Plasma levels of LH, FSH, prolactin, oestradiol-17beta and progesterone during natural and induced oestrus in the dairy goat.

The patterns of LH, FSH, prolactin and oestradiol-17beta, before and during natural oestrus, and of progesterone during the following cycle were studied in four French Alpine dairy goats and compared with those obtained after synchronization of oestrus in the same animals. The highest concentration of oestradiol-17beta was measured at the beginning of oestrus and was followed 3 hours later by simultaneous rises of LH, FSH and prolactin. A second FSH peak was observed 48h after the first one. On D(3) (D(0) = day of oestrus) progesterone concentration was over 1 ng/ml. The luteal phase lasted 15 days. Peak concentrations of oestradiol-17beta and progesterone were higher in animals when oestrus was induced. This was attributed to their higher ovulation rate. The second FSH peak was lower, and the interval between oestradiol-17beta peak and gonadotrophin surge longer, than at natural oestrus.