Post-mating progesterone supplementation in ewes and hoggets
W.H. McMillan
Whatawhata Hill Country Research Centre, Ministry of Agriculture
and Fisheries, Hamilton
Proceedings of the New Zealand Society of Animal Production.
1987, 47: 151-154
Treatment with progesterone impregnated controlled internal
drug releasers (CIDR) in early pregnancy can increase ewe reproductive
performance. Return mating patterns, pregnancy rates and multiple
pregnancies were evaluated in supplemented ewes and hoggets.
Supplementation was over the 5 d from day 7 to 9 until day 12 to 14
post-mating. Supplementation had no effect on the pattern and incidence
of return matings in ewes. In contrast, supplemented hoggets tended to
return later with less returning (18% v 35%). Supplementation had no
effect on ewe pregnancy rate although more supplemented hoggets lambed
to first service (79% v 56%, P<0.05). Supplementation increased
multiple pregnancies resulting in 23% more foetuses in ewes and 40% more
in hoggets. The progesterone supplemented sheep may be a useful
experimental model for studies in reproductive wastage.
Keywords: NZSAPAB;
Post-mating progesterone supplementation; mating; pregnancy;
embryo mortality
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Last Updated 03-05-1997
