THE INFLUENCE OF GONADOTROPHIN-RELEASING HORMONE AT ESTRUS ON OVULATION RATE AND THE DEVELOPMENT OF CORPORA LUTEA IN EWES

Abstract

Twenty-two ewes received either 30 μg GnRH or saline at the onset of estrus. Blood samples were obtained on days 1–7 (day 0 = estrus) and corpora lutea recovered surgically at day 7. There was no effect of GnRH on the number or weight of corpora lutea nor on the concentrations of progesterone in either corpora lutea or plasma. GnRH treatment caused an increase (P < 0.07) in luteal hCG binding capacity (0.66 ± 0.12 vs. 0.34 ± 0.12 nmol mg −1 protein). Key words: GnRH, estrus, corpora lutea, hCG binding