Detection of ovulation in goats by blood prostaglandins concentrations

Eighteen mature female goats of nondescript breed were randomly assigned equally to 3 treatment groups. Group I goats served as controls, group II goats were treated (IV) with a single dose of 300 micrograms of synthetic luteinizing hormone-releasing hormone (LHRH); group III goats were treated with LHRH (similar to group II) and 24 hours later were given indomethacin (10 mg/kg; IM) which dosing was repeated every 6 hours for the next 90 hours. Blood samples were collected from all animals every 6 hours until 120 hours and assayed for prostaglandin E (PGE) and PGF2 alpha. On days 7 and 8, the animals were surgically laparotomized to observe the ovarian activity. In groups I and III goats, there was no evidence of follicular development or ovulation, but in 4 of the 6 group II goats, there were ovulatory points or corpus luteum. Mean plasma PGE and PGF2 alpha concentrations in control goats did not vary significantly (P less than or equal to 0.05) during the sampling period; but in the LHRH-treated goats (group II), these concentrations peaked twice--a low peak at 24 hours and a sharp peak at 78 to 90 hours. In contrast, these concentrations in group III goats (LHRH plus indomethacin) dropped sharply in the control group (I) value after reaching the 1st peak, and then stayed at this low plateau for the remainder of the sampling period; the 2nd peak was absent. The results indicate that the ovulation could be induced by LHRH injection in anestrus goats and that ovulation is preceded by a marked increase of plasma PGE and PGF2 alpha concentrations.