1. VTS 150 Animal
Nutrition
Fall 2013
Beth Alden, DVM
Instructor

2. Course Objectives
 Identify the components of the digestive
systems of common companion animals
 Identify the nutritional needs of common
companion animals
 Correctly calculate the caloric needs of
companion animals
 Correctly evaluate a pet food label and
ingredients
 Identify common toxins for companion
animals

3. Resources for Class
 Textbook:
 Nutrition for Veterinary
Technicians and Nurses,
Ann Wortinger,
 Blackwell Publishing, 2007

4. Resource for Class
 Case Studies in Veterinary
Technology
 Authors Jody Rockett and
Chani Christensen
 Students will be required
to complete assigned case
studies and turn them in

5. Resources on Library Reserve
Small Animal Clinical
Nutrition 4th
Edition, Hand,Thatcher, R
emillard, Roudebush,
The Mark Morris
Institute, 2000

6. Students requirements
 Exams
 Discussions
 Toxin project
 Case studies
 Final project

7. Classification of Digestive
Systems

8. Digestive System
 Connects animals diet with metabolic needs
 A muscular tube from mouth to anus
grinding, mixing, moving and absorbing nutrients
 Glands manufacture secretions that are added to
the tube to assist in digestion
 Ruminants harbor bacteria in the digestive tract
that assist in digestion and synthesis of essential
nutrients
 All animals have microbes in the digestive tract
that assist in digestion, veterinarians are harnessing
their power as nutracueticals ( beneficial bacteria
administered to animals)

9. Diet and digestive tract
 Herbivores – plant eaters
 Carnivores- meat eaters
 Ominivores- plant and meat eaters
 Insectivores – insect eaters
 Frugivore – fruit eaters ( many species eat
fruit as part of their diets, these animals
eat only fruit like some bats)

10. Digestive tracts
 The anatomy of the digestive tract is
designed for the type of food the animal
utilizes
 Carnivores have short digestive tracts that
hold a small volume of food
 Herbivores have large digestive tracts that
hold a large volume
 Insectivores and frugivores have digestive
tracts that are designed for that diet

11. Herbivores
vegetation, nitrogen source, minerals and water
Difficult to digest, large complex gut is needed
- Plant cell walls are hard to break down
- Cellulose is the storage form of the plants glucose
- Microbes in the gut break down the cellulose and
utilize the glucose to make their energy and
volatile fatty acids ( butyric, proprionic and acetic
acid)
- The animal utilizes these volatile fatty acids
- Very little of the food’s energy is actually absorbed

12. Carnivores
 Animal material ( flesh, muscle etc) makes
up the diet
 More easily digested than herbivore diet
 GI tract is basically a simple tube
 Most of the food energy is utilized and
absorbed
 Mechanical breakdown of food is less
involved

13. Digestive system types
 Monogastric
- One “true” stomach ( dogs, cats, pigs,
horses)
 Ruminant
- Four compartment stomach
- Rumen, reticulum, omasum, abomasum
- Cows, sheep, goats

14. Types of Digestive Systems

15. Monogastric Stomach
 Five sections
- Cardia
- Fundus
- Body
- Antrum
- Pylorus

16. The 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

17. The Monogastric Stomach
2. Fundus
 Located below the
cardia
 Blind pouch that
distends as food is
swallowed
Source: University of California at Davis
FUNDUS
CARDIA

19. The 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

20. The 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

21. Ruminant Animals

22. Ruminant
 Chews food briefly and swallows
 Regurgitates “cud” to chew again and
swallow ( vital to help break down
cellulose)
 The stomach is designed to allow this
regurgitation and swallowing, plus the
action of microbes on the diet ( four
compartment stomach)

23. The Ruminant Stomach
 Four Compartments:
Reticulum
Rumen
Omasum
Abomasum
Source: University of California at Davis
head tail

24. Source: University of California at Davis
head
The 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

25. The 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

26. The 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

27. The Ruminant Stomach
© University of Bristol, 1988
Pillar PapillaePapillae

28. Cow Digestive System

29. The Ruminant Stomach
The Rumen
During contractions, pillars close off
certain sacs of the rumen which
allows mixing of rumenal contents
Mixing of contents essential for
fermentative function of rumen
RUMEN

30. Rumen continued
 During contractions, pillars close off certain
sacs of the rumen which allows mixing of
rumenal contents
 Mixing of contents is essential for fermentation
in the rumen
 Fermentation breaks down the nutrients for
the microbes and the animal and produces
vitamins B and K
 Carbon dioxide and methane are the
byproducts of this process

31. Reticuloruminal contractions
 Allow “cud” to be regurgitated into the
esophagus and into the mouth where it is re-
chewed and re-swallowed ( helps break
down this difficult to digest diet)
 Allows “eructation” of built up carbon dioxide
and methane gas in the rumen. Gasses are
forced into the reticulum and up the
esophagus
 Interference with eructation leads to bloat
which can be deadly

32. Fermentative digestion
 Begins in the rumen
 Bacterial, protozoal and a small amount
of fungi utilize their enzymes to begin
breaking down food
 The microbes utilize the energy in the diet
to grow and reproduce

33. Carbohydrate metabolism
 Cellulase enzymes digest cellulose and
transform the complex carbohydrate into
simple sugars
 These simple sugars are not available to the
host animal ( like they are in monogastric
animals) instead they are absorbed and
utilized by the microbes which produce
Volatile Fatty Acids ( VFA’s)
 The host animal utilizes the volatile fatty acids

34. Carbohydrate Metabolism
Continued
 Volatile fatty acids are the byproducts of
anaerobic fermentation by microbes in
rumen
 Anaerobic fermentation means it does
not utilize oxygen
 Some of the VFA’s are utilized by the
ruminant to produce glucose
 Other VFA’s are used to produce adipose
tissue and milk fat

35. Protein Metabolism
 Rumen microbes digest proteins just like
carbohydrates
 Proteases ( enzymes) reduce long proteins
to amino acids ( the building blocks of
proteins) and short chain peptides ( short
chains of amino acids)
 Peptides are either incorporated into the
protein structure of the microbes OR
converted to ammonia ( NH3+) and VFA’s

36. Protein Metabolism
Continued
 Liver secretes urea into the rumen, this
provides the rumen microbes with additional
nitrogen ( the rest of the nitrogen they get
from digesting the proteins in the diet)
 Microbes get flushed from the reticolorumen
to the omasum, abomasum and intestines
where they serve as an additional protein
source for the host animal
 Urea is sometimes added to poor quality
feeds to meet the nitrogen needs of the
animal

37. Other rumen notes
 Microbes provide B vitamins, and vitamin
K
 The rumen environment is a delicate
balance of food, microbial growth and
by-products
 Abrupt changes in diet severely affect the
production of methane, CO2, VFA’s and
ammonia causing fermentation and
changes in rumen ph

38. The Ruminant Stomach
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

39. Omasum primary functions
 Break down food particle further and move
them into the abomasum
 Absorb any excess VFA’s
 Remove bicarbonate ions from ingesta ( to
avoid altering acid ph of abomasum)
 Bicarbonate ions come from the saliva (
ruminants produce a huge amount of saliva
which goes into the rumen to help buffer ph)
 If saliva flow is blocked by a foreign object or
lack of production, the animal can become
severely acidotic ( remember VFA are ACIDS)

40. The Ruminant Stomach
Abomasum
 “True stomach” of
ruminant
 Functions similar to
monogastric
stomach
ABOMASUM
Source: University of California at Davis
head tail

41. Young Ruminant Digestive
Tract
 Functions as a monogastric stomach
 No fermentative digestion ( rumen and
reticulum are non functional)
 Reticular groove or esophageal groove
forms when suckling and allows milk to go
directly to omasum
 Bucket fed calves don’t form this groove
and milk spills into the rumen and
reticulum

42. Young ruminant continued
 Abomasum is largest of 4 stomachs for the
first few weeks of life
 Rumen and reticulum development rate
depends on diet
 - grain and hay fed- develops at 3 weeks
 - milk fed develops at 3 months
 Veal calves are fed milk for their entire
short lives to produce a very tender soft
meat,

43. Digestive System Chronology
 GI tract extends from mouth to the anus
and performs different functions at
different sections
1. Prehension
2. Mechanical grinding down of food
3. Chemical digestion of food
4. Absorption of nutrients and water
5. Elimination of waste material

44. Prehension
 Grasping with teeth or lips
 Cows do not have upper incisors, they
have a toothless area called a dental
pad
 Cows use the bottom incisors and dental
pad to bite grass
 Dogs, cats have sharp tearing teeth to rip
flesh

45. Mechanical grinding down of
food
 Carnivores have pointed teeth to facilitate
holding and tearing of food
 Herbivores have flat surface molars that grind
from side to side to break down plant material
( watch a rabbit chew, horses, cattle chew the
same way)
 horses form sharp edges ( points) on their
molars that have to be filed down from time
to time ( floating the teeth)

46. Chronology of Digestion:
Mechanical Grinding Down of Food
Carnivore Teeth
Pointed to facilitate holding and tearing of food
© Clinical Textbook for Veterinary Technicians 6th ed.; McCurnin, Bassert

47. Chronology of Digestion:
Mechanical Grinding Down of Food
Incisors – Teeth in the front
for holding and tearing
Canines – Pointed teeth
located at corners for
tearing and shredding
Premolars – Located just
before the molars and
are used for grinding in
all species
Molars – Used for grinding

48. Chronology of Digestion:
Mechanical Grinding Down of Food
Herbivore Teeth
Flat, occlusal surface for grinding

49. Ruminant Teeth
No upper incisors or upper canine teeth
Chronology of Digestion:
Mechanical Grinding Down of Food
Dental Pad
Thick
connective
tissue
Diastema

50. Teeth terminology
 Maxilla – upper jaw
 Mandible- lower jaw
 Lingual- inner side of lower arcade of teeth
that face the tongue
 Labial- outer surface of upper and lower
arcade teeth that face the lips
 Palatal- inner side of upper arcade teeth that
face the palate
 Buccal- outer side of teeth on sides of mouth
that face the cheeks

51. Canine Triadan Numbering

52. Canine Dental Formula
 Triadan

53. Feline Triadan Numbering

54. Feline Dental Formula
Triadan

55. Chemical digestion of food
 Saliva mixes with food during chewing
 Three pairs of salivary glands located
bilaterally ( one on each side)
 Parotid (2), mandibular(2), lingual (2) salivary
glands
 Saliva
1. moistens, softens, shapes and lubricates
food
2. Aids in taste, acts as a buffer
3. Provides digestive enzymes

56. Chemical Digestion of food
continued
 Digestive enzymes and buffers in saliva
1. amylase- in omnivore saliva, not present
in carnivores, breaks down amylase a
sugar component of starch
2. Lipase- breaks down lipids
3. Bicarbonate and phosphate buffers- in
cow saliva, neutralizes acids in rumen
and maintain normal rumen ph ( up to
25-30 gallons of saliva a day)

57. Chemical Digestion of food
continued
 Food moves from mouth to pharynx
where the epiglottis prevents food from
entering the trachea
 Food is transported into the esophagus
 Esophagus utilizes peristalsis, rhythmic
contractions to propel food to the
stomach

58. Chemical digestion of food
 Stomach
1. Stores food
2. Continues enzymatic breakdown of food (
pepsin, gastrin, mucus, hydrochloric acid all
play a role)
3. Mechanical breakdown of
food, mixing, grinding, contractions that
move food
4. Ruminants have specific compartments with
different functions (
rumen, reticulum, omasum, abomasum)

59. Chemical Digestion continued
 Liver- secretes bile acids to help with
digestion of fats, keeps the fats in solution
 Pancreas- secretes enzymes into small
intestine for breaking down nutrient
1. Protease for proteins
2. Amylase for carbohydrates
3. Lipase for fats/lipids
4. Bicarbonate to neutralize stomach acid

60. Absorption of nutrients and
water
 Small intestine consists of three parts,
duodenum, jejunum and ileum
 Continues peristalsis
 Villi and microvilli increase surface area
for absorption
 No clear demarcation between three
segments
 All 3 segments perform peristalsis, absorb
nutrients and water

61. Small Intestine
 Duodenum- first portion of the small
intestine receives contents of stomach
 Jejunum- majority of small intestine
 Ileum- where small intestine enters the
colon ( the cecum is located at this
junction)
 Cecum is very small in carnivores and
large in herbivores like horses

62. Villi
 Villi-
- millions of cylindrical fingerlike projections
from the intestinal wall
- Provide large surface area for absorbing
nutrients
- Crypts surround villi and replenish the cells
that cover the villi

63. Microvilli
 Microvilli
- Brush border, extensions of the surface of the
cells that cover the villi
- Increase the surface area of the cells and the
absorptive capacity
- Contain digestive enzymes
- Clinical example
TGE transmissable gastroenteritis in pigs and
parvovirus in dogs attack and destroy the villi
preventing absorption of nutrients from the
intestinal tract

64. Functions of Small Intestine
 Small intestine absorbs electrolytes (
Na, Cl, K, etc) water, and vitamins
 Absorbs carbohydrates, fats, proteins after
chemical digestion via enzymes

65. Nutrient digestion in the small
intestine
 Carbohydrates- digested by amylase
secreted from the pancreas
 Proteins- digested by proteases secreted
by the pancreas
 Fats- digested by bile acids from liver (
helps emulsify fat ( keep in
solution), further broken down by lipase
secreted from pancreas

66. Elimination of Waste Material
 Large intestine: cecum and colon
- Recover fluid and electrolytes
- Store feces until elimination
- Some microbial action
- Differences between species dependent
on diet

67. Elimination of Waste material
 Carnivores
- colon- simple, tubular, contracts to move
feces through
- Cecum “ blind sac” poorly developed
 Herbivores
- Colon – large bacterial population of
microbes for fermentation
- Cecum “blind sac” more developed,
larger than carnivore

68. Colon
 Colon in carnivore is much smaller than in
herbivores
 Responsible for reabsorbing water and
electrolytes

69. Elimination of Waste in
herbivores such as horses
 Colon and 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 most common form of colic in horses

70. Equine Digestive System

71. Rectum and Anus
 Rectum
- Terminal portion of colon
- Contains mucus secreting glands
- Sensory receptors detect
stretching/distension and triggers
defecation
 Anus
- Internal and external sphincters allow
controlled passage of feces

72. Next Week… Session 2:
Basic Nutrients