Abstract

In anoestrous ewes that have been primed with progestagens, the introduction of oestrous ewes together with the teaser rams at progestagen withdrawal increased the percentage of ewes exhibiting oestrus over the subsequent 7 days (19.% teaser rams only v 24.4% teaser rams + oestrous ewes; Experiment 1) and the percentage of ewes ovulating in the subsequent 5 days (7.7% teaser rams only v 21.6% teaser rams + oestrous ewes; Experiment 2). The introduction of oestrous ewes without teaser rams in Experiment 2 failed to stimulate anoestrous ewes to ovulate. When rams were placed with oestrous ewes for 2 days before they alone were introduced to anoestrous ewes, the percentage of ewes ovulating was similar to when rams plus oestrous ewes were present together (38.1% stimulated teaser rams v 35.0% teaser rams + oestrous ewes; Experiment 3). Both of these treatments resulted in more ewes ovulating than in the isolated ewes (0.0%) with the response to unstimulated teaser rams (19.5%) and to oestrous ewes alone (9.5% being intermediate.

ATG, McArthur

Proceedings of the New Zealand Society of Animal Production, Volume 45, , 39-42, 1985