1. Animal Digestion

2. What do I eat? 1. 2. 3. A. B. C.
Knowledge of the different types of digestive systems is critical in selecting the proper feeds for livestock.
Understanding the chemical and physical changes that occur during the digestive process leads to more efficient livestock feeding.

3. Objectives Sort animals by their digestive systems
Describe and compare different types of digestive systems
Demonstrate the functions of the digestive system

4. What is Digestion?
Digestion: Is the process of breaking down food into simple substances that can be absorbed by the body.
Absorption: is the process of taking the digested parts of food into the bloodstream.

5. What is the Digestive System?
The digestive system consists of the parts of the body involved in chewing and digesting food.

6. Types of Digestive Systems
This system also moves the digested food through the animal’s body and absorbs the products of digestion.
Different species of animals are able to digest certain types of feeds better than others.
This difference occurs because of the various types of digestive systems found in animals.

7. Types of Digestive Systems
Ruminant
Monogastric
Pseudo-Ruminant
Avian

8. Types of Digestive Systems
Ruminant
Contains one large stomach with four compartments
Animals are typically herbivores and can make good use of forages
Regurgitate feed, chew on their cud
Examples: Cattle, Goats, Sheep

9. Types of Digestive Systems

10. Types of Digestive Systems
Monogastric
Simple stomach structure with one compartment
Can be omnivores or herbivores, are less efficient at utilizing forages
Examples: Swine, Dogs, Cats, Humans

11. Types of Digestive Systems

12. Types of Digestive Systems
Pseudo-Ruminant
Found in animals that eat large amounts of roughages but do not have stomachs with several compartments.
Performs some of the same functions as found in ruminants.
Can utilize large amounts of roughages because of its greatly enlarged cecum and large intestine.
Often eats forages as well as grains and other concentrated feeds.
Examples are horses, rabbits, guinea pigs, and hamsters.

13. Types of Digestive Systems

14. Types of Digestive Systems
Avian
Digestive system found in poultry
This system differs greatly from any other type.
Since a bird has no teeth, no chewing is involved.
The esophagus empties directly into the crop.
The crop is where the food is stored and soaked.
From the crop, the food makes its way to the gizzard.
The gizzard is a very muscular organ, which normally contains stones or grit that grinds the food.
Digestion in the avian system is very rapid.

15. Types of Digestive Systems

16. Types of Digestive Systems
Ruminant
Monogastric
Psuedo Ruminant
Avian
Cattle
Sheep
Goats
Swine
Dogs
Cats
Horses
Rabbits
Guinea Pigs
Hamsters
Chicken
Turkey

17. Digestive System Functions

18. Digestive System Functions
Mouth: The chewing action of the mouth and teeth breaks, cuts, and tears up the food.
Teeth: Break down food for swallowing, increase surface area of food particles
Tongue: helps with swallowing

19. Digestive System Functions
Pharynx: connects the mouth to the esophogus
Esophagus: chewed food passes from the mouth to the stomach through a muscular tube called the esophagus

20. Digestive System Functions
Saliva
stimulates the taste of the food but also contains enzymes (enzymes are organic catalysts that speed up the digestive process)
Salivary amylase changes starch to maltose, or malt sugar.
Salivary maltase changes maltose to glucose.
Chewed food passes from the mouth to the stomach through a muscular tube called the esophagus.

21. Digestive System Functions
Monogastric Stomach
Muscular organ that stores food and releases it into the small intestine
Breaks down food into a liquid mixture and mixes it with enzymes
The low pH destroys most bacteria and begins to break down the food materials.
Animals with this type of digestive system are better adapted to the use of concentrated feeds, such as grains, than to the use of large quantities of roughages.

22. Digestive System Functions
Ruminant Stomach
Rumen
Lined with papillae to increase surface area
Contains microorganisms that digest cellulose and synthesize amino acids
It accounts for approximately percent of the stomach.
Contains bacteria and other microbes that promote fermentation.
Is designed so that food can be ingested, eructated (belched up), chewed, and then swallowed again.

23. Digestive System Functions
Ruminant Stomach
Reticulum
It is sometimes considered an extension of the rumen.
The reticulum has honeycomb-like ridges.
It aids in keeping the food in the rumen mixed with water and saliva until it is the right consistency.
Once the right consistency is reached, the mixture can pass on into the lower digestive tract.

24. Digestive System Functions
Ruminant Stomach, cont.
Omasum
is a small compartment that is the main sight for water absorption.
The particles are squeezed and dehydrated, as well as sorted.
The compartment acts as a filter for the abomasum.
Has many folds

25. Digestive System Functions
Ruminant Stomach, cont.
Abomasum
True stomach where digestion takes place
It secretes gastric juices consisting of hydrochloric acid and pepsin.
These juices kill and then digest the microbes that have passed with the food materials from the rumen.
The abomasum is similar to the stomach in a monogastric animal.

26. Digestive System Functions
Small Intestine

27. Digestive System Functions
Small Intestine
long coiled tube connecting stomach to large intestine
The partly digested food that leaves the stomach enters the small intestine as an acidic, semifluid, gray, pulpy mass. This is called the Chyme
Duodenum: most digestion occurs here
Jejunum: some digestion and some absorption occur
Ileum: mostly absorption

28. Digestive System Functions
Small Intestine, cont.
The chyme is mixed with three digestive juices: pancreatic juice, bile, and intestinal juice.
Pancreatic juice, secreted by the pancreas, contains the enzymes trypsin, pancreatic amylase, pancreatic lipase, and maltase.
Pancreatic amylase changes starch in the food into maltose.
Bile is a yellowish-green, alkaline, bitter liquid produced in the liver.
aids in the digestion of fats and fatty acids.
Glands in the walls of the small intestine produce intestinal juice.
Contains enzymes that are used in digestion.

29. Digestive System Functions
Large Intestine
Includes the cecum, colon, rectum
Main function is to absorb water
Forms indigestible wastes into solids
Some vitamins and minerals absorbed here

30. Digestive System Functions
Large Intestine, cont.
The key to absorption in the large intestine is the small fingerlike projections on the walls, called villi.

31. Digestive System Functions
Large Intestine, cont.
Food materials not digested or absorbed are called feces.
These materials are moved through the large intestine by muscles in the intestinal walls.
The undigested part of food is passed out of the body through the anus, the opening at the end of the large intestine.

32. Digestive System Functions
Large Intestine, Cont.
Cecum
Present in monogastrics
“blind gut,” is found where the small intestine joins the large intestine.
It has little function in most animals.
In a pseudo-ruminant, the roughages consumed are digested by the bacterial action in the cecum.