[What possibilities does the milk-progesterone test in dairy cattle offer in clinical practice?]

A field trial was made by the Animal Health Service Foundation in Boxtel, the Netherlands, during the period from December 1984 to June 1985 for the purpose of studying the possibilities of the milk progesterone test (MPT) in dairy cattle in the field. Approximately 10,000 milk samples were taken to determine the concentration of progesterone; this was done daily using the EIA method in the laboratory of the Animal Health Service Foundation in Boxtel. The MPT offers more possibilities in the field than do the detection of oestrus and diagnosis of gestation alone. Experimental studies in eighty-six cows showed that the progesterone levels of the milk start to decrease from a few days prior to oestrus, which means that heat is predictable. The time of insemination is also more or less predictable on the basis of the MPT. It was shown that the concentration of progesterone in the milk of animals subsequently found to be pregnant was less than 1.0 ng/ml on the day of insemination. Optimum results of fertilisation are obtained after the first, second or third day on which the concentration of progesterone in the milk is less than 1.0 ng/ml.