Abstract

The aims of this study were to compare ovarian and oestrous activity in ewes teased over a range of dates in late anoestrus by either rams or bucks. Entire Dorset rams or feral bucks (male goats) were joined with anovular Romney ewes on either January 20, 27; February 3, 10 or 17 in a 2 x 5 factorial design (N=350). Ovulations were determined 4 d later and first oestrus up to 6 weeks later. On day 8, ovulations were determined in ewes anovular on day 4 to buck teasings. Spontaneous ovulations first occurred in mid February. Rams were more effective than bucks at inducing ovulations. Furthermore, rams induced ovulations in ewes that failed to respond to bucks. Date of teasing had no effect on the pattern of first matings in ovulating ewes. Ewes stimulated to ovulate by rams tended to display oestrus earlier than ewes stimulated by bucks. These results demonstrate that rams and bucks will initiate early ovulation and oestrus in ewes, but rams are superior teasers to bucks.

PR, Journeaux, AF McRae, and WJ Parker

Proceedings of the New Zealand Society of Animal Production, Volume 47, , 119-122, 1987