Effects of different nutritional levels prepartum on the subsequent performance of dairy cows

Abstract

Different nutritional levels introduced three weeks before calving and gradually reaching the maximum supply level of 110, 170, 200 or >200 (ad lib) MJ ME/day at calving were studied in two experiments comprising altogether 63 multiparous cows. In Experiment 1, the difference at calving (110 vs. 200 MJ) was gradually eliminated within 4 weeks post partum, while in Experiment 2 treatment differences (ad libitum vs. restricted) were practiced throughout the experiment. The feeds (concentrate, grass hay and grass silage) were fed separately in Experiment 1 and as a total mixed ration in Experiment 2. The experimental period lasted from 4 weeks before calving to 12 or 14 weeks afterwards. The average daily intake of metabolizable energy in cows fed ad libitum was 180 MJ prepartum and 307 MJ in early lactation. A marked decrease in feed intake occurred around calving time, beginning 3–5 days prepartum, among all cows fed a medium or highly nutritional diet at calving. A low nutritional level at calving resulted in a significantly smaller milk yield in the first month postpartum and low serum insulin and high serum free fatty acids concentrations around parturition. Ad libitum feeding did not result in higher milk yield but gave a greater milk protein content and yield and also impaired feed efficiency. Health, fertility, and plasma glucose concentrations did not differ between treatments.