Poultry Biology - Raising Poultry - page 54

Upon leaving the gizzard, food enters the small intestine and mixes with digestive
secretions from the liver and pancreas. The enzymes produced in the wall of the small
intestine aid in the digestion of proteins and sugars. Absorption of the nutrients into the
bloodstream takes place in the small intestine prior to food entering the large intestine.
The point where the small and large intestine meet is where the ceca are located. These
are two dead-end sacs in which some additional bacterial digestion takes place, but little
is known of their function. Animal scientists do know that these cecal pouches are the
first place to look when checking for the parasitic sporazoan disease coccidiosis and oth-
er diseases during an autopsy.
The large intestine in birds is very short — only about 4 inches (10 cm) long — and
is about twice the diameter of the small intestine. It is here that water reabsorption takes
place and body fluid balance is maintained. The end of the intestine is called the cloaca.
Cloaca means “sewer” in Latin; this name is fitting, as the cloaca is the area where the
digestive, urinary, and reproductive systems all empty into the vent, the external open-
ing at the rear of the body.
In addition to aiding in digestion, the liver also detoxifies blood and manufactures
uric acid, which is later filtered out by the kidneys. Uric acid mixes in with the feces
and is the white product in bird droppings. Remember, chickens do not have a urinary
bladder and do not store urine.
The kidneys filter, absorb, and excrete. They filter water and some other substances
along with waste products of metabolism. They conserve water and produce the enzyme
renin , which helps regulate blood pressure and synthesizes metabolites of vitamin D to
aid in the absorption of calcium for eggshell and bone formation.