Animal Digestion

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.

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

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.

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

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.

Types of Digestive Systems Ruminant Monogastric Pseudo-Ruminant Avian

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

Types of Digestive Systems

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

Types of Digestive Systems

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.

Types of Digestive Systems

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.

Types of Digestive Systems

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

Digestive System Functions

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

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

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.

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.

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 60 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.

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.

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

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.

Digestive System Functions Small Intestine

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

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.

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

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

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.

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.