The abomasum, also known as the maw, rennet-bag, or reed tripe, is the fourth and final stomach compartment in ruminants. It secretes rennet, which is used in cheese creation.It is very important and it is the last part of the stomach .
The abomasum's normal anatomical location is along ventral midline. It is a secretory stomach similar in anatomy and function as the monogastric stomach. It serves primarily in the acid hydrolysis of microbial and dietary protein, preparing these protein sources for further digestion and absorption in the small intestine.
Dairy cattle on high production diets are susceptible to a number of pathologies, most commonly after calving. A gas filled abomasum can move into an abnormal location resulting in left displaced abomasum (LDA) or right displaced abomasum (RDA). If the abomasum displaces to the right, it is at risk of torsion and becoming a right torsioned abomasum (RTA). A displaced abomasum will cause cows to present all or some of the following signs: loss of appetite, decrease rumen contractions, decrease cud chewing, and drop in milk production. While an LDA and RDA are not immediately life threatening, veterinary care is required for surgical correction. Abomasitis is a relatively rare, but serious, disease of the abomasum whose causes are currently unknown.
The abomasum is used to make the lampredotto, a typical dish of Florence. It is also fried and eaten with onions as part of the Korean dish Makchang gui. Another dish made with the abomasum is Turkish Şırdan.