J. Anim Sci.
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J. Anim Sci. 1982. 54:12-17.
© 1982 American Society of Animal Science
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Reproductive Response of Progestogen-Treated Sheep in Confinement to a Single and Double Insemination1,2

G. A. Langford, L. Ainsworth and M. S. Wolynetz3

Animal Research Centre, Agriculture Canada Ottawa, Ontario K1A 0C6

Abstract

The reproductive responses to one and two inseminations of fresh extended semen were compared in crossbred sheep housed in confinement. In three trials, ewes in progestogen-induced estrus were inseminated 54 to 56 h after sponge removal. Half the ewes received a second insemination 4 or 5 h later. Resultant fertility, litter size and embryonic mortality indicated no advantage to a double insemination. Conception rates to one and two inseminations according to d 18 plasma progesterone levels were 66 and 63%, 85 and 86% and 74 and 80% in trials 1, 2 and 3, respectively. Corresponding lambing rates were 55 and 56%, 73 and 69% and 67 and 76%. Mean litter sizes were 2.1 and 2.5, while embryonic mortality after the first 2 wk of pregnancy was estimated at 13% for both groups. Single inseminations therefore simplify artificial insemination and double the number of ewes that can be inseminated/ejaculate.

Key Words: Single Insemination • Fresh Semen • Fertility • Sheep

Footnotes

1 Contribution No. 968 Animal Research Centre; Contribution No. 1-250 Engineering and Statistical Research Institute.

2 We would like to thank Dr. A. J. Hackett and Dr. D. P. Heaney for assistance in sponging and inseminations; J. Arcand, J. F. Hunter and D. Ostapyk for care of the sheep, and P. Panich and B. Graham for technical assistance.

3 Statistical Research Section, Engineering and Statistical Research Institute, Agriculture Canada, Ottawa, Ontario K1A 0C6.






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Copyright © 1982 by the American Society of Animal Science.