1. The process of breaking down feeds so the body can use them
Digestion
The process of breaking down feeds so the body can use them

2. Four steps in digestion
1. Obtaining food and taking into the body
2. Breaking food down
3. Absorbing nutrients
4. Elimination of undigested wastes

3. Obtaining Food Animals use their SENSES to find FOOD.
Food is taken in through the MOUTH. This is called INGESTION.

4. Amount of Food Ingested is determined by:
Hunger -- the intrinsic desire for food, regardless of food type or preference
Appetite -- the specific type of food that is preferentially sought.

5. What Animals Eat
Herbivore -- majority of diet comes from plant products
Examples -- Cow, Sheep, Goat, Horse, Rabbit
Carnivore -- majority of diet comes from animal products
Examples -- Dog
Omnivore -- eats both plant and animal products
Examples -- Humans, Pigs, Poultry, Mouse

6. Breaking Food Down Food is broken down in two ways:
1. CHEMICAL -- the use of chemical substances (ENZYMES) to dissolve the food.
2. MECHANICAL -- the use of PHYSICAL structures (chewing, grinding) to break the food apart.

7. Food is broken down in the following structures:
Mouth -- MASTICATION -- grinding or chewing of food
SALIVA--watery liquid in mouth that begins dissolving the food.

8. Mastication -- Teeth Incisors -- cutting and food intake action
55 psi
Canines -- ripping and biting (Carnivores and Omnivores only)
Premolars -- grinding action
Molars -- grinding action
200 psi

10. Esophagus the muscular tube connecting the MOUTH with the STOMACH
PERISTALSIS -- the movement of food through the digestive system by a series of muscular contractions
Analward Peristaltic Movements

11. Stomach Compartment used for digestion and storage
Cattle and sheep (RUMINANTS) have 4 compartments
Horses and swine (NONRUMINANTS) have 1 compartment

12. Absorbing Nutrients
Nutrients leave the digestive tract and enter the blood so they can be used by every cell

13. Small Intestine
most of the food nutrients are absorbed into the blood here
The small intestine is very LONG and contains many small folds called VILLI which increase the surface area for more absorption.
Three parts
Duodenum, Jejunum, Illeum

14. Large Intestine
Water is absorbed into the blood and undigested wastes prepare to leave the body

15. Removal of Undigested Wastes
Not all of the food eaten can be digested and absorbed.
After most of the water is absorbed, waste is removed from the body through the anus or vent.

16. Other organs that assist in digestion
liver -- stores carbohydrates (glycogen), detoxifies blood, produces bile
pancreas -- produces insulin and pancreatic juice
gall bladder -- stores bile until it is needed

17. Terminology of feed as it moves through the system
Feed or Feedstuff
Ingesta
Cud
Chyme
Digestive End Products (DEP’s)
Fecal Material or Non-Digested End Products
Feces

18. The GI tract -- Descending
Oral cavity (mouth)
Incisors
Molars
Esophagus
Stomach
1 compartment, or
4 compartments
Small Intestine
Duodenum
Jejunum
Illeum
Cecum
Large Intestine (Colon)
Rectum
Anus

19. Chemical Digestion
The body produces chemicals (Enzymes) that help dissolve feed.
Refer to chart.

20. Ruminant Digestive Systems (Polygastric)
Cattle and sheep have a Ruminant digestive systems. This means that their stomachs have four compartments. The first of these compartments contains bacteria that help break down roughage.
Cellulose- a substance found in the cell walls of plants. It cannot be used unless it is first soaked (fermented) by microorganisms.

22. Two Types of Microorganisms:
Bacteria and Protozoa are one-celled animals. Muscles in the rumen and reticulum help break the food into smaller particles.

23. Regurgitation
Ruminants consume large amounts of roughages. It is first chewed just enough to swallow it. After they consume the food, they regurgitate it, or force it back into the mouth, so that it can be chewed again. (Chewing Cud).

24. 4 Parts of the Ruminant Stomach
Ruman- the largest compartment; stores and ferments the feed.
Reticulum- foreign particles (nails, wire) are removed (cow magnets)
Omasum- eliminates water from the feed
Abomasum- (true stomach)- gastric juice is secreted; feed is broken down

25. Monogastic Digestive System
Swine, dogs, bears, and humans have only one stomach. It is difficult for these animals to digest roughages.

27. Modified Monogastric System
Horses and rabbits have only one stomach, but have structures that contain microorganisms so they can digest roughages. Microorganisms are found in the Cecum.

29. Avian Digestive System
Birds (Turkeys, Chickens and Pigeons) have crops not found in other species that allow them to digest whole seeds and other hard foods.
Crop- food storage
Gizzard- feed particles are crushed and mixed with digestive juices
Cloaca- an enlarged part found where the large intestine joins the vent.

30. Poultry Digestive System