Published online by Cambridge University Press: 02 September 2010
1. The experiment involved four pairs of Jersey cows in a double reversal trial with two treatments.
2. The control and acetate treatments involved iso-caloric concentrate mixtures together with hay. The concentrates and hay were given in constant ratio of 3 : 1 and total feed intake was regulated according to milk yield. Cows on the acetate treatment received a dilute solution of fatty acids (1·7 % w/w) and an all-cereal concentrate mixture; those on the control diet received water and a concentrate containing 10% groundnut meal. The dilute solution of fatty acids provided approximately 31 % of the total digestible crude protein intake as ammonia-N, and 208 g acetate and 34 g propionate per day.
3. The two treatments gave similar dry-matter intakes. The acetate treatment caused a slight and significant depression of milk yield but the fat content of the milk and fat-corrected milk yield were slightly increased by treatment, though not significantly so. The results have been discussed with reference to the end products of digestion in the rumen and role of ammonia-N as a substitute for protein-N.