Feeding high energy supplements to pasture-fed dairy cows. Effects of stage of lactation and level of supplement
1987
Stockdale, C.R. | Callaghan, A. | Trigg, T.E. (Victorian Dept. of Agriculture and Rural Affairs, Kyabram (Australia). Animal and Irriagted Pastures Research Inst.)
5 experiments were done in which stall-fed dairy cows at various lactation stages were provided with a basal ration of pasture which was supplemented with varying amounts of a pelleted, high energy supplement. Marginal responses in milk production fell as lactation progressed, and as the level of feeding increased. Responses in milk fat yield also decreased as lactation advanced. There was a reduction in milk fat production when more than about 6 kg DM of supplement were fed. This was due to a severe depression in the fat content of the milk, which was found to be associated with intakes of diets of ratios of lipogenic to glucogenic volatile fatty acids in the rumen below 4:1. This occurred when the supplement constituted 0.4-0.5 of the diet on a dry matter basis. In addition, rumen ammonia levels were low when large amounts of supplement were fed. With all rumen characteristics, stage of lactation had no influence on values.
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