OVARIAN RESPONSE AFTER A GNRH CHALLENGE IN SEASONALLY ANESTROUS EWES

To study the ovarian response of seasonally anestrous Corriedale ewes to a gonadotropin releasing hormone challenge, daily transrectal ultra sonography or laparotomy were performed and luteinizing hormone and pr ogesterone profiles were determined. Of the responding ewes (8/17), th ree ovulated and formed a healthy corpus luteum and five formed large luteinized follicular cysts that secreted low progesterone levels for 2 to 3 d. Therefore, the study of progesterone profiles alone could le ad to erroneous interpretations of the ovarian response to GnRH challe nge in sheep.