Metabolism of nitrogenous compounds in the large intestine of sheep.

I . The deamination, ureolytic and proteolytic activities and rates of cellulolysis and gas production in large intestinal contents have been compared with those activities and rates in rumen contents of sheep. 2. Large intestinal contents produced ammonia. The rate of ammonia production was greater in caecal contents than in faeces. Incubation of caecal contents under toluene resulted in decreased production of ammonia and volatile fatty acids and an increase in the concentration of a-amino nitrogen. 3. Proteolytic activity of large intestinal contents was much greater than that of rumen contents. There was little difference in proteolytic activity between caecal or faecal contents and their liquors whereas the activity in rumen whole contents was greater than in rumen liquor. Some proteolytic activity was present in caecal and faecal cell-free liquors but none was present in rumen cell-free liquor. 4. Deaminase activity was greater in rumen than in caecal contents or faeces. The activity in rumen liquor was less than half that in rumen whole contents. 5 . Urease activity of caecal contents was less than that of faeces or of rumen contents. 6. The rate of gas production in rumen contents was less than that in caecal contents. The rate in faeces was low. Less gas was produced in rumen liquor than in rumen contents, whereas there was little difference between rates in caecal liquor and whole contents. 7. Rates of breakdown of cellulose in vivo were similar in the rumen and the caecum.