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 Smith, R. D. Articles by Hansel, W. Search for Related Content PubMed PubMed Citation Articles by Smith, R. D. Articles by Hansel, W.

Insemination of Holstein Heifers at a Preset Time after Estrous Cycle Synchronization Using Progesterone and Prostaglandin^1,2,

Cornell University, Ithaca, NY 14853

Abstract

Two experiments were conducted to study estrous cycle control regimens that combine progesterone administration via an intravaginal device (PRID) with a single injection of prostaglandin F₂ (PG). In Exp. I, 242 Holstein heifers were assigned randomly to one of three treatment groups at 14 to 18 mo of age. Treatments were: 1) control, 2) PRID-6 + PG-6 (PRID in place for 6 d plus PG on the day of PRID removal) and 3) PRID-7 + PG-6 (PRID in place for 7 d plus PG on the day before PRID removal). Heifers were observed for estrous activity and were inseminated at 8 to 20 h after estrus was detected. Estrus and ovulation were effectively synchronized after both PRID + PG treatments. Ninety-nine percent of the heifers in each group were in estrus within 168 h after PG injection. However, the interval from PG administration to the onset of estrus was longer after PRID-7 + PG-6 (75 ± 2 h) than after PRID-6 + PG-6 (66 ± 2 h). A lower variance in the interval from PG treatment to estrus was observed after PRID-7 + PG-6, suggesting that the 24 h delay in PRID withdrawal improved the synchrony of the onset of estrus. Pregnancy rates (72 to 82%) did not vary across treatment groups. Two-hundred seventy-four heifers were assigned to Exp. II. Treatments were 1) control, 2) 2 X PG (two injections of PG at an 11 d interval) and 3) PRID-7 + PG-6. Animals were observed for estrus, but inseminations were performed at a single preset time without regard to estrous activity (80 and 84 h after PG administration in 2 X PG and PRID-7 + PG-6 groups, respectively). Fewer heifers in the 2 x PG group (84%) were observed in estrus within 120 h after treatment and the interval from PG to estrus was shorter (61 ± 2 h) than in the PRID-7 + PG-6 group (94% and 73 ± 1 h). Pregnancy rate in 2 x PG-treated heifers (52%) was lower than in controls bred at a naturally occurring estrus (73%) and PRID-7 + PG-treated heifers (66%). Lower conception rates in 2 X PG-treated heifers were due to 1) poorer synchrony of estrus, 2) failure of a significant number (16%) of the heifers to respond to the second PG injection and(or) 3) improperly timed inseminations. The PRID-7 + PG-6 treatment provides the necessary precision in estrus and ovulation control to allow successful insemination at a single preset time.

¹ Research reported in this manuscript was completed as part of Cornell University's contribution to the NE-72 regional project 'Control of Reproduction in the Bovine Female' and was conducted under Federal Drug Administration INAD #975.

² Progesterone releasing intravaginal devices (PRID) were generously donated by Abbott Laboratories, Chicago, IL and prostaglandin F₂ (PG) by the Upjohn Co., Kalamazoo, MI.

³ Dept. of Anim. Sci., Cornell Univ.

⁴ Present address: Dept. of Anim. Sci., Virginia Polytechnic Institute and State Univ., Blacksburg, VA 24061.

⁵ Present address: Diagnostic Endocrinol. Lab., College of Vet. Med., Cornell Univ.

⁶ Present address: Dept. of Physiol., College of Vet. Med., Cornell Univ.

This article has been cited by other articles:

				J. S. Stevenson Progesterone, Follicular, and Estrual Responses to Progesterone-Based Estrus and Ovulation Synchronization Protocols at Five Stages of the Estrous Cycle J Dairy Sci, December 1, 2008; 91(12): 4640 - 4650. [Abstract] [Full Text] [PDF]

				D. J. Schafer, J. F. Bader, J. P. Meyer, J. K. Haden, M. R. Ellersieck, M. C. Lucy, M. F. Smith, and D. J. Patterson Comparison of progestin-based protocols to synchronize estrus and ovulation before fixed-time artificial insemination in postpartum beef cows J Anim Sci, August 1, 2007; 85(8): 1940 - 1945. [Abstract] [Full Text] [PDF]

				A. M. Richardson, B. A. Hensley, T. J. Marple, S. K. Johnson, and J. S. Stevenson Characteristics of estrus before and after first insemination and fertility of heifers after synchronized estrus using GnRH, PGF2{alpha}, and progesterone J Anim Sci, November 1, 2002; 80(11): 2792 - 2800. [Abstract] [Full Text] [PDF]