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Home / Equine Research Bank / Theriogenology / Factors affecting pregnancy rates and early embryonic death ...
Theriogenology2000; 54(6); 965-979; doi: 10.1016/S0093-691X(00)00405-2

Factors affecting pregnancy rates and early embryonic death after equine embryo transfer.

Abstract: In the present study, 638 embryo transfers conducted over 3 yr were retrospectively examined to determine which factors (recipient, embryo and transfer) significantly influenced pregnancy and embryo loss rates and to determine how rates could be improved. On Day 7 or 8 after ovulation, embryos (fresh or cooled/transported) were transferred by surgical or nonsurgical techniques into recipients ovulating from 5 to 9 d before transfer. At 12 and 50 d of gestation (Day 0 = day of ovulation), pregnancy rates were 65.7% (419 of 638) and 55.5% (354 of 638). Pregnancy rates on Day 50 were significantly higher for recipients that had excellent to good uterine tone or were graded as "acceptable" during a pretransfer examination, usually performed 5 d after ovulation, versus recipients that had fair to poor uterine tone or were graded "marginally acceptable." Embryonic factors that significantly affected pregnancy rates were morphology grade, diameter and stage of development. The incidence of early embryonic death was 15.5% (65 of 419) from Days 12 to 50. Embryo loss rates were significantly higher in recipients used 7 or 9 d vs 5 or 6 d after ovulation. Embryos with minor morphological changes (Grade 2) resulted in more (P<0.05) embryo death than embryos with no morphological abnormalities (Grade 1). Between Days 12 and 50, the highest incidence of embryo death occurred during the interval from Days 17 to 25 of gestation. Embryonic vesicles that were imaged with ultrasound during the first pregnancy exam (5 d after transfer) resulted in significantly fewer embryonic deaths than vesicles not imaged until subsequent exams. In the present study, embryo morphology was predictive of the potential for an embryo to result in a viable pregnancy. Delayed development of the embryo upon collection from the donor or delayed development of the embryonic vesicle within the recipient's uterus was associated with a higher incidence of pregnancy failure. Recipient selection (age, day after ovulation, quality on Day 5) significantly affected pregnancy and embryo loss rates.
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Publication Date: 2000-11-30 PubMed ID: 11097048DOI: 10.1016/S0093-691X(00)00405-2Google Scholar: Lookup
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  • Journal Article
  • Research Support
  • Non-U.S. Gov't

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research article examines the influential factors upon pregnancy rates and early embryonic death in equine embryo transfers. The study conducted a detailed analysis of 638 embryo transfers over a 3-year period and discovered that recipient, embryo, and transfer attributes noticeably impact pregnancy and embryo loss outcomes.

Methodology

  • The research involved retrospective analysis of 638 embryo transfers completed within 3 years.
  • Embryo transfers were administered on Day 7 or 8 after ovulation.
  • Both fresh and cooled/transported embryos were transferred using surgical or non-surgical techniques into recipients ovulating from 5 to 9 days before the transfer.
  • Pregnancy rates were measured at Days 12 and 50 of gestation, with Day 0 slated as the day of ovulation.

Findings

  • The pregnancy rates on Day 50 were notably higher for recipients with good to excellent uterine tone or those categorized as “acceptable” during the pre-transfer examination compared to those with fair to poor uterine tone or defined as “marginally acceptable”.
  • Embryonic factors influencing pregnancy rates included morphology grade, diameter, and stage of development. Likewise, embryos with minor morphological changes demonstrated higher embryo death rates than embryos with no morphological abnormalities.
  • The highest occurrence of embryo death was recorded from Days 17 to 25 of gestation.
  • Embryonic vesicles examined through ultrasound during the first pregnancy test resulted in fewer embryonic deaths compared to vesicles not analyzed till subsequent checks.

Conclusion

  • The study identified that the embryo’s morphology indicates the viability of the pregnancy.
  • Delayed development of the embryo post collection from the donor or belated progression of the embryonic vesicle within the recipient’s uterus was linked to a higher rate of pregnancy failure.
  • The research also established that recipient selection, factoring in age and day post ovulation and quality on Day 5, significantly impacts pregnancy and rates of embryo loss.

Cite This Article

APA
Carnevale EM, Ramirez RJ, Squires EL, Alvarenga MA, Vanderwall DK, McCue PM. (2000). Factors affecting pregnancy rates and early embryonic death after equine embryo transfer. Theriogenology, 54(6), 965-979. https://doi.org/10.1016/S0093-691X(00)00405-2

Publication

Theriogenology
ISSN: 0093-691X
NlmUniqueID: 0421510
Country: United States
Language: English
Volume: 54
Issue: 6
Pages: 965-979

Researcher Affiliations

Carnevale, E M
  • Animal Reproduction and Biotechnology Laboratory, Colorado State University, Fort Collins 80523, USA.
Ramirez, R J
    Squires, E L
      Alvarenga, M A
        Vanderwall, D K
          McCue, P M

            MeSH Terms

            • Acepromazine / administration & dosage
            • Animals
            • Dopamine Antagonists / administration & dosage
            • Embryo Loss / veterinary
            • Embryo Transfer / methods
            • Embryo Transfer / veterinary
            • Female
            • Horses / embryology
            • Horses / physiology
            • Laparotomy / veterinary
            • Pregnancy
            • Pregnancy Rate
            • Regression Analysis
            • Retrospective Studies

            Citations

            This article has been cited 14 times.
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