Dehydroepiandrosterone and epitestosterone in the blood of cows at term.

From Day 268 of gestation till two days after parturition blood samples were collected from the jugular vein of 5 cows with normal and 4 cows with flumethasone induced parturition and centrifuged immediately after sampling. In another experiment blood samples were taken from the jugular and uterine vein of 3 cows during the last week before normal parturition. The dehydroepiandrosterone (DHA) and epitestosterone (ET) concentrations in plasma were measured using radioimmunoassay. In the control group the DHA concentration was in the range of 2 to 5 nmol/l, ET levels varied from 4 to 8 nmol/l before term. In both groups, there was an increase in DHA concentrations during the last periparturient period whereas ET levels increased only after flumethasone induced parturition. The concentrations of both androgens declined after the expulsion of the placenta and they were higher in the uterine vein than in the jugular vein. It is concluded, that both androgens are secreted by the bovine placenta and that the delta 5-pathway of steroidogenesis is active in vivo.