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Digestive System of the Chicken


Courstesy of the University of Kentucky College of Agriculture

The primary components of the Digestive System of the Chicken are the Ceca, Crop, Dudenal Loop, Esophagus, Intestine (large and small), Gall Bladder, Gizzard, Liver, Mesentary, Pancreas, and Proventriculus.  The flow of ingested material through the chicken is the mouth to the esophagus to the crop to the proventriculus, to the gizzard to the small intestine to the large intestine where the resulting feces is mixed with uric acid and passed out the vent.

Ceca - the ceca is a pouch or sac that is located where the large and small intestine come together.  In the chicken there are two of them collectively called the cecum.  They contain microorganisms that allow chickens to digest fiber via fermentation by these microorganisms.

Crop - the crop is a large temporary storage space for ingested materials.

Duodenal Loop - often referred to as the duodenum, the duodenal loop is the upper part of the small intestine.

Esophagus - the esophagus is the the long tube that is responsible for moving ingested material from the mouth to the stomach.


Small - ingested material passes from the stomach through the gizzard and into the small intestine.  Here, additional enzymes are added and digestion occurs by absorption of Carbohydrates, proteins, and fats. In order for proper absorption of digested feed, the small intestine is very long and often measures 4 to 5 feet in length.

Large - the large intestine stores undigested waste material and absorbs water from the material. The large intestine connects to the cloaca, which is where the digestive, urinary, and reproductive systems meet. Uric acid is mixed with feces and passes out of the vent. The vent is also the point where eggs are expelled from the body.  Unlike the samll intestine, the large intestine is very short and is typically only 3 to 5 inches in length. 

Gall Bladder - the gall bladder acts as a storage vessicle for the bile.  The gall bladder connects to the duodenal loop (see duodenal loop above) via a duct called the cystic duct.  These bile acids are used in the brak down and utilization (metabolism) of fat.

Gizzard - the gizzard is a chamber that receives ingested material from the proventriculus.  It has very strong muscular walls that function to mechanically grind the ingested material.   Chickens often swallow small stones as they scratch the ground and consume insects and seeds.  These small stones are used in the gizzard to further grind ingested materials.

Liver - the liver of the chicken consists of two lobes --- a right lobe and a left lobe. The liver has a very important role in maintaining health and productivity through its intricate involvement in digestive, metabolic and excretory activities.  In addition to being a vital part of carbohydrate, protein, fat, mineral and vitamin metabolism, the liver performs a vital function in the detoxification of ingested materials as well as detoxification of toxins produced by the body.  The liver is also responsible for the formation of red blood cells through a process called erythropoiesis.

Mesentary -the mesentary is simply connective tissue that both supports and protects the small intestine; especially the nerves and blood supply of the small intestine.

Pancreas - the pancreas is reponsible for the secretion of digestive enzymes into the small intestine at the point where the small intestine loops around the pancreas.  This loop is called the duodenal loop (see duodenal loop above). 

Proventriculus - the proventriculus is a glandualar organ that secretes acid and enzymes.  It is the stomach of the chicken.  The acid and enzymes are mixed with the ingested materail to start the digestive process.