1. Anatomy, Physiology & Absorption of Nutrients Animal Science II
Digestive Systems
Anatomy, Physiology & Absorption of Nutrients
Animal Science II

2. Objectives
Name, locate and describe the functions of the parts of the digestive systems of ruminant and nonruminant animals
Classify farm animals as ruminant and nonruminant
Explain the relationship of types of digestive systems to the ability of ruminants and nonruminants to digest and absorb different classes of feed

3. Defining the Digestive Systems
Digestion-the process of breaking feed down into simple substances that can be absorbed by the body
Absorption-taking the digested parts of feed into the bloodstream
Digestive System (tract)-consists of parts of the body involved in chewing and digesting feed
This system also moves the digested feed through the animals body and absorbs the products of digestion

4. Parts of the Digestive System
Mouth
Esophagus- tube like passage from mouth to stomach
Stomach-receives feed and adds chemicals that help digestive process
Small Intestine-long folded tube attached to the lower end of the stomach. Feed absorption occurs here
Large intestine-larger in diameter, shorter
Rectum-end of the large intestine
Anus-where undigested material called feces is passed from the body
Also includes accessory organs
Teeth, tongue, salivary glands, liver, pancreas

5. Poultry Digestive System
No teeth
Crop and gizzard
Ceca
Cloaca
vent

6. Digestive Capacities Vary greatly among different species of animals
Species, age, breed and size of animals also affect capacity
Table 5-3
Ruminants are generally larger than nonruminants

7. Ruminants
Animals that have a stomach that is divided into several parts
Cattle, sheep, goats, llamas, bison, deer
Can digest large quantities of fibrous feed called roughage
Roughages are hay, grass, silage
This is due to the bacteria present in their digestive system. Bacteria produce proteins, B-complex vitamins and vitamin K

8. Nonruminants Animals that have simple, one compartment stomachs
Swine, horses, poultry
Require high energy, low fiber rations called concentrates
Concentrates are grains and protein supplements
Ruminant vs. Nonruminant usage of roughage
Cattle and sheep 44% compared to swine 22%
Horses fall in the middle at about 39%

9. Assignment
Read p. 117 Mouth and Esophagus

10. The Ruminant Stomach

11. Parts
Rumen
Reticulum
Omasum
Abomasums

12. Rumen Contain millions of protozoa and bacteria
Muscles help break the food down into smaller particles so it is easier for bacteria to act
No division between it and the Reticulum

13. Reticulum Hardware stomach
Foreign objects such as wire and nails go here and are held
Thick walls

14. Omasum
8% of stomach
Strong muscles that grind up feed and squeeze out some water but how much is not know
Somewhat of a mystery area

15. Abomasum “true” stomach 7% stomach Feed is mixed with gastric juices
Digestion is carried out here just like nonruminants

16. How it Works Eat rapidly
Do not chew much of their feed before swallowing
Solid part of the feed goes to the rumen; liquid part goes into the reticulum then the omasum and on into the abomasum
In the rumen feed is partially broken down and mixed by bacteria. A slow churning and mixing takes place
When full the animal lies down and feed is forced back into the mouth and rumination occurs.
Cattle chew their cud 6-8 times per day

17. Development of the Ruminant Stomach
Abomasums is the only part that functions
Young ruminants can not use roughages
Milk goes directly the abomasums
When born the rumen is small and found in the upper left part of the abdomen
After 2 months of age the rumen moves to its normal position
The reticulum and omasum grow and develop rapidly
By 3 months of age the rumen has grown enough to begin to function

18. Assignment
Read p The Nonruminant stomach –Large Intestine

19. Digestion in Poultry
Possess certain special digestive organs not found in other animals
Feed first goes to the crop
Stored and softened by saliva and secretions from the crop wall
Muscular stomach
Lined with a thick, horny membrane like material called epithelium
Feed particles are crushed and mixed with digestive juices by the gizzard
Ceca
Two blind pouches where the small and large intestine join
About 7” long
Function is unknown but usually filled with soft, undigested food
Cloaca
Enlarged part where the large intestine joins the vent
Vent
Area of passage from the body for
Feces from the large intestine
Eggs from the oviduct
Urine from the kidneys

20. Absorption of Feed Most takes place in the small intestine
Villi-small finger shaped projections on the wall of the intestine are key to absorption because they increase the surface area of the intestine
As substances are absorbed by the blood capillaries in the villi, they pas through the liver and then the blood
Water and dissolved minerals are also absorbed in the small intestine

21. Digested Protein Absorbed in the form of amino acids
Some sodium must be present for absorption to properly occur

22. Digested Carbohydrates (Starches & Sugars)
Present as monosaccharide's
Glucose
Fructose
Galactose

23. Fiber In the form of short-chained fatty acids
Adenosine triphosphate (ATP) supplies the energy for the absorption of the monosaccharide's and fatty acids
Sodium must also be present

24. Digested Fats (soaps and glycerol) X
Form into fats again and are absorbed by the lymph vessel in the villi.
They pass through the thoracic duct in the neck and into the circulatory system

25. Absorption in the Large Intestine
Water and some nutrients are directly absorbed into the bloodstream through capillaries in the intestinal wall
This is especially important in horses because much of the microbial digestion of roughage occurs in the cecum

26. End of the Nutrients Journey
Most in the muscle cells
Some are deposited in the liver
Used to replace worn out cells and build new for energy or stored as fat for later use

27. Metabolism
Sum of the processes, both chemical and physical that are used by living organisms and cells to handle nutrients after they have been absorbed from the digestive system

28. Process Anabolism—formation and repair of body tissue
Catabolism—breakdown of body tissues into simpler substances and waste
Oxidation of nutrients provides energy

29. Summary Ruminants can use a lot of roughage
They have a 4 part stomach in which bacteria breakdown the roughages
Nonruminants must have more concentrates such as grain, in their ration because they have simple one part stomachs
Most digested feed is absorbed in the small intestine of the animal
Small intestine has millions of tiny villi