Responses in milk yield and composition to the inclusion of ammonium salts of short-chain fatty acids in the drinking water of dairy cows

Abstract

SUMMARYThe effect of introducing a solution of fatty acids (consisting mainly of ammonium acetate) into the drinking water of Jersey and Friesian cows on the yield and composition of milk was investigated. In short-term experiments there were small increases in milk yield and in the yield of fat in Jersey cows receiving either a high-roughage or a high-concentrate diet and in Friesian cows receiving a high-concentrate diet. Friesian cows receiving a high-roughage diet gave no response. In a long-term experiment extending over 16 weeks of lactation with Jersey cows receiving a high-concentrate diet, there was no immediate effect on milk yield but a greater persistency and overall the yield of fat was increased by 5·9%.Inclusion of ammonia salts in the drinking water caused increases in the ammonia contents of rumen liquor and of blood but there was little effect on rumen pH or the volatile fatty acids of rumen liquor.