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

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

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

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.

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

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.

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.

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

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

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

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

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

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

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.

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

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

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

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

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.

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

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).

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

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

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.

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.

Poultry Digestive System