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Reproductive characteristics of spontaneous single and double ovulating mares and superovulated mares.

Abstract: For embryos collected from mares 7 days after ovulation, embryo recovery for single-ovulating mares was 53% compared to 106% for double-ovulating mares. Pregnancy rates 50 days after surgical transfer were 68 and 129%, respectively. Concentrations of LH were similar during the periovulatory period for cycles which included single or double ovulations. Horse pituitary extract given for 5.5 days resulted in greater than or equal to 2 ovulations (mean 3.8) in 26 of 28 mares and 2.0 embryos were recovered per donor compared to 0.65 for controls. Non-surgical pregnancy rates for embryos collected from superovulated mares 6 and 8 days after ovulation (18 of 46; 39%) were identical to those obtained for untreated controls (12 of 31; 39%). The overall pregnancy rate for superovulated donors, which provided 2-4 embryos, was 120%. Since the viability of multiple embryos collected from spontaneous and induced multiple-ovulating mares was equal to that of embryos from single-ovulating mares, collection and transfer of embryos from these mares will increase the efficiency of horse embryo transfer.
Publication Date: 1987-01-01 PubMed ID: 3479594
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  • Journal Article
  • Research Support
  • Non-U.S. Gov't

Summary

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The study investigates the reproductive traits of mares ovulating either singly or doubly, and those induced to superovulate, finding that both natural and induced multi-ovulation leads to a higher rate of viable embryos, improving the efficiency of horse embryo transfer.

Research Finding Overview

  • The study found that the recovery of embryos from single-ovulating mares 7 days after ovulation was 53%, whereas it was 106% for double-ovulating mares.
  • The pregnancy rates 50 days after the surgical transfer of the embryos were also higher for the latter, indicating that natural double ovulation leads to a more successful embryo recovery and pregnancy.
  • The research also found there was no significant difference in LH concentrations during the periovulatory period in cycles involving single or double ovulations.

Superovulation Results

  • Administering horse pituitary extract for a duration of 5.5 days induced more than two ovulations (an average of 3.8) in the majority of the mares.
  • Embryo recovery per donor increased to 2.0 in superovulated mares, compared to 0.65 in controls.
  • The pregnancy rates for embryos collected from superovulated mares were identical to those for untreated controls, supporting that superovulation doesn’t harm the chances of subsequent successful pregnancy.
  • A noteworthy find was that superovulated donors that provided multiple embryos had an overall pregnancy rate of 120%.

Significance of the Study

  • The study demonstrates that the viability of embryos from both spontaneous and induced multi-ovulating mares equals that of embryos from single-ovulating mares.
  • This finding is significant as it suggests that collecting and transferring embryos from mares that have experienced multiple ovulations can improve the efficiency of horse embryo transfer.
  • The research could potentially have widespread utility in equine breeding strategies and practices, offering a promising prospect for enhancing successful pregnancies in mares.

Cite This Article

APA
Squires EL, McKinnon AO, Carnevale EM, Morris R, Nett TM. (1987). Reproductive characteristics of spontaneous single and double ovulating mares and superovulated mares. J Reprod Fertil Suppl, 35, 399-403.

Publication

ISSN: 0449-3087
NlmUniqueID: 0225652
Country: England
Language: English
Volume: 35
Pages: 399-403

Researcher Affiliations

Squires, E L
  • Animal Reproduction Laboratory, Colorado State University, Fort Collins 80523.
McKinnon, A O
    Carnevale, E M
      Morris, R
        Nett, T M

          MeSH Terms

          • Animals
          • Embryo Transfer / veterinary
          • Female
          • Horses / physiology
          • Ovulation
          • Pregnancy
          • Pregnancy, Animal / physiology
          • Superovulation

          Citations

          This article has been cited 2 times.
          1. Sirois J, Betteridge KJ, Brault A. Transcervical embryo transfer in horses: an application in an equestrian teaching center. Can Vet J 1987 Dec;28(12):750-3.
            pubmed: 17422935
          2. Panzani D, Vannozzi I, Sgorbini M, Corazza M, Rota A, Pacini M. Embryo recovery rate in a mare affected by Cushing's syndrome. Vet Res Commun 2003 Sep;27 Suppl 1:619-21.