Importance of non-olfactory ram stimuli in mediating ram-induced ovulation in the ewe

Abstract

In Exp. 1, 4 groups of 50 recently weaned ewes were exposed to various degrees of contact with rams for 65 days, followed by exposure to novel rams for 4 days. Ovarian activity in the ewes was determined by laparoscopy on Days 29, 65 and 69 of treatment. There were no treatment differences in the percentage of ewes ovulating on Day 4 whereas by Day 29 more ewes in clear fenceline and full ram contact were ovulating compared to controls (P less than 0.05, P less than 0.001). After 65 days ovarian activity was significant only in those ewes in full contact with rams (P less than 0.001). Between 89 and 95% of ewes remaining anovulatory after 65 days ovulated after 4 days of full contact with novel rams. In Exp. 2, 4 groups of about 30 anovulatory ewes were exposed to various degrees of contact with rams for 5 days. Ovarian activity was assessed before and after treatment by laparoscopy. After 5 days, more ewes were ovulating in response to full ram contact than in any other treatment (P less than 0.05) and more ewes in fenceline contact with rams or with rams plus ewes were ovulating than in the isolated control treatment (P less than 0.01). In Exp. 3, 6 groups of about 40 anovulatory ewes were exposed to face masks with and without rams' wool and/or various degrees of contact with rams for 5 days. More ewes were ovulating after 5 days in the group in full physical contact with rams than in any other group (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)