Delayed embryonic development or a long sperm survival in two mares-A registration conundrum.
Equine Vet J 2024;
56:131-136. [PMID:
36917554 DOI:
10.1111/evj.13936]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 03/08/2023] [Indexed: 03/16/2023]
Abstract
BACKGROUND
Genetic testing is required for the registration of foals of most equine breeds.
OBJECTIVES
To describe two clinical cases of marked delayed embryonic development or delayed fertilisation in pregnancies generated by embryo transfer.
STUDY DESIGN
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.
MAIN LIMITATIONS
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.
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