[Improvement of fertility status in dairy farms by using the milk progesterone test]

On nine farms comprising a total number of 370 cows, studies were done for two years to determine whether the reproductive status (RS) could be improved by systematic performance of the milk progesterone test. Milk samples were taken on the day of insemination (day 0), day 8 and day 21 to verify oestrus detection, the observation of ovarian dysfunction and the early diagnosis of (non-)pregnancy. The RS on these nine farms increased from thirty-six to fifty-four, which was mainly due to the reduction of the number of inseminations required for each conception (from 2.1 to 1.7). On ten farms selected by a similar method, on which reproduction was supervised by the veterinary practitioner, the RS increased from forty-seven to fifty-five, which increase was particularly due to inseminations carried out sooner after calving. The RS of ten herds which served as controls, increased from forty-one to forty-seven. An analysis of costs showed that the costs using the progesterone test were estimated to be equivalent to the expense of supervising a reproductive dairy herd health programme. A diagnosis negative for pregnancy based on three milk samples tested was correct in 98 per cent of the cases. A diagnosis positive for pregnancy was correct in 90 per cent of the cases. When a death rate of 8 per cent of the embryos within three weeks after conception is taken into account, the proportion will also be 98 per cent. Summarizing, it is concluded that systematic performance of the milk progesterone test provides an attractive method of improving reproduction on those farms which do not take part in veterinary supervision of reproductive dairy herd health programmes.