Digestion of protein in the reticulon-rumen

• Food proteins of plant and animal origin are hydrolyzed to polypeptides and then to smaller peptides and amino acids by extracellular microbial proteases.
• The amino acids are degraded further by intracellular microbial deaminases to ammonia organic acids and CO2.
• The ammonia produced together with small peptides and amino acids is utilized by rumen microorganisms to synthesize microbial proteins.
• NPN sources also readily degraded in the rumen to ammonia and then to microbial protein.
• After this when the organisms are carried through to the abomasum and small intestine they will be digested by the proteolytic enzymes of the host and absorbed as amino acids.
• If the animal is supplied with excess nitrogen, there will be excess ammonia production which will be converted to urea in the liver and the animal has a mechanism to remove excess urea by excreting it in the urine.