Use of the Milk Progesterone Test for Pregnancy Determination

Abstract

SUMMARY A pregnancy testing service using the milk progesterone test has been available to dairy farmers in the United Kingdom since 1975. After three years operation, more than 100 000 cows a year are being tested and 5.6% of the farmers in England and Wales are using the service. The service is used proportionately more in larger herds (median herd size is 76 cows) and in autumn-calving herds. The percentage of negative tests rose to 20.0% in the third year, although there was considerable seasonal variation. A sample of large herds using the service found average accuracy rates of 84.5% and 97.0% respectively for positive and negative tests. A highly significant correlation ( r = + 0.84) was found between the proportion of positive tests in a herd and the accuracy rate of these tests. These two factors, and analysis of insemination interval data, are good indicators of herds requiring veterinary investigation.