HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Langford, G. A. Search for Related Content PubMed PubMed Citation Articles by Langford, G. A.

Influence of PMSG and Time of Aritificial Insemination on Fertility of Progestogen-Treated Sheep in Confinement^1,2,

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

Abstract

The need for pregnant mares' serum gonadotropin (PMSG) in breeding confined sheep by artificial insemination (AI) at progestogen-synchronized estrus was assessed in 152 adult crossbred ewes brought into season by a controlled light regimen. One-half of the ewes received 500 IU PMSG after intravaginal progestogen treatment; all ewes were inseminated either 54, 57 or 60 h after sponge removal or at 54 and again at 60 h. Based on progesterone determinations 18 d after AI, conception rates with single insemination 54, 57 or 60 h and double insemination at 54 and 60 h were 76, 72, 47 and 72%, respectively, among ewes receiving PMSG, compared to 17, 22, 47 and 43%, respectively, among ewes not given PMSG (P<.01). Lambing rates were higher (P<.01) with PMSG (67, 67, 37 and 61%) than without PMSG (11, 11, 26 and 33%). While there was only a small increase (.06>P>.05) in litter size with PMSG, fecundity decreased (P<.01) from 1.4 to .3 when PMSG was not used. These data indicate that, even with controlled lighting to induce estrous activity, additional stimulation of ovulation by PMSG at progestogen-synchronized estrus is necessary for normal fertility when confined sheep are bred by AI.

¹ Contribution No. 984, Animal Research Center.

² The author is pleased to acknowledge Drs. L. Ainsworth, A. J. Hackett and D. P. Heaney for assistance in estrus synchronization and artificial insemination; Drs. G. J. Marcus and T. R. Batra for helpful suggestions in preparation of the manuscript and in statistical analyses; Dr. P. S. Fiser for suggestions on figure 1; P. Panich for technical assistance, and J. Arcand, J. F. Hunter and D. Ostapyk for care of the sheep.