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 HighWire Citing Articles via Google Scholar Google Scholar Articles by Diskin, M. G. Articles by Niswender, G. D. Search for Related Content PubMed PubMed Citation Articles by Diskin, M. G. Articles by Niswender, G. D.

Effect of Progesterone Supplementation on Pregnancy and Embryo Survival in Ewes¹

Colorado State University^,4, Fort Collins 80523

Abstract

Two hundred eighteen ewes were used in experiments 1) to develop a progesterone supplementation regimen capable of sustaining serum concentrations of progesterone at about 2.0 ng/ml for a period of 50 d (Exp. 1) and 2) to determine the effects of progesterone supplementation (d 6 to 50 after mating) on pregnancy and embryo survival rates in mated ewes (Exp. 2). In ovariectomized ewes in Exp. 1, s.c. administration of four cylindrical (9.5 x 60 mm) silastic implants, containing 20% (1.1 g) progesterone by weight, sustained mean serum concentrations of progesterone of 1.9 ± .07 ng/ml compared with 1.03 ± .05 ng/ml in ewes bearing two implants. In Exp. 2 each ewe (n = 159) was mated to two fertile rams at a spontaneous estrus (d 0) during mid-breeding season. Mean ovulation rate, determined on a subgroup of 46 ewes, was 1.45 ± .05. On d 6, ewes were assigned randomly to control (two implants containing no progesterone) or progesterone-treated (four implants similar to those used in Exp. 1) groups. From d 7 to 50 after mating, progesterone concentrations in serum were greater (P < .001) in progesterone-treated (3.50 ± .06) than in control (2.65 ± .05) ewes. Pregnancy rates (86% and 83%) and calculated embryo survival rates (77% and 78%) were similar (P > .05) for the the control and progesterone-treated groups, respectively. It was concluded that when fertility is high (>75% embryo survival), luteal insufficiency is not the predominant cause of embryo mortality so embryo survival rate is unlikely to be increased by exogenous progesterone.

¹ This research was supported by the Colorado Exp. Sta.

² Supported by The Agric. & Food Dev. Authority. Ireland. Present address: The Agric. & Food Dev. Authority, Belclare, Tuara, Co. Galway, Ireland.

³ To whom correspondence and reprint requests should be addressed.

⁴ Anim. Reprod. Lab., Dept. of Physiol.

This article has been cited by other articles:

				A. B. Dixon, M. Knights, J. L. Winkler, D. J. Marsh, J. L. Pate, M. E. Wilson, R. A. Dailey, G. Seidel, and E. K. Inskeep Patterns of late embryonic and fetal mortality and association with several factors in sheep J Anim Sci, May 1, 2007; 85(5): 1274 - 1284. [Abstract] [Full Text] [PDF]