The role of ammonia in ruminal digestion of protein

Abstract

In the rumen fluid of sheep, ammonia constitutes the main component of the non-protein N, when the animal is fed natural diets or a diet in which casein is the main source of N. The insoluble protein, zein, is only slowly digested in the rumen. Indirect evidence suggests that ammonia represents an important intermediate in the digestion of dietary protein and its utilization by the symbiotic micro-organisms of the rumen for their growth. The implications of these observations on the role of micro-organisms in the digestion of protein in the rumen are discussed.