Digestion in the intestines
The digestive content passes from the abomasums into the duodenum as a jet at intervals of two minutes on average. This change is permanent and it causes the continuous secretion of bile and pancreatic juice. In the small intestine occur the digestion and absorption mechanisms, especially for lipids and proteins.
The lipids emulsified by bile salts come in contact with the duodenum lipases that cleave into monoglycerides and fatty acids. Fatty acids with short chain are absorbed directly through the mucosa of the small intestine and are transported through the bloodstream. Monoglycerides and fatty acids with long chain are emulsified by bile salts to form micelles. Once they are inside the cells of the intestinal mucosa, fatty acids with long chain are reesterified, forming triglycerides, which then reach the lymphatic circulatory system in the form of chylomicrons.
The final products of the protein digestion are adsorbed either in the form of amino acids, either in the form of dipeptides and tripeptides, which, afterwards, are hydrolyzed into amino acids in the absorptive cells of the intestine. Finally, only free amino acids leave the absorbing cells to be discharged into the blood and conducted to the liver.
Water is absorbed in combinations, especially with mineral salts.
Water-soluble vitamins, especially those from the B complex, are absorbed simultaneously with electrolyte solutions, and fat-soluble vitamins are absorbed simultaneously with the lipids.
The remaining from the digestion in the small intestine arrive intermittently into the large intestine where they remain 15 to 24 hours. The secretion of enzymes lacks, but the remaining is subjected to fermentation processes similar to those from the rumen.
In the large intestine, at the cecum level are absorbed excess VFA and the ammonia produced in excess and in the colon are absorbed the water and mineral substances.
