THE ESTIMATION OF THE ENERGY VALUE OF LIVEWEIGHT CHANGE IN THE LACTATING DAIRY COW

Abstract Nine feeding experiments with dairy cows have been combined to assess liveweight change and its energy value at two stages of lactation. All animals were individually fed. Records of group average food intakes, milk yields and composition, and liveweights were available. Mean metabolisable energy (ME) intakes were calculated and estimates of energy balance (EB) derived by difference between ME intake and the ME requirement for maintenance and milk production according to the Ministry of Agriculture, Food and Fisheries (MAFF). Mean EB was regressed on mean liveweight change (LW) and highly significant ( P In mid lactation, when mean A W was small and positive, no significant relationship was found for heifers, but for cows a significant relationship ( P