EFFECT OF BUSERELIN ON PREGNANCY RATES IN DAIRY-COWS

Three field trials were carried out to assess the effect of buserelin on the fertility of dairy cows. In the first, 10 mu g of buserelin was injected on the day of insemination; there were no significant effects on fertility in comparison with untreated control cows. In the second study the cows were injected 12 days after insemination; the mean pregnancy rates to first insemination were 53.4 and 65.4 per cent for the control and treated cows, respectively (P<0.01) and the mean pregnancy rates to repeat inseminations were 52.9 and 59.4 per cent for the control and treated cows. The mean calving to conception intervals were 91.4 and 85.3 days (P<0.01) and the incidences of barren cows were 10.2 and 5.2 per cent. In the third study the cows were injected with buserelin either eight days or 10 days after insemination; there were no significant effects on fertility in comparison with untreated control cows.