METABOLIC BALANCE AND REPRODUCTIVE-PERFORMANCE IN FINNISH DAIRY-COWS

The relationships between energy level and reproductive performance were studied in 24 dairy cows, which were fed grass silage. Serum glucose and blood acetoacetate (AA) and β‐hydroxybutyrate (HB) were measured 10, 15, 30 and 50 days postpartum. The cows were examined clinically by rectal palpation 3 times a week during 8 weeks postpartum. The time required for the complete uterine involution and the onset of ovarian activity were recorded. The pregnancy rate at the first insemination and the interval from calving to conception were obtained for each cow. The correlations between blood glucose and ketone bodies were negative, but they were significant only at days 15 and 30 for AA and at day 30 for HB. A low energy level in early puerperium caused a delay in uterine involution and in the onset of ovarian activity. The low energy balance in puerperium prolonged the interval from calving to the first insemination and the interval from calving; to conception. The earlier the ovarian activity started the shorter was the interval from calving to conception. The energy level in early puerperium had a greater influence on the interval from calving to conception, whereas in late puerperium it was more important with regard to the interval from calving to the first insemination. Blood glucose had also a significant effect on the reproductive performance. The adverse influence of ketone bodies on fertility depended on duration and timing of their increased levels; the longer and later in puerperium the cow has elevated ketone bodies, the lower is the fertility. Cows which had increased ketone body levels at day 50 were inseminated later, had a longer interval from calving to conception and needed more inseminations per conception than the non‐ketotic animals. If shorter calving intervals are desired, adequate nutrition is essential after calving. © 1990 Blackwell Verlag GmbH