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Equine veterinary journal2023; 56(1); 131-136; doi: 10.1111/evj.13936

Delayed embryonic development or a long sperm survival in two mares-A registration conundrum.

Abstract: Genetic testing is required for the registration of foals of most equine breeds. Objective: To describe two clinical cases of marked delayed embryonic development or delayed fertilisation in pregnancies generated by embryo transfer. Methods: Case report. Methods: Donor mares were inseminated with semen from one stallion during one oestrous cycle and semen from a different stallion on the subsequent oestrous cycle. Embryo(s) were collected 8 days after ovulation during the second oestrous cycle and transferred into synchronised recipient mares. Genetic testing was performed to determine parentage of the two foals. Results: For both foals, DNA parentage testing excluded the second stallion as the genetic sire and confirmed that the first stallion, whose semen was inseminated on the previous oestrous cycle, was the actual genetic sire. Conclusions: Rare event in horses; two clinical cases are described. Conclusions: It is hypothesised that either marked delayed embryonic development or extended sperm survival occurred in the donor mares. Without genetic testing, parentage assignment based solely on breeding records would have been incorrect.
© 2023 The Authors. Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.
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Publication Date: 2023-03-20 PubMed ID: 36917554DOI: 10.1111/evj.13936Google Scholar: Lookup
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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.

This research focuses on two instances of significant delayed embryonic development or extended sperm survival in horse pregnancies achieved through embryo transfer. Through genetic testing, it was discovered that the sire was not from the most recent insemination but from a previous one, leading to questions about commonly held beliefs on equine breeding and the necessity of genetic testing for accurate lineage.

Research Methods

  • This study uses a case report method to delve into two unique clinical cases of pronounced delayed embryonic development or late fertilisation in pregnancies that were realised through embryo transfer.
  • The donor mares were inseminated with semen from one stallion during one heat cycle, and then with semen from a different stallion in the following heat cycle.
  • Embryos were then collected 8 days post ovulation during the second heat cycle and then transferred to synchronised recipient mares.
  • A genetic test was performed to identify the parentage of the two foals born through this process.

Research Findings

  • The DNA parentage test excluded the stallion from the second insemination as the genetic sire and established that the stallion from the first insemination was indeed the genetic sire of both foals.
  • This surprising result leads the researchers to believe that either marked delayed embryonic development or extended sperm survival occurred in the donor mares.
  • That’s because, traditionally, it has been thought that the sire would be the stallion from the most recent insemination.

Research Implications and Conclusions

  • This is considered a rare event in horses, and the research paper describes these two unusual cases in detail.
  • These findings guarantee the necessity of genetic testing in equine offspring as, without it, parentage determination based entirely on breeding records might have been incorrect.
  • This study therefore challenges pre-existing assumptions regarding equine breeding and underlines the importance of applying modern genetic testing techniques within equine registration processes.

Cite This Article

APA
McCue PM, Matthews PM, Prell MJ, Bellone RR, Allen H. (2023). Delayed embryonic development or a long sperm survival in two mares-A registration conundrum. Equine Vet J, 56(1), 131-136. https://doi.org/10.1111/evj.13936

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English
Volume: 56
Issue: 1
Pages: 131-136

Researcher Affiliations

McCue, Patrick M
  • Equine Reproduction Laboratory, Colorado State University, Fort Collins, Colorado, USA.
Matthews, Philip M
  • Peterson Smith Advanced Fertility Center, Peterson & Smith Equine Hospital, Ocala, Florida, USA.
Prell, Melissa J
  • Peterson Smith Advanced Fertility Center, Peterson & Smith Equine Hospital, Ocala, Florida, USA.
Bellone, Rebecca R
  • Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California, Davis, California, USA.
  • Department of Population Health and Reproduction, School of Veterinary Medicine University of California, Davis, California, USA.
Allen, Heather
  • Bureau Veritas Laboratories, Guelph, Ontario, Canada.

MeSH Terms

  • Pregnancy
  • Horses
  • Animals
  • Male
  • Female
  • Insemination, Artificial / veterinary
  • Semen
  • Spermatozoa
  • Semen Preservation / veterinary
  • Embryonic Development

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Citations

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