Ruminants abomasum

Finally, the contents of the omasum, now a thick slurry of microorganisms, pass into the abomasum into which are secreted acid and proteinases to produce an environment corresponding to that of the human stomach. Some of the microflora passing from the rumen to the omasum die and are digested by the acid and the enzymes. This provides the ruminant not only with an additional energy source but with vitamins and essential amino acids that its own tissues caimot synthesise. 

In all species, the small intestine is the main site for simultaneous hydrolysis of fats, proteins, and carbohydrates by selective enzymes and absorption of the resulting nutrients. It consists of three sequential sections duodenum, jejunum and ileum, each with villi and mucosal linings. During the process, the pH of the digesta is raised from that of the stomach, to near neutrality over the length of the small intestine. In swine, the pH profile is as follows stomach, 2.4 proximal duodenum, 6.1 distal duodenum, 6.8 proximal jejunum, 7.4 distal jejunum, 7.4 and ileum, 7.5. In sheep, the profile is abomasum, 2.0 proximal duodenum, 2.5 distal duodenum, 3.5 proximal jejunum, 3.6 distal jejunum, 4.7 and ileum, 8.0 (48). Several types of contractive and peristaltic actions mix and move the digesta down the intestine. The lower pH at the proximal duodenum of ruminants plays a critical part in fatty acid reabsorption. Hydrolysis of triacylglycerols by pancreatic lipase... 

Ruminants include those animals that we normally think of as cud-chewing, or ruminating animals common examples include cattle, sheep, and goats. The most unusual feature of these animals involves their digestive system, and in particular their multi-compartmented stomach. They are commonly referred to as having four stomachs. The true stomach, that part comparable to the stomach of man, is preceded by 3 other compartments. These are, in order, the rumen, reticulum, omasum, and abomasum. 

Fig. 8.5 Diagrammatic representation of the rumen, reticulum, omasum and abomasum of the ruminant, indicating the flow of digesta.

Rumen breakdown of food protein is not always desirable, because microbial protein may be inferior to it in both quantity and quaiity. Thus, food proteins are sometimes protected from attack by rumen microorganisms. in suckled ruminants, there is a device known as the oesophageal groove, which channeis miik directly to the abomasum. 

Although tannins appear to protect protein from microbial attack in the rumen, their ultimate effects on ruminant nutrition may depend upon how available this bypass protein is to the animal. According to Price and Butler (1980), the same factors that cause tannins to have a deleterious effect on monogastric nutrition, will presumably be important in the post-rumen digestive tract. If the tannin-protein complex does not dissociate in the abomasum or intestine, there will be no benefit to the animal from the protein having been protected in the rumen. If it does dissociate, the liberated tannin may damage the intestinal tract or form new complexes at some point with endogenous proteins. 

Rumen hydrogenation, which has been reviewed by Viviani, effects almost complete removal of dietary polyunsaturated acids from the depot and milk fats of ruminants. This may be undesirable from a human viewpoint because of increased interest in dietary polyunsaturated fat, and an Australian group have suggested how this depletion can be avoided. Linseed or safflower or sunflower oils are fed to the animals in capsules of formaldehyde-treated resins which resist breakdown in the rumen but are hydrolysed under the more acidic conditions of the abomasum. By this means the content of polyunsaturated fatty acids in milk and depot fats can be raised from the 2—5% level to around 25—30%. This change requires only 24—48 hours for the milk fat but rather longer for the depot fat. ... 

Abomasum The fourth chamber of the ruminant stomach, also called true stomach. The abomasum secretes digestive enzymes and hydrochloric acid. 

Omasum The third compartment of the ruminant stomach consisting of a spherical organ containing various sized leaves that prevent undigested materials from leaving the rumen and entering the abomasum. It absorbs electrolytes from the bolus. 

Ruminant A mammal that possesses four compartments in the stomach (rumen, reticulum, omasum, abomasum) and is capable of digesting fiber-rich foods. The rumen contains a wide range of anaerobic microorganisms capable of converting cellulose and other fibers—except lignin—into volatile fatty acids that are used as a source of energy. 

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