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VTS 150VTS 150Animal NutritionAnimal Nutrition
Fall 2010Fall 2010
Instructor: Beth Alden, DVM
Course ObjectivesCourse Objectives
Understanding of different digestive systems
Learn the nutritional needs of small companion animals, “pocket pets,” large animals and exotic pets
Learn about nutritional diseases for several species
Learn how to calculate an animal’s energy needs
Know how to evaluate a pet food label and ingredients
Learn common toxicities for dogs and cats
Resources for ClassResources for Class
TextbookTextbook:
Nutrition for Veterinary Technicians and Nurses, Ann Wortinger,Blackwell Publishing, 2007
Resources on Library ReserveResources on Library Reserve
Small Animal Clinical Nutrition 4 th Edition, Hand,Thatcher, Remillard, Roudebush, The Mark Morris Institute, 2000
What’s Required of You:What’s Required of You:
2 Unit ExamsThree (3) Student ProjectsFinal Exam
Digestive System Classifications
Digestive ClassificationsDigestive Classifications
Two Methods of Digestive System Classification
Food Source Stomach Type
Herbivores: Plant eaters
Carnivores: Meat Eaters Omnivores: Plant and Meat Eaters
HerbivoresHerbivores
Plant material makes up diet• Rough vegetation, nitrogen source, minerals & water
Difficult to digest• Plant cell wall is hard to break down • Energy from the plant is tied up in cellulose that animal cannot
digest on its own• The animal has developed a large complex gut to digest this
material• Microbial action in gut is necessary to break down the cellulose
and release its energy• Little of the food’s energy is absorbed by host
CarnivoresCarnivores
Animal material (flesh, muscle, etc.) makes up diet
Food more easily digested than in herbivores
The animal has a very simple “gut “
Most of food’s energy is absorbed by host
Mechanical breakdown of food is less involved
Types of Digestive SystemsTypes of Digestive Systems
Four compartment stomach:Reticulum, Rumen,
Omasum & Abomasum
(cows, sheep, goats)
One “true” stomach
(dogs, cats, pigs, horses)
RuminantMonogastric
Monogastric AnimalsMonogastric Animals
The Monogastric StomachThe Monogastric Stomach
Five sections:
◦ Cardia◦ Fundus◦ Body◦ Antrum◦ Pylorus
Source: University of California at Davis
The Monogastric StomachThe Monogastric Stomach
1. Cardia Area immediately
surrounding the opening from the esophagus into the stomach
Muscular tone prevents reflux of stomach contents into the esophagus
Source: University of California at Davis
CARDIA
The Monogastric StomachThe Monogastric Stomach
2. Fundus◦ Located below the
cardia
◦ Blind pouch that distends as food is swallowed
Source: University of California at Davis
FUNDUS
CARDIA
The Monogastric StomachThe Monogastric Stomach
3. Body Distends to receive food Rich with gastric glands
Parietal Cells:Hydrochloric acid (HCl)
Chief Cells: Pepsinogen
Mucous Cells: Mucus
BODY
Source: University of California at Davis
FUNDUS
CARDIA
BODY
The Monogastric StomachThe Monogastric Stomach
4. Antrum Grinds up food and
regulates HCl
Also contains glands
BODY
Source: University of California at Davis
FUNDUS
CARDIA
BODY
ANTRUM
G Cells: Gastrin
Mucous Cells: Mucus
The Monogastric StomachThe Monogastric Stomach
5. Pylorus Muscular ring
(sphincter)
Regulates movement of chyme from stomach into duodenum
Helps prevent backflow of duodenal contents
BODY
Source: University of California at Davis
FUNDUS
CARDIA
BODY
ANTRUM
PYLORUS
DUODENUM
Ruminant AnimalsRuminant Animals
The Ruminant AnimalThe Ruminant Animal
Chews and swallows its food then regurgitates “cud” to chew on it more before swallowing again
Has a “prestomach” configuration that is adapted to the herbivore diet
Four compartment stomach
The Ruminant StomachThe Ruminant Stomach
Four Compartments:
◦ Reticulum
◦ Rumen
◦Omasum
◦ Abomasum
Source: University of California at Davis
head tail
Source: University of California at Davis
head
The Ruminant StomachThe Ruminant Stomach
1. The Reticulum
Smallest, most cranial compartment
Separated from rumen by the ruminoreticular fold
Muscular wall is continuous with the rumen; contract in coordination
tail
RETICULUM
The Ruminant StomachThe Ruminant Stomach
1. The Reticulum
Honeycombed inside to increase absorptive surface
“Hardware disease”- wires or nails swallowed by animal puncture wall of reticulum
Inside of Reticulum
Source: Colorado State University
RETICULUM
The Ruminant StomachThe Ruminant Stomach
2. The Rumen
Large fermentative vat(40 - 50 gallon capacity)
Processes plant material into usable energy
Lined with “Papillae”
Made up of series of muscular “Pillars”
Source: University of California at Davis
head tail
RUMEN
The Ruminant StomachThe Ruminant Stomach
© University of Bristol, 1988
Pillar PapillaePapillae
The Ruminant StomachThe Ruminant Stomach
2. The Rumen
During contractions, pillars close off certain sacs of the rumen which allows mixing of ruminal contents
Mixing of contents essential for fermentative function of rumen
RUMEN
The Ruminant StomachThe Ruminant Stomach
What reticuloruminal contractions do: Allow “cud” to be regurgitated up the
esophagus, where it’s re-chewed and re-swallowed
Allow “eructation” - built-up CO2 or
methane gas to be expelled from rumen. Gasses are forced into the reticulum and up the esophagus
RUMEN
The Ruminant StomachThe Ruminant Stomach
Fermentative digestion begins in the rumen
Bacterial and protozoal enzymes break down foodstuffs
Carbohydrate Metabolism:◦ Cellulase enzymes digest cellulose (plant cell layer) and
transform complex carbohydrates into simple sugars
◦ Simple sugars aren’t made available to host (like they are in monogastric animals), instead are absorbed into the microbes and converted to Volatile Fatty Acids (VFAs)
RUMEN
The Ruminant StomachThe Ruminant Stomach
Carbohydrate Metabolism, continued
- Volatile fatty acids are by-products of anaerobic fermentation by bacteria in rumen
Some VFAs absorbed into liver then converted to glucose, which is used by the animal’s cells
Other VFAs are used to produce adipose tissue and milk fat
RUMEN
The Ruminant StomachThe Ruminant Stomach
Protein Metabolism: Rumen microbial enzymes attack proteins
(just like carbohydrates)
Proteases reduce long proteins to amino acids and short peptides (short chains of amino acids)
Peptides are either incorporated into the protein structure of the microbes OR converted to ammonia (NH3
+) and VFAs
RUMEN
The Ruminant StomachThe Ruminant Stomach
Protein Metabolism, continued
Liver secretes urea* into the rumen, which provides additional nitrogen for the microbes
Microbes are then flushed from the reticulorumen to the omasum, abomasum and intestines; digested and serve as source of protein to the animal* Urea is sometimes added
to poor-quality feed as a way of increasing nitrogen
value
RUMEN
The Ruminant StomachThe Ruminant Stomach
Other Notes about the Rumen
Provides B vitamins; Vitamin K
Delicate balance: amount of food, growth of microbes and by-products
Changes in diet severely affect production of gas, VFAs and ammonia, causing fermentation process to completely stop
RUMEN
The Ruminant StomachThe Ruminant Stomach
3. Omasum
Muscular organ located off the reticulum
Ingesta moves into omasum from reticulorumen
Prevents large particles from leaving rumen and entering abomasum
OMASUM
Source: University of California at Davis
head tail
The Ruminant StomachThe Ruminant Stomach
3. OmasumPrimary functions◦ Break down food particles
further and move ingesta to abomasum
◦ Absorb any excess VFAs
◦ Remove bicarbonate ions from ingesta (to avoid altering acid pH of abomasum)
OMASUM
The Ruminant StomachThe Ruminant Stomach
4. Abomasum
“True stomach” of ruminant
Functions similar to monogastric stomach
ABOMASUM
Source: University of California at Davis
head tail
Young Ruminant Digestive TractYoung Ruminant Digestive Tract
Functions as a monogastric system
No fermentative digestion (rumen & reticulum are non-functional)
Reticular groove or Esophageal groove allows suckled milk to go to omasum
Suckling is important – helps groove to function
Bucket–fed calves spill milk into rumen & reticulum
Young Ruminant Digestive TractYoung Ruminant Digestive Tract
Abomasum is largest of 4 stomachs for the first few weeks
Rumen & reticulum development rate dependent on diet:
◦ Grain & Hay fed – develop at 3 weeks◦ Milk fed – develop at 3 months
Chronology of Digestive SystemChronology of Digestive System
GI tract extends from mouth to the anus and performs different functions at different parts
Chronology of Digestion: Prehension Mechanical grinding down of food Chemical digestion of food Absorption of nutrients and water Elimination of waste material
Chronology of DigestionChronology of Digestion1. Prehension1. Prehension
Grasping food with teeth or
lips
Chronology of DigestionChronology of Digestion::2. Mechanical Grinding Down of Food2. Mechanical Grinding Down of Food
Carnivore TeethPointed to facilitate holding and tearing of food
© Clinical Textbook for Veterinary Technicians 6th ed.; McCurnin, Bassert
Chronology of Digestion:Chronology of Digestion:2. Mechanical Grinding Down of Food2. Mechanical Grinding Down of Food
Herbivore TeethFlat, occlusal surface for grinding
Chronology of Digestion:Chronology of Digestion:2. Mechanical Grinding Down of Food2. Mechanical Grinding Down of Food
Incisors – Teeth in the front for holding and tearing
Canines – Pointed teeth located at corners for tearing and shredding
PremolarsPremolars – Located just before the molars and are used for grinding in all species
MolarsMolars – Used for grinding
Ruminant TeethNo upper incisors or upper canine teeth
Chronology of Digestion:Chronology of Digestion:2. Mechanical Grinding Down of Food2. Mechanical Grinding Down of Food
Dental PadDental Pad
ThickThickconnectiveconnective
tissuetissue
DiastemaDiastema
Chronology of Digestion:Chronology of Digestion:2. Mechanical Grinding Down of Food2. Mechanical Grinding Down of Food
Positional Location of Teeth - Terminology
MaxillaMaxilla Upper Arcade
MandibleMandible Lower Arcade
LingualLingual Inner side of lower arcade teeth that face tongue
LabialLabial Outer surface of upper and lowerarcade teeth (faces lips)
PalatalPalatal Inner side of upper arcade teeth(faces the palate)
BuccalBuccal Outer side of teeth in back of mouth (faces the cheeks)
Chronology of Digestion:Chronology of Digestion:3. Chemical Digestion of Food3. Chemical Digestion of Food Saliva mixes with food during chewing
Three bilateral pairs of salivary glands in the mouth (parotid, mandibular, lingual)
What saliva does:◦ softens, moistens, shapes & lubricates food◦ aids in taste◦ acts as a buffer◦ provides digestive enzymes
Chronology of DigestionChronology of Digestion3. Chemical Digestion of Food3. Chemical Digestion of Food
Digestive enzymes and buffers in saliva
Amylase: in omnivore saliva – not carnivore breaks down amylose (sugar component of starch)
Lipase: breaks down lipids
Bicarbonate and Phosphate buffers:in cow saliva; neutralizes acids inrumen & maintain normal rumen pH ( up to 25-30 gallons of saliva a day)
Chronology of DigestionChronology of Digestion3. Chemical Digestion of Food3. Chemical Digestion of Food
EpiglottisEpiglottis • Cartilage projection that
prevents food from entering trachea
EsophagusEsophagus - transports food to
stomach• Peristalsis: smooth
muscle contractions to propel food
Chronology of DigestionChronology of Digestion3. Chemical Digestion of Food3. Chemical Digestion of Food
StomachStomach Stores food
Continues enzymatic breakdown of food (pepsin, gastrin, hydrochloric acid)
Mechanical breakdown of food (mixing, grinding and contractions that move food)
Ruminants: each compartment has different function
Chronology of DigestionChronology of Digestion3. Chemical Digestion of Food3. Chemical Digestion of Food
LiverLiverSecretes bile acids to help with digestion of fat
PancreasPancreasSecretes enzymes into small intestine for breaking down nutrients:
Protease for proteinsAmylase for carbohydratesLipase for fats/lipids
Also secretes bicarbonate to neutralize stomach acid
Chronology of DigestionChronology of Digestion4. Absorption of Nutrients & Water4. Absorption of Nutrients & Water
Small IntestineSmall Intestine◦ Duodenum, Jejunum, Ileum
◦ Inner & sub mucosal layer; Muscular layer
◦ Villi & Microvilli increase surface area in intestine◦ Peristaltic waves help move
contents through intestines
Chronology of DigestionChronology of Digestion4. Absorption of Nutrients & Water4. Absorption of Nutrients & Water
Small IntestineSmall Intestine◦ No clear demarcation
between 3 segments
◦ All 3 segments perform peristalsis, absorb nutrients & H2O
Duodenum: first portion of sm. intestine
Jejunum: majority of sm. intestine
Ileum: where sm. intestine enters colon
Chronology of DigestionChronology of Digestion4. Absorption of Nutrients & Water4. Absorption of Nutrients & Water
Villi◦ Millions of cylindrical, fingerlike projections in intestinal
wall◦ Provide large surface area for absorbing nutrients◦ “Crypts” surround villi and replenish cells
Microvilli “brush border”◦ Found on Villi; contain digestive enzymes
• Transmissible Gastroenteritis (TGE) in pigs• Parvo Virus in dogs attack the villus
Animal cannot absorb nutrients from intestinal tract
Chronology of DigestionChronology of Digestion4. Absorption of Nutrients & Water4. Absorption of Nutrients & Water
Small Intestine◦ Absorbs electrolytes
(Na, Cl, K, etc.); water and vitamins across intestinal wall
◦ Absorbs carbohydrates, fats, proteins after they’re chemically digested via enzymes
Chronology of DigestionChronology of Digestion4. Absorption of Nutrients & Water4. Absorption of Nutrients & Water
Nutrient digestion in the small intestine
Carbohydrates:Carbohydrates: digested by amylase secreted from
pancreas
Protein:Protein: digested by proteases secreted bypancreas
Fat:Fat: digested by bile acids from liver (helps emulsify fat to prevent glob formation); further broken down by lipase secreted from pancreas
Chronology of DigestionChronology of Digestion5. Elimination of Waste Material5. Elimination of Waste Material
Large Intestine: Cecum & Colon
◦ Recover fluid and electrolytes
◦ Store feces until elimination
◦ Some microbial action
◦ Differences between species, dependent on diet
Chronology of DigestionChronology of Digestion5. Elimination of Waste Material5. Elimination of Waste Material
ColonCecum “blind sac”
CarnivoresSimple, tubular, contracts to move feces through
Poorly developed
Herbivores*
Large bacterial population (microbes) for fermentation
More developed, larger than carnivore
*Horses are different
Chronology of DigestionChronology of Digestion5. Elimination of Waste Material5. Elimination of Waste Material
Colon & Cecum comprise the “Hindgut”
4 sections: cecum, ventral colon, dorsal colon, small colon
More highly developed than small intestine
Has greater capacity for fermentation
Unique digestion path; colonic impaction is mostcommon form of colic in horses
Chronology of DigestionChronology of Digestion5. Elimination of Waste Material5. Elimination of Waste Material
RectumRectum◦ Terminal portion of colon◦ Contains mucus-secreting glands◦ Sensory receptors detect
stretching/distension andtriggers defecation
AnusAnus◦ Internal & External sphincters allow
controlled passage of feces
Next Week…Next Week…
Session 2:
Basic Nutrients