The absorption of ammonia from the rumen of the sheep

Abstract

Ammonia occurs only in traces, if at all, in the blood of the general circulation of the sheep while the venous blood draining the rumen contains about 1.5 mg. ammonia N/100 ml.; it is concluded that ammonia is absorbed from the rumen. Addition of a soln. of ammonium acetate to the rumen after removal of the ingesta produces a prompt rise in the level of ammonia in the blood draining the organ. It is calculated that the quantity of ammonia N absorbed from the rumen may be of the order of 4-5 g. per day. Urea occurs in significant quantities in the saliva of the sheep. Attention is drawn to the circulation of N in the normal digestive process, viz., urea in saliva is converted in the rumen into ammonia, which may be absorbed into the portal blood stream and converted by the liver to urea, which again becomes available for secretion in the saliva. Ammonia derived from the deamination of proteins in the feed contributes an important fraction of the N of the ruminal ingesta.