Time of ovulation in Merino ewes superovulated with PMSG and FSH-P [sheep]

Ryan, J.P.; Hunton, J.R.; Maxwell, W.M.C.

Time of ovulation in Merino ewes superovulated with PMSG and FSH-P [sheep]

1992

Ryan, J.P. | Hunton, J.R. | Maxwell, W.M.C. (Western Australian Dept. of Agriculture, Katanning. Animal Breeding and Research Inst.)

In an experiment on 182 ewes superovulated with a combination of 400 I.U. PMSG and 12 mg FSH-P, time of ovulation was influenced by both season and the administration of GnRH. Two peaks of ovulation were observed in spring, the first between 24 and 30 h after progestagen sponge removal, and the second commencing 42 h after sponge removal. In autumn, there was 1 peak of ovulation between 42 and 54 h after sponge removal. Treatment with GnRH advanced the time of ovulation in autumn, but had no apparent effect in spring. In contrast to the effect of GnRH, time of ovulation for ewes treated in the autumn was delayed by supplementary feeding with lupins.

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