Invasive Species Compendium

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Abstract

Time of ovulation in goats (Capra hircus) induced to superovulate with PMSG.

Abstract

The timing of ovulation in feral goats treated with 1200 IU PMSG with or without 50 µg GnRH was studied by repeated laparoscopy. Experiment 1 established that superovulation began as early as 30 h after withdrawal of progestogen-impregnated sponges and was not completed at 54 h if goats received PMSG alone. GnRH synchronized ovulation, leading to 91% of ovulations appearing between 36 and 48 h after sponge removal. Experiment 2 established that superovulation continued up to 77 h after treatment in goats receiving only PMSG. The stress of repeated laparoscopy appeared to delay or abolish ovulation in some ♀♀. The mean ovulation rate was 12.7±1.3 in goats treated with GnRH vs. 9.7±1.1 in those that received PMSG only (P<0.05). Of 47 of the ♀♀ in the 1st experiment, 43 had ≥1 corpora lutea at laparoscopy 24 h after withdrawal of progestogen. These early corpora lutea were associated with an increased plasma progesterone concentration during the periovulatory period. Experiment 3 provided evidence that these corpora lutea arose before the withdrawal of progestogen-impregnated sponges.