Ovarian responses of anestrous ewes to the "ram effect"

Abstract

Ovarian responses to the "ram effect" were characterized in 11 anestrous Corriedale ewes. In seven ewes, there was a luteinizing hormone (LH) surge 36.7 ± 12.3 h (mean ± SEM) after ram introduction and a concurrent increase (P < 0.05) in serum follicle stimulating hormone (FSH). Ovarian responses (monitored ultrasonographically) were highly variable. One ewe had two luteal phases (short and normal, respectively), three had delayed ovulation (days 5-7), two had luteinization of non-ovulatory follicles, one developed a luteinized follicular cyst, and four had no luteal phase.