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

Four steps in digestion z1. Obtaining food and taking into the body z2. Breaking food down z3. Absorbing nutrients z4. Elimination of undigested wastes

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

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

What Animals Eat zHerbivore -- majority of diet comes from plant products yExamples -- Cow, Sheep, Goat, Horse, Rabbit zCarnivore -- majority of diet comes from animal products yExamples -- Dog zOmnivore -- eats both plant and animal products yExamples -- Humans, Pigs, Poultry, Mouse

Breaking Food Down zFood is broken down in two ways: z1. CHEMICAL -- the use of chemical substances (ENZYMES) to dissolve the food. z2. MECHANICAL -- the use of PHYSICAL structures (chewing, grinding) to break the food apart.

Food is broken down in the following structures: zMouth -- MASTICATION -- grinding or chewing of food zSALIVA--watery liquid in mouth that beginsdissolving the food.

Mastication -- Teeth zIncisors -- cutting and food intake action y55 psi zCanines -- ripping and biting (Carnivores and Omnivores only) zPremolars -- grinding action zMolars -- grinding action y200 psi

Esophagus zthe muscular tube connecting the MOUTH with the STOMACH zPERISTALSIS -- the movement of food through the digestive system by a series of muscular contractions yAnalward Peristaltic Movements

Stomach zCompartment used for digestion and storage zCattle and sheep (RUMINANTS) have 4 compartments zHorses and swine (NONRUMINANTS) have 1 compartment

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

Small Intestine zmost of the food nutrients are absorbed into the blood here zThe small intestine is very LONG and contains many small folds called VILLI which increase the surface area for more absorption. zThree parts yDuodenum, Jejunum, Illeum

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

Removal of Undigested Wastes zNot all of the food eaten can be digested and absorbed. zAfter most of the water is absorbed, waste is removed from the body through the anus or vent.

Other organs that assist in digestion zliver -- stores carbohydrates (glycogen), detoxifies blood, produces bile zpancreas -- produces insulin and pancreatic juice zgall bladder -- stores bile until it is needed

Terminology of feed as it moves through the system zFeed or Feedstuff zIngesta zCud zChyme zDigestive End Products (DEP’s) zFecal Material or Non-Digested End Products zFeces

The GI tract -- Descending zOral cavity (mouth) zIncisors zMolars zEsophagus zStomach y1 compartment, or y4 compartments z Small Intestine yDuodenum yJejunum yIlleum z Cecum z Large Intestine (Colon) z Rectum z Anus

Enzymes and Chemicals Name of EnzymeType of food broken downWhat the food Becomes Amylase Starch (carbohydrates)Disaccarides (carbohydrates) Lipase Lipids (fats)Fatty acids Maltase Maltose (carbohydrates)Glucose Lactase Lactose (carbohydrates)glucose and galactose Pepsin Proteinpeptides Peptidase peptidesamino acids Trypsin proteinpeptides Sucrase sucroseglucose and fructose Name of ChemicalWhere ProducedEnzymes Contained Gastric Juice Lining of the stomachhydrochloric acid, pepsin Bile Liver (stored in gall bladder)Lipase Pancreatic Juice PancreasLipase, trypsin, amylase Intestinal Juice Lining of the small intestineSucrase, Maltase, Peptidase, Lactase

Ruminant Digestive System zCattle and sheep have a RUMINANT digestive system. zThis means that their stomachs have FOUR compartments. zThe first of these compartments contains many MICROORGANISMS that help break down CELLULOSE.

Ruminant Digestive System zCellulose -- a substance found in the cell walls of plants. It cannot be used unless it is first broken down fermented) by microorganisms.

Ruminant Digestive System zTwo types of Microorganisms zBacteria -- digest and ferment readily available carbohydrates; digest and ferment the cellulose and hemicellulose part of feed. zProtozoa -- store readily available carbohydrates; produce protein; ferment cellulose material

Ruminant Digestive System zRegurgitation -- ruminants consume large amounts of roughage. It is first chewed just enough to swallow it. zAfter they consume the food, they REGURGITATE it, or force it back into the mouth, so that it can be chewed again. (Chewing CUD).

Ruminant Digestive System z4 parts of a ruminant stomach zRumen -- the largest compartment; stores and ferments the feed zReticulum -- foreign particles (nails, wire) are removed zOmasum -- eliminates water from the feed zAbomasum (true stomach) -- gastric juice is secreted;feed is broken down

Ruminant Digestive System

Monogastric Digestive System zMonogastric Digestive System zSwine, dogs, bears and humans have only one stomach. These animals cannot digest cellulose.

Monogastric Digestive System

Modified Monogastric System zModified Monogastric System zHorses and rabbits have only one stomach, but have structures that contain microorganisms so they can digest cellulose. zMicroorganisms are found in the cecum and in the large intestine.

Modified Monogastric System

Avian Digestive System zBirds (Turkeys, Chickens and pigeons) have structures not found in other species that allow them to digest shells of seeds and other hard foods.

Avian Digestive System zCrop -- a storage organ that holds food until it can be digested zGizzard -- grinds the food zCloaca -- the cavity just before the vent that collectsundigested wastes, uric acid (instead of urine -- high in nitrogen), and reproductive cells.

Avian Digestive System