Are rams necessary for the stimulation of anoestrous ewes with
oestrous ewes?
T.W. Knight
Whatawhata Hill Country Research Station, Ministry of Agriculture
and Fisheries, Hamilton
Proceedings of the New Zealand Society of Animal Production.
1985, 45: 49-50
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.
Keywords: NZSAPAB;
Rams; anoestrous ewes; oestrous ewes; ram effect; ovulation;
social stimulation
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Last Updated 03-05-1997
