EFFECTS OF DIFFERENT NUTRITIONAL LEVELS PREPARTUM ON THE SUBSEQUENT PERFORMANCE OF DAIRY-COWS

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 compris ing altogether 63 multiparous cows. In Experiment I, 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. r estricted) were practiced throughout the experiment. The feeds (concen trate, 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 a verage 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 hig h serum free fatty acids concentrations around parturition. Ad libitum feeding did not result in higher milk yield but gave a greater milk p rotein content and yield and also impaired feed efficiency. Health, fe rtility, and plasma glucose concentrations did not differ between trea tments. (C) 1998 Elsevier Science B.V.