia and, in particular, China,demand for livestock products is increasing very rapidly, albeit this process hasbeen interrupted by economic difficulties since 1996, less so in China than inPacific Rim countries. This is a function of, in some but not all cases, expandingpopulation, rising money incomes and increasing urbanization.

Population growth worldwide appears to have peaked in the late 1960swhen it stood at 2.1% a year. This factor underpinned the Club of Romesreport in 1972 predicting a crisis of Malthusian proportions. This has, so far, notensued because of falling rates of population growth and the effects of theGreen Revolution in agricultural production. Longer-term projections from theUnited Nations suggest that, for the first 20 years of the next century, popula-tion growth will average 1.4% annually. This will be divided into 0.4% for thedeveloped countries and 1.7% for the developing nations. Another source sug-gests that, from a total of 6 billion in 2000, world population is expected togrow to 7.5 billion in 2020, equivalent to an average annual rate of growth of1.1%.

The role of urbanization, as people seek work in cities and towns, is animportant element in determining the demand for livestock products and thusfeedstuffs. In 1960, around 22% of the population of the developing countriesresided in urban areas. By 1980, this figure had increased to 30% (Pinstrup-Anderson, 1992). One study suggested that, by 2000 and as a result of theextraordinary growth of industry in China and other Asian countries, urbandwelling in the developing countries would account for 44% of the population.In global terms, it has been noted that, during the 20th century, the worldspopulation grew from 1.5 billion to 6 billion; the urban population grew from200 million to around 3 billion, half the total.

Factors influencing feedstuff use 5

CHANGING CONSUMPTION PATTERNS


A number of studies have suggested that urbanization exerts a significanteffect on qualitative food demand. Dietary transitions noted include a moveaway from staple crops such as sorghum, maize and millet towards cerealsrequiring less preparation time and, significantly, towards livestock products andother processed foods. Also, significantly, such studies which have been carriedout in Asia note not only a substantial increase in the demand for livestock prod-ucts but also increased preference for wheat relative to rice (Bouis, 1994).

Urbanization is a by-product of economic growth and, in recent years, eco-nomic growth as measured by GDP has been significantly greater in the devel-oping countries, notwithstanding economic disruption in Asia and theremarkable evolution of the US economy in the 1990s. One author, discussinglong-term projections for Asian economic growth in the early 1990s, com-mented that the high growth rates in developing countries are projected tocontinue in future (Rosegrant et al., 1995). This prediction was not borne outby events, but there remained little doubt that, once economic stabilization hasbeen achieved, Asian and other developing countries would resume relativelyhigh rates of economic growth. This optimism will be moderated by the USeconomic slowdown that has already had severe knock-on effects in South-EastAsia, further compounded by the effects of the terrorist outrages in the USA.

The effects of such growth on the demand for livestock products and thusfor feed are, nevertheless, difficult to quantify. Income effects will vary fromcountry to country. In the developing countries, FAO studies indicate thatincome elasticities of demand can range from 0.4 in the case of some of themore traditional staple crops such as maize to +0.3 for high quality rice and,for a range of meats, from +0.2 to +0.9.

As livestock production becomes more commercialized in response to increasedconsumer demand, a major consideration will be the extent to which a particu-lar country can satisfy increased demand for feedstuffs on its own account andthe extent to which it will have to rely on imports.

Studies indicate that, in the developing countries, price elasticities of supply formost crops including those for livestock feed are, in general, fairly small (Huang etal., 1995). This implies that increased agricultural production to feed-growing popu-lations will depend on autonomous growth in areas cultivated and in the yield perhectare of cultivated land. A number of factors are relevant here, including publicand private research and development, conventional plant breeding, wide-crossingand hybridization breeding, biotechnology and the development of supportive infra-structure such as agricultural extension, markets and the availability of irrigation.

There is widespread agreement that the production increases that charac-terized the 1960s through to the early 1980s cannot be regarded as typical.This partly reflects the exhaustion of the Green Revolution effects but it alsoreflects other factors, notably the reduced availability of cultivable land andsome serious deficiencies in infrastructure investment, notably in irrigation.

6 R.W. Dean

SATISFYING INCREASED DEMAND FOR LIVESTOCKPRODUCTS THE INPUT REQUIREMENT


The area planted worldwide to wheat and coarse grains for the 2000/01harvest was 514 million hectares; 3.1% less than it was 30 years ago. Thisreflects diversion of land to other crops but it is also a by-product of the increas-ing urbanization of the planet, including the transfer of farm land to industrialactivity and the abandonment of many small-scale farming enterprises; aprocess which has not, especially in many developing countries, been accom-panied by sufficient investment in mechanized agriculture.

Final production in 2000/01 is projected at 1.44 billion tonnes; 49%greater than 30 years ago. This is due to increased yields per hectare, equiva-lent over the past three decades to almost 1.5% a year. While this may appearsatisfactory, it is a matter for major concern that the rolling 5-year % increasein cereal yields, as shown in Fig. 1.1, has been falling since the mid-to-late1980s. There are a number of reasons for this, which are specific to differentregions of the world. In the developed world, the decline in the growth ofcereal yields per hectare is primarily due to policy measures designed to drawdown cereal stocks and to substitute direct payments to farmers for farm-pricesupport programmes. In Eastern Europe and the former Soviet Union, eco-nomic collapse and subsequent economic reforms further depressed alreadylow productivity. In developing countries, particularly in Asia, the slow-downin cereal productivity growth has been a function partly of growing watershortages and of inadequate public investment, notably in irrigation infrastruc-ture. There is also, ominously, clear evidence of diminishing returns at work inthat ever-increasing use of fertilizers, water and other inputs are needed to sus-tain yield gains.


14

12

10

8

6

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0

Gro

wth

over

5 y

ears

(%)

1978/79 1983/84 1988/89 1993/94 1998/99 2001/02

8.39.7

12.9

8.7

6.24.6

Fig. 1.1. Five-year rolling yield increase for wheat and coarse grains.


These factors are expected to slow growth in cereal yields worldwide from1.6% a year in 19821997 to 1.0% a year in 19972020. This is a challengethat we are going to have to address in the next 20 years or so.

For 30 years, we have relied upon increased yields to provide the worldwith the wheat and other grains required to feed humans and livestock. Itneeds to be borne in mind, as one distinguished progenitor of the GreenRevolution has pointed out, that observers have tended to focus overly onhigh-yielding wheat and rice varieties as if they alone can produce the yieldimprovements noted during the 1970s and 1980s. Certainly, modern plantvarieties can uplift yield curves owing to their more efficient plant architectureand the incorporation of genetic sources of resistance to disease and insectinfestation. However, they can only achieve significantly improved yields overtraditional varieties if systematic changes in crop husbandry are made, such asin planting dates and rates, fertilizer application, water management, and weedand pest control. For example, higher soil fertility and greater moisture avail-ability for growing food crops also raises the potential for the development ofweeds, pests and disease. Complementary improvements in weed, disease andinsect control are thus also required to achieve maximum benefit.

If the potential of the Green Revolution is becoming played out for whateverreasons, we shall have to look to other means to provide world food and feedrequirements. The debate over transgenic crops is of clear relevance in this context.

The main engine driving the growth of demand for livestock feeds, and thusfeedstuffs use, worldwide in recent years has been the long expansion, duringthe 1980s, of livestock product consumption in East Asia and, most notably, inChina. This is not to exclude the effects of increased demand for livestockproducts in either the developed world or in Latin America and other emerg-ing economies.

Between 1994 and 1999, the consumption of poultrymeat rose by 11 mil-lion tonnes or by over 25%. Over half the additional consumption between1994 and 1999 took place in Asia where consumption has risen by almost 50%.

These data are remarkable in that they include the period in which theAsian economies were described, not without a degree of Western schaden-freude, as in a state of economic meltdown. China is, of course, the dominanteconomic entity of Asia. Consumption of poultrymeat in China grew by almost5 million tonnes or over 70% in the 5-year period. If we look at growth in poul-trymeat consumption over the period in question, it is evident that most of thisgrowth occurred in 19941996 before the regions economic difficulties of1997. For example, Chinese poultrymeat consumption in 1995 grew by 25%,and then fell progressively to 5% in 1998 and (forecast) 1999. Growth in theregion as a whole in 1995 was 18%; this fell progressively to 3% in 1998 andwas expected to be only 4% in 1999.

8 R.W. Dean

EMERGING PATTERNS OF LIVESTOCK CONSUMPTION


The role of economic growth in determining poultrymeat consumption is,of course, self-evident. In Brazil, consumption rose by almost a quarter in1995; in 1998, growth was only 2.5%, reflecting the effects of Brazils eco-nomic difficulties, but it bounced back in 1999.

Data subsequent to 1999 are not available on a basis that is consistent withthat shown in Table 1.1. The former suggests that poultrymeat consumptionworldwide rose by around 5.57 million tonnes or 10.5% between 1997 and2000. China recorded an estimated increase of 1.71 million tonnes or almost16%. Significantly, in the wake of the Asian economic meltdown in19971998, it was Brazil and Mexico that recorded increases in poultrymeatconsumption in excess of 30% between 1997 and 2000. Less dramatic but sig-nificant figures show Asia well in the lead in increasing pork consumption(USDA FAS, 1999). Out of the 6.2 million additional tonnes of pork consumedbetween 1994 and 1999, 95% was accounted for by Asian countries, largelyChina.

In considering the future development of feedstuffs use worldwide, we need tolook at a number of factors.

Primarily, the demand for feedstuffs will reflect demand for livestock prod-ucts. This will be a function, inter alia, of population and income growth and islikely to be greatest in the developing countries, notably those of China andSouth-East Asia. It cannot be stressed too highly that the development of live-stock product and thus feedstuffs demand is expected to show high rates ofvariation within the developing world. Most simulations suggest that growth insub-Saharan Africa and in the Indian subcontinent will be relatively slow.


Table 1.1. Global poultrymeat consumption by region 19941999.

Volume %change Change

1994 1995 1996 1997 1998 1999 199499 199499

Asia 11,215 13,242 14,678 15,646 16,140 16,805 5,590 50North America 14,259 14,385 14,848 15,145 15,574 16,502 2,243 16South America 4,196 4,937 4,757 5,227 5,375 5,515 1,319 31EU 6,829 6,993 7,406 7,412 7,588 7,754 925 14Middle East 1,178 1,270 1,385 1,598 1,674 1,743 565 48Africa 1,078 1,193 1,251 1,346 1,416 1,511 433 40Eastern Europe 811 810 872 935 987 1,004 193 24Oceania 489 490 493 522 569 586 97 20Former Soviet Union 2,002 1,968 2,008 2,099 1,737 1,564 438 22Total 42,057 45,288 47,698 49,930 51,060 52,984 10,927 26

Source: FAS post reports, official statistics, and inter-agency analysis.

FUTURE AGRONOMIC INFLUENCES ON FEEDSTUFFSPRODUCTION SUMMARY


The extent to which feedstuffs production and usage in the developing worldincreases will depend on competition for the available resources of land, labourand capital. It is, for example, suggested that where land is the main constraint,farmers may prefer to concentrate on high-value crops for fast-growing urban mar-kets rather than on feedstuffs production. While production of livestock is expectedto increase in the developing world, it is questionable whether they will producerequisite feedstuffs themselves or import them. Certainly, most recent studies sug-gest a substantial net increase in developing countries net imports both of live-stock products and feedstuffs during the first quarter of the 21st century.

The extent to which yield growth for most cereals has declined in recentyears is of concern because of the pressures being exerted on cultivable land.Again, this stresses the combined effect of industrial encroachment and inade-quate investment in infrastructure and irrigation.

In this section of the chapter, the background to consumption of feedstuffs isdiscussed with particular reference to the consumption of livestock products.

A very generalized form of analysis defined consumption of any product asfollows:

Consumption = Income, Price, Underlying Demand, Dummy Variable, ErrorC (1..n) f (Y (1..n),P (1..n),Du (1..n),Vd (1..n), (1..n))

In a collection of papers marking the 50th anniversary of the NationalFood Survey, one contributor suggests that each of these variables has in turndominated the consumption of livestock products since the end of the SecondWorld War. Ritson and Hutchins (1991) suggested that post-war food con-sumption in Britain could be divided into five phases to which the presentauthor would add a sixth. These are as follows, and are applicable in generalterms to all developed European economies but not to the USA.

19511960 Return to normal dietsWith the end of rationing in 1951 and the availability of more plentiful suppliesof food, consumers were enabled to return to what would have been regardedas a more normal pattern of consumption, given the constraints of prevailingincomes and prices.

19601970 Income-driven demandIncreasing consumption of livestock products reflected rising real disposableconsumer income. As people felt wealthier, they felt freer to trade up to moreexpensive products or to consume more of existing products. This period canbe summed up in Harold Macmillans immortal political slogan for the General

10 R.W. Dean

CONSUMER POWER

The Use of Statistical Method in the Analysis of Consumption


Election of 1959; Youve Never Had It So Good. Consumption of some moretraditional food products such as canned meats and sausages declined, whilethat of fresh meat and poultry as well as cheese increased.

19701980 PriceThe 1970s were a disturbed period in post-war UK history. The UK joined theEU in 1973 and this required a 5-year period of transition to higher EU farmprices, including those for livestock products. The oil-shock of 1973 caused aperiod of rapidly rising world commodity prices. In addition, this was a periodof considerable social unrest, epitomized by the 3-day week following the startof the miners strike and the two General Elections of 1974; the first fought onthe basis of Who Governs Britain.

19801990 Underlying demand and dummy variablesThe Lawson boom of the late 1980s created new patterns of consumption; oflivestock products no less than of Porsches and designer clothing. Part of thiscan be described as lifestyle, such as the abandonment of the family lunch onSunday and the increased incidence of convenience food and takeaway eating.A spin-off of the lifestyle effect has been the increasing consumer concern withhealthy eating. This has impacted on milk and butter consumption while ben-efiting poultry consumption at the expense of the red meats. Dummy variables,used to represent discrete events such as the Salmonella crisis in 1988, the leadcontamination problem that affected dairy feeds in 1989 and the ongoing BSEcrisis that rumbled on through much of 19891990, finally breaking in full furyin 1996, assume much greater importance during this period.

Post 1990 The collapse of consumer confidenceThere can be little doubt that, in the UK and in Western Europe in general,consumer confidence in the food they eat has been eroded by succeeding foodscares and a remarkable degree of ineptitude on the part of governments inthe management of those scares.

Only if it is argued that governments are constitutionally incapable of learn-ing from past mistakes, are the actions of the Belgian government over thedioxin scandal comprehensible. In the UK, the BSE crisis undermined morethan consumer confidence in beef. The jury may still be said to be out on thequestion of who, if anyone, was to blame but, in recent comments about gov-ernment trustworthiness over GM foods, the BSE saga is often quoted by theopponents of GM technology to illustrate the non-credibility of the governmentand thus, by extension, the credibility of the lobby groups.

It has been a long-standing principle on the part of the feedstuffs industrythat science and scientific method should determine how feedstuffs are usedto feed poultry as in any other form of livestock production. It cannot, how-ever, be assumed that this principle will, in future, be accepted by consumersor, at least, by their self-appointed guardians in the consumer and environ-mental movements.

It must be noted, none the less, that two recent controversies, one non-food related and the other definitively so, have been sparked off by allegedly



scientific evidence which has been used by organizations to create alarm whichhas been enthusiastically taken up by the media. The Brent Spar oil platformcontroversy pursued by Greenpeace was based on quite erroneous evidence asto the amount of pollution that would ensue should the platform be sunk, asoriginally intended, in deep Atlantic waters. Greenpeace subsequently apolo-gized to Shell Oil for their misrepresentation of the facts a fact studiouslyignored by most of the media on the grounds that it is the height of politicalincorrectness to attack Greenpeace but the damage was done.

The debate over genetically modified organisms (GMOs) is, potentially,much more critical not just to the feedstuffs industry but to science in general.

The GM controversy it cannot surely be called a debate initiated by thepublication of a letter supporting the cause of Dr Arpad Pusztai of the RowettResearch Institute, whose work on the effects of GM potatoes, genetically modi-fied to express a lectin originating in the snowdrop, on the gut of rats hasachieved a certain notoriety. Again, reputable bodies, including the RoyalSociety, have questioned the scientific basis of this work. No matter. This harehas been set running and the feed industry and the livestock industry must facethe unpalatable fact that further factors have entered the Research andDevelopment equation.

The first is the emergence into positions of prominence of organizationswhose belief in the moral rightness of their cause and it is a moral rightnessbecause no scientific consideration is involved is comparable with the self-righteousness of a 17th-century Witchfinder-General or the Dominican-inspiredInquisition. Governments are in the position, increasingly, of having to defer tosuch organizations. Brussels immediate reaction, for example, to the dioxinscandal was to announce plans to review the list of permitted ingredients andthe schedule of undesirable substances in feedstuffs. Since dioxins are not, as faras the author is aware, a permitted ingredient in feedstuffs, this response seemsless than relevant. However, it leads to a much more significant general point.

Over the past decade, three controversies have afflicted the livestock indus-try. These references do not include sporadic outbreaks of Salmonella, E. coli0157, Campylobacter and Listeria.

For more than a decade, a debate has raged over hormone-based growthpromoters in beef production, largely as a result of a trade dispute with theUSA that permits the use of such substances. Most scientific evidence tends tosupport the view that, properly used, such substances pose no danger to eitherbeef cattle or to human consumers of beef.

Bovine somatotrophin therapy in milk production has been licensed in theUSA. This is a biotechnology product that significantly increases milk produc-tion. Welfare issues have been raised about its effect on dairy cows; the role ofIGF-1 on human health remains controversial.

The latest controversy over GM foods affects the feedstuffs industry in thattwo important raw materials used by the feed industry, maize and soybeans,are directly affected.

Setting aside, for the moment, the biotechnology-related aspects of bovinesomatotrophin and GM crops, these three areas of dispute are linked by onecommon factor. The products are science-generated and the body of fact avail-

12 R.W. Dean


able to us supports the argument for their use at the present time. This does notmean that we should close the books on further evaluation. Increasingly com-plex scientific and technical solutions to the problems of the livestock and feed-stuffs industry will require increasingly complex review procedures. What is alsoclear, however, is that a political input will also be required and that the feed-stuffs industry, increasingly science-based, needs to improve the presentation ofits case. Whether this will be successful is questionable. One aspect of thedebate is, however, eminently arguable. It is said that We do not need theseGM crops. Whether this is so or not, it requires an answer to the question howare we going to meet the demand for crops to satisfy both human food andlivestock feed demand?. It would be much easier for everyone concerned ifthis were a purely agronomic question. Politics is, however, now firmlyentrenched in the debate and that is something that the livestock industry andits feedstuffs suppliers will fail to address to its own profound disadvantage.

Bouis, H. (1994) Changing food consumption patterns in Asia and prospects forimprovements in nutrition: Implications for Agricultural Production. Paper pre-sented at a symposium sponsored by the Asian Productivity Organisation onChanging Dietary Intake and Food Consumption.

Huang, J., Rosegrant, M.W. and Rozelle, S. (1995) Public Investment, TechnologicalChange and Reform: a Comprehensive Accounting of Chinese Agricultural Growth.International Food Policy Research Institute, Washington, DC.

Pindstrup-Andersen (1992) Global perspectives for food production and consumption.Tidsskrift for Land Okonomi 4, 145169.

Ritson, C. and Hutchins, R. (1991) The consumption revolution. In: Fifty Years of theNational Food Survey 19401990. HMSO, London.

Rosegrant, M.W., Agcaoili-Sombilla, M. and Perez, N.D. (1995) In: Global FoodProjections to 2020: Implications for Investment. International Food PolicyResearch Institute, Washington, DC.

USDA FAS (2001) World Production, Consumption and Trade in Grain (October 2001update).


REFERENCES


Poultry_Feedstuffs_Supply_Composition_and_Nutritive_Value/Poultry Feedstuffs Supply Composition and Nutritive Value/0851994644Ch10.pdfCHAPTER 10The availability of calcium andphosphorus in feedstuffs

C. Coon, K. Leske and S. SeoDepartment of Poultry Science, University of Arkansas, Fayetteville, AR72701, USA

CAB International 2002. Poultry Feedstuffs: Supply, Composition and Nutritive Value(eds J.M. McNab and K.N. Boorman) 151

In a review describing different calcium and phosphorus sources utilized forfeed formulations, Waldroup (1996) reported that although 12 minerals areconsidered essential minerals for poultry and pigs, meeting the calcium andphosphorus needs of these animals is of the greatest concern to nutritionistsand producers. This concern is warranted due to the relative quantitiesneeded and due to the adverse effects on the animals that occur when inade-quate dietary levels are fed. Producers need to make informed decisionsbased on animal health, production and economics as to how they will meetthe needs of the animals, especially in the case of phosphorus, which is rela-tively expensive compared with calcium. The quality of calcium and phospho-rus sources is important in that the availability of the sources used willdetermine the quantity that is required in the diet and the amount that will bein the manure of the animals. This latter point is becoming of greater impor-tance as evidence indicates that phosphorus from manure has a negativeeffect on water quality. Because of the relatively high cost of adding phospho-rus to diets, there has been a large amount of research dedicated to determin-ing the necessary dietary levels and quality of phosphorus sources in poultrydiets. In contrast, calcium is typically inexpensive compared with phosphorusand at present poses no ecological concern, consequently there has been lessemphasis placed on calcium requirement (with the exception of shell quality oflaying hens) and source quality research.

Calcium and phosphorus are the two most abundant minerals found inthe body, due mainly to their major involvement in bone formation.Calcium and phosphorus are also necessary for efficient feed utilization andweight gain. Calcium is essential to the formation of eggshell and is requiredfor the formation of blood clots, muscle contraction and transmission ofnerve impulses. Calcium is also involved in the regulation of heartbeat, canact as an activator or stabilizer of enzymes and is involved in hormonesecretion. Phosphorus is needed for normal muscle growth and egg forma-tion, is a component of the nucleic acids of the genetic code, and of phos-pholipids, and is also a component or activator of a large number of enzymesystems. Phosphorus aids in maintaining osmotic and acid-base balance, isa factor in energy metabolism (ATP), amino acid metabolism and protein

Poultry Chapter 10 29/5/02 2:04 PM Page 151

production. Lack of adequate dietary calcium and phosphorus in growingpoultry leads to abnormal calcification of bones, known as rickets. Visiblesymptoms of rickets are swollen joints, enlargement of end bones and rub-bery beaks and may be the result of inadequate calcium, phosphorus or vit-amin D in the diet of the bird. Older birds subjected to inadequate dietarycalcium and phosphorus develop brittle and weak bones (osteomalacia). Inlaying hens, calcium deficiency first manifests itself as thin and weak egg-shells. A prolonged and severe lack of dietary calcium can lead to a com-plete cessation of egg production.

Calcium and phosphorus can be provided in poultry diets by a large num-ber of sources. A portion of diet calcium and phosphorus content is provided bythe plant feedstuffs used to provide dietary energy and protein. Table 10.1shows a list of plant feedstuffs and their calcium and phosphorus contents.Typically, a large proportion of plant feedstuffs phosphorus is in the form ofphytate phosphorus, which is not highly available to the bird. Since plant feed-stuff components of poultry diets generally do not provide enough of these min-erals to meet the needs of maintenance, growth and production, diets aretypically supplemented with concentrated calcium and phosphorus sources.Sources of calcium and phosphorus are listed in Table 10.2. Limestone and oys-ter shell are the more commonly used sources of calcium for poultry diets, asthey are relatively inexpensive. A larger variety of phosphorus sources exist.Natural, unprocessed phosphorus sources tend to have lower and more variablephosphorus contents than the higher priced, chemically processed phosphates.Selection of calcium and phosphorus sources to use to supplement diets is basedon local availability and price.

Van der Klis (1993) has provided an extensive review of calcium and phospho-rus absorption and excretion by poultry. Table 10.3 lists the sites of absorptionand excretion for both calcium and phosphorus in poultry. Hurwitz and Bar(1969, 1970) observed net secretion in the duodenum of broilers but netabsorption in the duodenum of laying hens. Most calcium absorption has beenfound to occur in the duodenum and jejunum in broilers and layers (Hurwitzand Bar, 1970, 1971; van der Klis et al., 1990). In laying hens, absorption hasalso been observed in the lower gastrointestinal tract. The secretion andabsorption of calcium by different intestinal segments in laying hens has beenfound to be dependent on the stage of eggshell formation (Hurwitz and Bar,1965; Nys and Mongin, 1980; Waddington et al., 1989). Calcium is trans-ported across the intestinal membranes by a saturable, active (transcellular)process and a non-saturable (paracellular) process. The saturable (active)process can be affected by the nutritional and physiological status of the bird(van der Klis, 1993). During calcium restriction, active transport is significantlyincreased (Hurwitz and Bar, 1969; Hurwitz, 1989). Excretion of calcium fromthe cell has been described as an active process (Wasserman et al., 1992).

152 C. Coon et al.

ABSORPTION AND EXCRETION OF CALCIUM ANDPHOSPHORUS


The absorption of phosphorus by the gastrointestinal tract has been foundto be similar to, but not dependent on the absorption of calcium (Wasserman,1981). Absorption of phosphorus in broilers was determined to be most effi-cient from the duodenum to the upper jejunum (Hurwitz and Bar, 1970), withno net absorption occurring in the lower gastrointestinal tract. Layers havebeen shown to absorb phosphorus throughout the whole intestine, but the rateof absorption declines in the lower tract. Large amounts of endogenous phos-phorus have been shown to be secreted into the duodenum of laying hens(Hurwitz and Bar, 1965). As is the case with calcium, laying hens show differ-ences in phosphorus absorption and excretion based on stage of eggshell for-mation. Wasserman and Taylor (1973) suggested that the absorption ofphosphorus is a saturable, active process. Favus (1992) described a cotrans-port system for sodium and phosphorus to effect the movement of phospho-rus into the cell and identified facilitated diffusion as a means of phosphorusleaving the cell.

Availability of calcium and phosphorus in feedstuffs 153

Table 10.1. Calcium and phosphorus content of common plant feedstuffs (National ResearchCouncil, 1994).

Total Non-phytate Non-phytateCalcium phosphorus phosphorus phosphorus

Feedstuffs content (%) content (%) content (%) (% of total phosphorus)

Lucerne meal, 17% CP 1.44 0.22 0.22 100.0Barley 0.03 0.36 0.17 47.2Buckwheat 0.09 0.32 0.12 37.5Canola meal, 38% CP 0.68 1.17 0.30 25.6Maize gluten meal, 60% CP 0.50 0.14 28.0Maize, grain 0.02 0.28 0.08 28.5Cottonseed meal, 41% CP 0.15 0.97 0.22 22.6Distillers dried grains 0.10 0.40 0.39 97.5Distillers dried solubles 0.35 1.27 1.17 92.1Oats, grain 0.06 0.27 0.05 18.5Groundnut meal 0.20 0.63 0.13 20.6Pearl millet 0.05 0.32 0.12 37.5Rice bran 0.07 1.50 0.22 14.7Rice polishings 0.05 1.31 0.14 10.7Rye, grain 0.06 0.32 0.06 18.8Safflower meal, 43% CP 0.35 1.29 0.39 30.2Sesame meal, 43% CP 1.99 1.37 0.34 24.8Soybean meal, 44% CP 0.29 0.65 0.27 41.5Soybean meal, 48% CP 0.27 0.62 0.22 35.4Soy protein concentrate 0.02 0.80 0.32 40.0Sunflower meal, 45% CP 0.37 1.00 0.16 16.0Wheat bran 0.14 1.15 0.20 17.4Wheat middlings 0.12 0.85 0.30 35.3Wheat, hard winter 0.05 0.37 0.13 32.0


Factors which may affect gastrointestinal absorption of calcium and phos-phorus include dietary concentration and physical and chemical forms of theseminerals, passage rate of feed and viscosity of digesta, chelating agents andmineral interactions, gastrointestinal tract pH, and interactions with dietary pro-tein, fat and carbohydrate (van der Klis, 1993).

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Table 10.2. Common sources of calcium and phosphorus (Waldroup, 1996).

Source % Ca % P

Limestone 38 Oyster shell 38 I. Calcium phosphates

A. Natural or unprocessedLow fluorine rock phosphate 3235 1215Curacao phosphate (guano) 36 1315Colloidal phosphate (soft phosphate) 1820 910Bone meal, steamed 2326 818

B. Chemically processed1. Dicalcium phosphates

Di/mono calcium phosphates 1523 1823Mono/dicalcium phosphates 1518 2021Precipitated dicalcium phosphates 2426 1822

2. Defluorinated phosphates 3036 1418II. Sodium phosphates

Monosodium phosphate 25Disodium phosphate 21Sodium tripolyphosphate 25

III. Ammonium phosphatesMonoammonium phosphate 24Diammonium phosphate 20

IV. Phosphoric acid 2324Fish meals 214 27Meat and bone meals 414 210Poultry by-product meals 210 28

Table 10.3. Sites of calcium and phosphorus absorp-tion or secretion in broilers (van der Klis, 1993).

Site Calcium Phosphorus

Duodenum Secretion SecretionUpper jejunum Absorption AbsorptionLower jejunum Absorption AbsorptionUpper ileum Absorption No changeLower ileum No change No change


The reason retention of minerals has more meaning than digestibility or avail-ability of minerals is because the kidney plays an important role in the amountof mineral that will be retained or found in the excreta. In order to determinethe digestibility or availability of minerals for a feedstuff, the separation of theurinary minerals from the faecal minerals is necessary.

Calcium and phosphorus content of poultry urine is determined by therates of kidney secretion and reabsorption of the minerals. The quantity ofcalcium and phosphorus excreted by the urine is thus dependent on glomeru-lar filtration rates, tubular reabsorption rates and tubular secretion rates.Factors affecting kidney excretion of calcium and phosphorus are listed inTable 10.4. Wideman (1984) noted that blood or plasma inorganic phospho-rus concentrations had only an indirect influence on the amount of phospho-rus secreted by the kidney and that only a small fraction of secreted urinaryphosphorus was composed of organic phosphates. Wideman (1987) sug-gested that calcium availability for eggshell formation was the controllingparameter for laying hen urinary calcium and phosphorus excretion patterns.The author noted that urinary phosphorus excretion increased and urinarycalcium excretion decreased when bone minerals are mobilized for eggshellformation. Another major determinant of urinary phosphorus excretion isparathyroid hormone, which inhibits tubular reabsorption of inorganic phos-phorus. Both high dietary calcium and low dietary phosphorus have beenshown to depress urinary phosphorus excretion. A high calcium, low phos-phorus diet resulted in very high urinary calcium excretion (Wideman, 1987).Increased dietary phosphorus leads to increased kidney phosphorus excre-tion, whereas low dietary phosphorus stimulates phosphorus reabsorption bythe kidneys (Wideman, 1989).

Total excreta calcium and phosphorus content then is the summation ofunabsorbed gastrointestinal ingested and secreted calcium and phosphorusfrom the gastrointestinal tract plus urinary calcium and phosphorus. Thedietary and physiological factors affecting the digestibility, absorption andsecretion of minerals in the gastrointestinal tract, along with factors affectingthe excretion of calcium and phosphorus in the urine, will need to be takeninto consideration.


URINARY EXCRETION OF CALCIUM AND PHOSPHORUS

Table 10.4. Factors that affect avian urinarycalcium and phosphorus (Wideman, 1987).

Parathyroid hormoneDietary calcium and phosphorus levelsVitamin DStage of eggshell formationCalcitonin ?


Sullivan and Douglas (1990) published an excellent review of phosphorus bioas-says performed from 1945 to 1990, wherein they traced the development of rel-ative biological value bioassays and discussed the primary variable which canaffect the data obtained from such studies. Dietary phosphate sources havebeen primarily evaluated for poultry with 23 week feeding trials. The biologicalvalue of a phosphorus source is determined by feeding chicks or poults differentamounts of the test phosphates in a phosphorus-deficient diet for a 23 weekperiod and comparing the weight gain, feed conversion, proportion of tibia ash,or other performance parameter with a phosphorus source designated to be astandard phosphate (usually a food reagent grade phosphorus source). Thestandard phosphate used is assigned a biological value of 100 (for 100% avail-able), and the feedstuff phosphates assigned relative biological values comparedwith the biological value of the standard phosphorus source. Numerous refer-ence standards have been employed, including potassium phosphates, sodiumphosphate, and mono-, di- and tri-calcium phosphates. Both conventional andpurified diets have been used in these types of assays. Though useful in qualita-tively comparing different phosphorus sources, these studies are limited in thatthey provide only values relative to the standard chosen and other factors (Table10.5), such as selection of response criteria, also may play a role in determiningthe value assigned to a phosphorus source. These bioassays provide phospho-rus bioavailability data and response criteria specific to a chosen standard butlack the ability to provide actual data needed to determine available, digestibleor retainable phosphorus in a feedstuff for poultry.

Compared with the large amount of research conducted on biological val-ues of phosphorus sources, little research has been done in this manner tocompare calcium sources. Dilworth et al. (1964) determined relative availabili-ties of four feed-grade calcium sources for starter period chicks, utilizing a USPgrade calcium carbonate as the standard. The authors determined that defluo-rinated phosphates resulted in high relative calcium availability based onweight gain and tibia ash compared with a low fluorine rock phosphate and asoft phosphate (Table 10.6). Spandorf and Leong (1965) found the biological

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EVALUATION OF CALCIUM AND PHOSPHORUS AVAILABILITY INFEED INGREDIENTS

Traditional Biological Value Assays

Table 10.5. Factors affecting phosphorusrelative bioavailability bioassays (Sullivan andDouglas, 1990).

1. Selection of response criteria2. Reference of standard phosphate selected3. Diet composition purified or practical4. Ca:P ratio5. Species and type of fowl6. Bioassay length


availability of calcium in 12 menhaden fish meals to be similar to that of cal-cium in limestone and dicalcium phosphate. Reid and Weber (1976) reportedthat bioavailability of feed-grade calcium sources ranged from 73.3% to109.4% compared with a reagent-grade calcium carbonate. Calcium availabil-ity can be dependent on the particle size of the source, especially at marginaldietary levels. Hillman et al. (1976) reported that small particle-size limestoneresulted in increased weight gain, feed efficiency and calcium availability tothe turkey poult at low dietary calcium levels. This effect of small particle sizehas also been shown with male broiler chicks (Guinotte and Nys, 1991a).These same authors and others (Cheng and Coon, 1990; Rao and Roland,1990; Guinotte and Nys, 1991b) have noted that the converse is true in layinghens; large particle size calcium sources result in improved bone ossification,eggshell quality and performance. It has been suggested that the increasedavailability for laying hens of larger particle size sources is the result of aslower rate of passage through the digestive tract of the hen, allowing absorp-tion when needed for eggshell formation (Zhang and Coon, 1997). The parti-cle size needs a minimum diameter of 0.91.0 mm to be retained in thegizzard for more efficient utilization during the time of eggshell formation. Theavailability and performance differences, due to particle size of calciumsources, have been most evident when the hens daily intake of calcium ismarginal to deficient. Anderson et al. (1984) observed that chicks can passexcess calcium of medium particle size through the digestive tract more rapidlythan small particle size calcium sources. The faster passage rate of the mediumsize particles for broilers may limit overall calcium utilization. McNaughton(1981) reported that particle size of the calcium source could also affect phos-phorus utilization in the chick.

The nutritionist today needs an actual biological retention value for key miner-als to assess the true impact of dietary formulations on animal performanceand on the elements remaining in animal waste, which will potentially affectthe ecological system. The relative biological availability assays for calciumand phosphorus provide a valuable tool for comparing the feeding value ofdifferent sources of calcium and phosphorus. The information obtained from a


Table 10.6. Calcium availability of feed-grade phosphates(Dilworth et al., 1964).

Calcium source Relative availability (%)

CaCO3 USP 100Low fluorine rock phosphate 90Defluorinated phosphate A 95Defluorinated phosphate B 92Soft phosphate 68

RETAINABLE CALCIUM AND PHOSPHORUS


relative biological availability assay has limited value for a nutritionist formu-lating diets. The relative biological value is dependent on a standard which isassumed to be of higher availability than the other sources being evaluatedand is dependent on a performance response criterion rather than on actualmineral retained and excreted. The calcium or phosphorus source used as astandard may not be 100% available, so the availability obtained for the min-eral for a test ingredient has limited value. Retention bioassays measure bothingested and excreted calcium and phosphorus and would provide the meansto calculate actual mineral retained. The ability to detect changes in calciumand phosphorus retention will provide important information needed to assessthe economic value of increasing dietary concentrations of these key mineralsand also to evaluate the effect of adjusting other nutrients on calcium andphosphorus utilization. Retention is defined herein as the amount of ingestedmineral (calcium or phosphorus) that is not excreted. In the case of phospho-rus, retainable phosphorus can include that from both non-phytate and phy-tate sources assessed with a balance method using a Celite marker as reportedby Gueguen (1996). Thus:

Total phosphorus retained = non-phytate phosphorus retained + phytate phosphorus retained

Phosphorus retention (%) = (total phosphorus ingested total phosphorus excreted)/total phosphorus ingested) 100

Excreted mineral as a proportion of ingested mineral can be determinedeither by the total collection technique or by the use of an indigestiblemarker. The above equation can also be used to determine retention of cal-cium. Although many authors use the terms available or digestible to refer tothe above calculation, here we will use the term retainable in order to differ-entiate from the relative biological availability studies. Also, non-phytatephosphorus and available phosphorus are often inaccurately used inter-changeably, although studies have shown that non-phytate phosphorus is not100% available and phytate phosphorus is not 100% unavailable. Theterm digestibility, often used to describe the utilization of amino acids, is alsoless descriptive than would be desired, as it is a term for describing the disap-pearance of a nutrient from the gastrointestinal tract, but does not accountfor the excreta calcium and phosphorus from the urine. For the sake of clarityin the following discussion, data from authors calculated according to theequations above will be referred to as retained, rather than available ordigestible as in the original publication.

Retention bioassays can provide requirement information based on theactual amount of calcium and phosphorus retained, rather than the amountfed. This allows for a determination of a requirement irrespective of sourcequality and provides a tool for predicting the amount of a mineral that willbe present in the excreta. Retention bioassays also can provide informationon the availability of calcium and phosphorus in plant feedstuffs, includingphytate phosphorus. Determination of requirements based on retention ofminerals is based on the concept put forth by Sibbald (1982) and illustratedin Fig. 10.1.

158 C. Coon et al.


Commercial egg layers and pulletsHurwitz and Griminger (1962) determined calcium retention of laying hens (atproduction rates of 0.7 eggs per bird day or more) using synthetic diets withdiffering rates of calcium supplementation and total excreta collection. Theauthors determined calcium retention to be approximately 5055% when thebirds were in calcium balance and optimum shell thickness was obtained (3 gday1). At higher daily intakes of calcium, percentage retention of calciumdecreased. Rao and Brahmakshatriya (1976) fed pullets at three calcium con-centrations and determined calcium retention at 18, 21 and 24 weeks of ageusing a total collection method. They observed that at 18 weeks of age, cal-cium retention was increased for the higher calcium diets (Table 10.7).However, at 21 and 24 weeks of age, although net retention increased, per-centage calcium retention decreased with increasing dietary calcium. Keshavarz(1986) reported similar results based on total collection with laying hens fed ona basal diet containing maize and soybean meal. The author noted that as cal-cium concentration increased, net calcium retained increased although percent-age retention of calcium and phosphorus decreased (Table 10.8). Phosphorusretention decreased as phosphorus intake increased. Dietary phosphorus hadno impact on calcium retention. Scott and Balnave (1991) used acid-insolubleash as a marker and observed that calcium retention for sexually maturing pul-lets was affected by age, temperature and metabolizable energy content of thediet. Nahashon et al. (1994), using a chromic oxide as a marker, determinedthe calcium and phosphorus retentions from maize and soybean meal diet forlaying pullets to be 58.9% and 24.4%, respectively. They noted that an addi-tion of fat (10 g kg1) increased calcium and phosphorus retention from thediet, but more fat addition (30 g kg1) produced no further benefits.


0 5 10 15 20 25 30

Calcium input

0

5

10

15

20

25Ca

lcium

voi

ded

% bioavailable

100

75

50

30

A Requirement = A + B

B

Fig. 10.1. Theoretical response of excreted calcium at different intakes and source quality(Sibbald, 1982).

Retention Assays


BroilersA large portion of the data on calcium and phosphorus retention by broilershas been in conjunction with research on the utilization of phytate phospho-rus and the effects of an added phytase enzyme. Two excellent reviews onphytate and the use of microbial phytase in poultry diets have been providedby Ravindran et al. (1995) and Sebastian et al. (1998). Factors affectingretention of phytate phosphorus are similar to those affecting retention ofphosphorus in general. Sebastian et al. (1998) listed the following as factorsaffecting phytate phosphorus utilization: dietary calcium and phosphorusconcentration, dietary vitamin D3 concentration, age of bird, phytase activityof dietary ingredients, fibre and genotype. Qian et al. (1997) used a total col-lection method to determine the calcium and phosphorus retention frommaize and soybean meal diets by 21-day-old male broilers. The authorsdetermined calcium retention to range between 42% and 67%, depending onthe calcium : total phosphorus ratio, the addition of 66 or 666 g kg1 dietvitamin D3, and the addition of 0900 phytase units kg

1 diet. Phosphorusretention from the diets ranged from 51 to 68%, depending on the same fac-tors. The addition of vitamin D3 increased phosphorus and calcium reten-tions, as did the addition of phytase. This agrees with earlier findings of

160 C. Coon et al.

Table 10.7. Calcium retention in pullets (Rao and Brahmakshatriya, 1976).

Diet calcium % calcium retention

(%) 18 weeks 21 weeks 24 weeks

1.05 33.33 32.91 40.902.20 48.46 26.99 37.693.30 39.90 21.57 37.56% Total P = 0.72%

Table 10.8. Retention of calcium and phosphorus by laying hens at 69 weeks of age (Keshavarz, 1986).

Diet calcium Calcium intake Calcium retention Phosphorus intake Phosphorus retention(%) (g day1) (%) (g day1) (%)

3.50 3.48c 49.8a 0.74a 31.3a

4.50 4.50b 44.9ab 0.75a 25.4b

5.50 5.42a 39.1b 0.68b 20.2b

Diet non-phytate P%0.24 4.25b 46.2a 0.54c 30.5a

0.44 4.64a 45.8a 0.75b 25.3ab

0.64 4.51a 41.8a 0.88a 21.2b

Ca P interaction P < 0.05 NS P < 0.05 P < 0.05

a,b,cMeans followed by different letters in each column under calcium and phosphorus levels are signifi-cantly different (P < 0.05).


Mitchell and Edwards (1996). Calcium and phosphorus retentions were bothincreased as the calcium : total phosphorus ratio was reduced from 2.0 : 1 to1.1 : 1. Simons et al. (1992) have estimated that the addition of phytase to amaize and soybean meal diet can lower the need for monocalcium phos-phate supplementation of broiler diets by 1 g kg1. Mitchell and Edwards(1996) found that the addition of 5 g of 1,25-(OH)2 vitamin D3 and 600units phytase kg1 broiler diet can reduce the amount of supplemental phos-phorus needed by 2 g kg1.

FeedstuffsLittle research has been reported on the calcium and phosphorus retention fromindividual feedstuffs. Van der Klis and Versteegh (1999) measured the retentionof phosphorus by 3-week-old male broilers from a large number of feedstuffs(Table 10.9). They utilized a total collection method and a synthetic diet in whichthe test feedstuff provided most of the phosphorus. Diets were standardized


Table 10.9. Phosphorus content and retention of feedstuffs (van der Klis and Versteegh, 1999).

Total P content Retainable phosphorus(%) (% of total phosphorus)

Plant feedstuffsBeans 0.49 52Lupin 0.30 72Maize 0.30 29Maize gluten feed 0.90 52Maize feed meal 0.51 50Peas 0.41 41Rape seed 1.09 33Rice bran 1.72 16Soybean (heat treated) 0.55 54Soybean meal (solvent extracted) 0.71 61Sunflower seed (solvent extracted) 1.19 38Tapioca 0.09 66Wheat 0.34 48Wheat middlings 1.08 36

Animal feedstuffsBone meal 7.6 59Fish meal 2.2 74Meat meal 29 65Meat and bone meal 60 66

Feed phosphatesCalcium sodium phosphate 18.0 59Dicalcium phosphate (anhydrous) 19.7 55Dicalcium phosphate (hydrous) 18.1 77Monocalcium phosphate 22.6 84Mono-dicalcium phosphate (hydrous) 21.3 79Monosodium phosphate 22.4 92


with the test ingredient to contain 18 g calculated kg1 retainable phosphorusand all diets contained 5 g kg1 calcium. Leske and Coon (1999) determinedthe calcium and phosphorus retentions from various plant feedstuffs with broil-ers and laying hens. They used synthetic diets in which the test feedstuff was theonly source of phosphorus. Diets were offered to the birds with or without addedphytase. The data (Tables 10.10 and 10.11) indicated that the dietary ingredi-ents used influenced phytate phosphorus hydrolysis and total phosphorus reten-tion for both broilers and layers. The effect of phytase supplementation onphosphorus retention was also dependent on ingredient. The addition of phy-tase increased calcium retention from maize and soybean meal in broilers.

Five day bioassayLeske and Coon (2001) conducted a retention bioassay to determine thetotal phosphorus retention of a reagent grade monocalcium phosphate (MCP;J.T. Baker, Phillipsburg, NJ 08865, USA, product 426-05) and three com-mercially available feedgrade mono- and dicalcium phosphates (M/DCP).Male broiler chicks were offered a standard starter diet until 10 days of age(240 g mean body weight). Eighty-eight chicks of mean body weight 13 gwere then placed in individual cages and offered 20 semi-synthetic test diets(four chicks per diet), in which the majority of the phosphorus came from thetest source. Phosphorus concentration was adjusted by replacing cellulosewith eight concentrations of the MCP, and four concentrations each of thecommercially available phosphorus sources. CeliteTM (Celite Corp., Lompoc,

162 C. Coon et al.

Table 10.10. Hydrolysis of inositol hexaphosphate and calcium and total phosphorus retention by 3-week-old broilers of seven feed ingredients with or without 600 FTU phytase as determined with a 2-dayexcreta collection (Leske and Coon, 1999).

Feed ingredient Phytase n Calcium retention Hydrolysis of IP6 Total P retention

% % %Soybean meal 9 69.8fgh 34.9b,wx 27.0b,y

Soybean meal + 8 87.2a 72.4a,h 58.0a,h

Maize 9 64.0ghi 30.8b,wx 34.8b,wx

Maize + 10 72.8def 59.0a,i 40.9a,i

Rice bran 10 33.3j 33.2b,wx 15.5b,z

Rice bran + 9 62.0hi 48.0ajk 26.5a,k

Canola meal 10 70.5defg 36.7b,w 39.4a,w

Canola meal + 10 73.4def 55.8a,ij 45.7a,i

Barley 8 78.6bcd 32.2b,wx 40.3b,w

Barley + 8 85.6ab 71.3a,h 55.5a,h

Wheat middlings 8 74.8cdef 29.1b,x 31.9b,xy

Wheat middlings + 8 78.3bcde 52.2a,ijk 43.4a,i

a,bHydrolysis of IP6 and total P retention, means within a specific feed ingredient treatment and columnwith differing superscripts are significantly different (P 0.05).h,i,j,kHydrolysis of IP6 and total P retention, means within the added phytase (+) treatment and samecolumn with differing superscripts are significantly different (P 0.05).w,x,y,zMeans within the no added phytase () treatment and same column with differing superscripts aresignificantly different (P 0.05).


CA 93436, USA) was added to the diets as an acid-insoluble ash marker.Broilers were acclimatized to cages and test diets for 3 days prior to initiationof experiment. Individual stainless steel trays were placed under each cagefor excreta collection. Excreta were collected for 48 h.

In conjunction with the 5 day bioassay, a second experiment was con-ducted using 200 10-day-old male broiler chicks (average weight = 248 g)from the same flock placed into cages, ten chicks per cage. Each cage wasassigned one of the previously described diets. The chicks were offered unlim-ited access to both water and experimental diets for a 2-week period. At 24days of age, feed consumption was recorded, all chicks were weighed, killedby CO2 asphyxiation and the tibiae were collected, cleaned and frozen foranalysis. Phosphorus sources, diets and excreta samples were analysed foracid-insoluble ash using the dry ash and hydrochloric acid digestion techniqueof Scott and Balnave (1991). Diet and excreta phytate phosphorus were mea-sured as IP6 (inositol hexa-phosphate) using ion-exchange chromatography(Bos et al., 1991). Total phosphorus and calcium were measured by an induc-tively coupled plasma (ICP) emission spectroscopic method (AOAC, 1990).

Phosphorus retention from the basal diet was determined as 43.2% (Table10.12). It was determined that the non-phytate phosphorus portion of themaize and soybean basal was only 65.5% retainable, not 100% as is widelyassumed when formulating diets. However, the 32.3% retention of the phytatephosphorus masked the incomplete retention of the non-phytate phosphorus.Although true for the maize and soybean diet, this may not be the case whenother ingredients are used. The data indicated that retentions of total phosphorus


Table 10.11. Hydrolysis of inositol hexaphosphate and retention of total phosphorus by laying hens ofthree feed ingredients with or without 300 FTU phytase as determined with a 3-day excreta collection(Leske and Coon, 1999).

Food intake Hydrolysis Total PDiet n (g day1) SD of IP6 SD retention SD

% %Soybean meal 7 65.9abc 23.3 25.7b,y 4.7 36.8b,x 8.4Soybean meal and phytase 7 61.6bc 21.5 62.4a,c 9.5 53.4a,c 9.5Maize 7 48.0c 18.2 23.0b,y 11.0 28.6b,y 4.4Maize and phytase 8 46.3c 23.1 52.0a,d 6.3 44.7a,d 3.0Rice bran 8 79.1ab 23.6 36.1b,x 8.5 35.9b,x 3.5Rice bran and phytase 8 82.3a 21.7 50.9a,d 5.5 43.0a,d 6.1

a,b,cMeans within column with differing superscripts are significantly different (P 0.05).a,bMeans within a specific feed ingredient treatment and column with differing superscripts are signifi-cantly different (P 0.05).c,dMeans within the added phytase treatment and same column with differing superscripts are signifi-cantly different (P 0.05).x,yMeans within the no added phytase treatment and same column with differing superscripts are signifi-cantly different (P 0.05).


and phosphorus from calcium phosphates supplements were dependent onthe dietary concentration of phosphorus (Table 10.13). When feedingextremely low levels of a test calcium phosphate source (

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Poultry Feedstuffs Supply Composition and Nutritive Value

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