Understand the digestive process. Objective 7.02

Digestive Terminology Digestion- the process of breaking feed down into simple substances that can be absorbed by the body. Digestive System- the parts of the body involved in chewing and digesting feed. Absorption- the process of taking digested parts of feed into the bloodstream.

Digestive Terminology Ruminants- animal that have a stomach that is divided into several parts. Cattle, goats and sheep are examples of ruminant animals. Ruminant animals can digest larger amounts of roughage material compared to nonruminants. Ruminants do not chew their food completely. Some food is swallowed and then rechewed later through a process known as “chewing the cud.” This process is also called rumination. Nonruminant- animals that have a monogastric or single compartment stomach. Horses, pigs, dogs, cats, and poultry are examples of monogastric animals. Non-ruminants cannot eat and digest as much roughage as ruminants.

Ruminant Digestion Mouth Esophagus Function: Bites and chews food. Breaks food into smaller particles. Saliva present in mouth contains enzymes which speed up the digestive process. Description: Beginning of digestive tract. Includes teeth and tongue. Esophagus Function: Guides food from mouth to stomach with involuntary muscular contractions. Description: pinkish grey colored muscular tube next to trachea. Guides food from mouth to the stomach.

Ruminant Digestion Rumen Reticulum Function: Bacteria change large amounts of roughages into amino acids. Description: Large white/grey colored sac on the left side of the animal. Largest section of the stomach. Interior lining resembles carpet. The rumen and reticulum make up 85% of stomach capacity. Reticulum Function: Take in liquids that soak food for microbial digestion. Description: White/grey colored sac connected to the rumen on the left side of the animal. Interior lining resembles a honeycomb pattern.

Ruminant Digestion Omasum Abomasum Function: Contains papillae responsible for grinding roughage. Description: Round, muscular part of stomach with many layers of tissue that squeezes feed and removes some liquid. Abomasum Function: Enzymes and gastric juices act on feed. The abomasums is the only functional portion of the ruminant’s stomach when animals are born. Description: Elongated sac at the base of the stomach. Interior lining is the smoothest of all stomach parts.

Ruminant Digestion Small Intestine Cecum Anus Function: Partially digested feed is mixed with bile, pancreatic juice and intestinal juice. Most food nutrients are absorbed from the villi (small hairlike projections) in the small intestine. Description: Long coiled tube. Cecum Function: Serves little to no function for most animals. Horses and rabbits and guinea pigs have an enlarged cecum that uses microbial action to break down roughages. Description: A blind pouch located between small and large intestine. Anus Function: Excrete waste. Description: End of digestive tract.

Nonruminant Digestive System Parts and Functions Mouth Function: Bites and chews food. Breaks food into smaller particles. Saliva present in mouth contains enzymes which speed up the digestive process. Description: Beginning of digestive tract. Includes teeth and tongue. Esophagus Function: Guides food from mouth to stomach with involuntary muscular contractions. Description: Pinkish grey colored muscular tube next to trachea. Guides food from mouth to the stomach.

Nonruminant Digestive System Parts and Functions Stomach Function: Enzymes act on feed, churns, and mixes feed. Description: A “U” shaped pinkish/white colored sac connected to the esophagus. Small Intestine Function: Partially digested feed is mixed with bile, pancreatic juice and intestinal juice. Most food nutrients are absorbed from the villi (small hairlike projections) in the small intestine. Description: Long coiled tube.

Nonruminant Digestive System Parts and Functions Cecum Function: Serves little to no function for most animals. Horses, rabbits and guinea pigs have an enlarged cecum that uses microbial action to break down roughages. Description: A blind pouch located between small and large intestine. Large Intestine Function: Absorbs water and adds mucus to the undigested feed to form feces. Description: Coiled tube shorter in length, but larger in diameter than the small intestine. Anus Function: Excrete waste. Description: End of digestive tract.

Ruminant and Nonruminant Digestive System Accessory Organs Liver Function: Produces bile that acts on fats. Description: Dark brown structure made of several lobes. Largest gland in the body, located under the stomach. Pancreas Function: Produces digestive enzymes. Description: Elongated reddish colored organ that lies against the stomach. Gall Bladder Function: Produces bile that aids in digestive process. Description: Sac like structure filled with greenish fluid. Located on the liver.

Poultry Digestive System Parts and Functions Mouth Function: Pecks and takes in feed. Poultry do not have teeth. Description: Yellow pointed structure. Esophagus Function: Guides food from beak to crop. Description: Muscular tube shaped structure. Crop Function: Stores and softens feed from saliva secretions. Description: Oval sac-like structure between esophagus and proventriculus.

Poultry Digestive System Parts and Functions Proventriculus Function: True stomach of chicken, but serves no true function. Description: A wider section of the digestive system compared to esophagus. Gizzard Function: Feed is crushed and mixed with digestive juices. Contains grit and gravel to assist in crushing feed particles. Description: Oval shaped muscular that is purplish in color. Located between the proventriculus and small intestine. Liver Function: Accessory organ that produces bile that acts on fats. Description: Dark red colored organ made up of several lobes. Small Intestine Function: Mixes juices, most food nutrient absorption occurs in small intestine. Description: Long tube like structure.

Poultry Digestive System Parts and Functions Ceca Function: Contain soft, undigested feed, but function is unknown. Description: Unlike other animals, poultry have two ceca. Located between small and large intestine and are “blind” pouches, each are approximately 7 inches in length. Large Intestine Function: Absorbs water and adds mucus to undigested feed, which becomes feces. Description: Tube-like structure large in diameter when compared to small intestine. Filled with digested feed. Cloaca Function: Digestive and reproductive tracts combine and prepare for excretion of waste or eggs. Description: Enlarged part of digestive tract located just before the vent. Vent Function: Excrete solid (feces) and liquid (urine) waste. Description: External opening and the end of the digestive tract.