Effect of nutrition of dairy cows in late pregnancy on milk production

Three experiments were carried out to examine the separate effects of rate of liveweight gain in late pregnancy and of body weight of cows at calving on subsequent milk production. In each experiment, cows were allocated to one of two treatments about 12 weeks before calving. They were then fed so that by six weeks before calving there was a difference of about 50 kg liveweight between the animals in the two groups. In the first experiment, the two groups were then fed to gain weight at either 1.0 or 0.5 kg day-l so as to calve in similar body condition. In the second experiment, the two groups were fed to gain 1.5 kg day-1 or maintain weight so that again they calved in similar condition. In the third experiment both groups had similar rates of liveweight gain, 0.7 kg day-1 in the last six weeks of pregnancy, so that there was a difference of 51 kg at calving. In the first two experiments there were no differences due to the contrasting pre-calving nutrition in the milk production of the two groups, but in the third experiment the cows calving with the heavier body condition had a 7% greater milk yield and a higher milk fat concentration in the first 100 days of lactation. The results demonstrate that body condition of cows at calving is the important factor affecting milk production and that liveweight trends per se prior to calving were unimportant in influencing subsequent milk production. These findings offer dairy farmers alternative choices of feeding and grazing management strategies to improve cow condition at any stage during the dry period.