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(vertebrate zoology)
The final chamber of the complex stomach of ruminants; has a glandular wall and corresponds to a true stomach.



the fourth and last part of the multicompartmental stomach of ruminants, corresponding to the simple uncompartmental stomach of most mammals. The abomasum is connected to the omasum (third stomach) and the duodenum. The mucous membrane of the abomasum is covered by prismatic epithelium and contains fundic, pyloric, and cardiac glands. It forms 13 or 14 long folds, which enlarge its surface. In young animals the mucous membrane of the abomasum produces rennin. The muscular membrane of the abomasum consists of external longitudinal and internal circular layers. Food is digested in the abomasum by gastric juice.

References in periodicals archive ?
The reasons for this are a) selective filtering by the mat, a thick mass of partially degraded, fibrous material that is formed in the rumen, in combination with ruminal contractions, and b) smaller particles are better able to pass through the orifice, the opening between the reticulorumen and the abomasums, than larger particles (Poppi et al.
Infusion of long-chain fatty acids varying in saturation and chain length into the abomasum of lactating dairy cows.
1967) A new method for the cannulation of the abomasum in sheep.
Nutritional Risk Factors in the Etiology of Left Displaced Abomasum in Dairy Cows: A Review.
Ruminants are a type of animal with a four-chambered stomach that includes the reticulum, rumen, omasum, and abomasum (Figure 5-9).
Having just studied bovine anatomy in a veterinary technology program, I'd like to point out that the order of the four stomachs of the cow (from esophagus to small intestine) are: 1: Reticulum (the honeycombed texture); 2: Rumen (actually has a texture similar to short pile chenile and is called papillae); 3: Omasum (the folds); and 4: Abomasum (mucous-lined and most similar to what a human stomach would look like).
By removing water and passing on a drier feed material, the omasum allows the secretions of the following chamber, the abomasum or true stomach, to be more effective in digestion.
Ashworthius patriciapillitae Hoberg, Abrams, Carreno and Lichtenfels, 2002 Abomasum, Odocoileus virginianus (M), Parque Nacional Santa Rosa, Guanacaste (Carreno et al.
In cattle unmasticated whole grains which are those still resistant to enzyme attack are able to pass from the reticulo-rumen into the abomasum, whereas in sheep or goats similar grains are retained within the reticulorumen and subjected to further mastication during rumination, which results in rupture of the seed coat of most of the cereal grains, so enzyme degradation can occur (Nordin and Campling, 1976).
All 22 carcasses showed evidence of malnourishment and starvation: rocks in the abomasum, lack of visceral and body fat, and serous atrophy of bone marrow.
Hindgut fermentation following hydrochloric acid exposure in the abomasum facilitates hemicellulose digestion.