[Early diagnosis of pregnancy in the cow as assessed by milk ejection induced by luteal oxytocin].

The diagnosis of pregnancy described in this article is based on the observation of milk ejection which, in the case of corpus luteum maintenance, results from the release of luteal oxytocin induced by intravenous administration of a non luteolytic dose of PGF2 alpha. The tests were performed in 410 lactating cows, 18-22 days after insemination (mean 19.95 days, SD 0.

[Influence of undernutrition in the lactating cow on ovulation induction by serum gonadotropins (PMSG) during the post-partum period].

Two experiments were carried out to assess the influence of undernutrition on postpartum ovulation in nursing Charolais cows after PMSG injection. In each experiment, the nursing cows were divided into 2 groups: one fed at a low nutritional level and the other at a normal nutritional level. In the first experiment, 19 animals were injected on post-partum days 15 and 30 with 600 IU of PMSG; in the second experiment, 34 received the same injection on post-partum day 54 after 9 days of priming with a Norgestomet implant.