Protein Metabolism in the Rumen

• Proteins are hydrolyzed by the bacteria protozoa and anaerobic fungi of these three groups of bacteria are most important one.
• The main function of protozoa appears to be the metabolism of bacterial protein rather than the hydrolysis of dilatory proteins (Exogenous proteins).

• Urea enters the rumen in feeds; in saliva and by direct translocation from the blood, approach the rumen wall.
• Urease is produced in small amounts by a no. of oligates and facultative anaerobic bacterial species.
• Ammonia is produced during microbial metabolism of diverse substrates & is a major source of Nitrogen used for the bio synthesis of bacterial protein e.g. Glutamate dehydrogenase and Glutamine synthetase are the bacteria enzymes that are most important for ammonia assimilation.
• Of these two, enzyme glutamine synthetase has the higher affinity for ammonia (because it is good assimilator of ammonia than another as NH3 is toxic), so it is probably more important when ammonia level is lower.
• When starch soluble sugar are present in excess, no. Of species of protozoa rapidly assimilates the carbohydrates and incorporate them into intracellular reserve polysaccharides.
• A favorable function is thus served by protozoa by competing with lactic acid producing bacteria (Streptococcus bovis, different spp. of Lactobacillus).