There is a substantial lack of knowledge in the Hungarian scientific literature on the possibilities of embryo transfer in horses. In these two articles the authors try to highlight this area of research both with a thorough review of the literature and with a report of the first successful embryo transfer in mares in Hungary. The review begins with a historical introduction of the most important steps in equine embryo transfer then it is followed by a systematic description of the technique. Emphasis should be put on the proper selection of both the donor and recipient mares. Recipients should be of 3 to 10 years of age with moderate condition and good fertility. The success of the transfer is depend on the synchrony between the donors and recipients. Recipient should ovulate either 1 day before or 3 days after the donors. In case of limited number of recipients the synchronisation can be carried out using progestins, PGF2α and HCG. The flushings can be done on day 6-8 after ovulation using the so called gravitation technique with 1-3 litres of DPBS containing 1% fetal calf serum. The average recovery rate is approximately 60-80% but major differences may occur depending on the reproductive background of the donors, the semen quality and the time of flushings (day 6-day 8). Embryos are recovered either as morula (day 6, 150-200 μm) or blastocyst (day 7-8, early, expanding, 400-800 μm) and are morphologically scored on the 1 to 5 scale (1 excellent, 5 degenerated). Transfers should be performed as soon as possible after recovery either surgically or non surgically. In case of the surgical technique midline or flank approach can be used resulting in higher pregnancy rate than the non surgical way. The difference between the two technique maybe the result of local inflammation and PGF2α-release owing to cervical dilation during the manipulation. There is also intensive research on different methods to improve the efficiency of equine embryo transfer. Crude equine gonadotrophin can be used for superovulation which result in elevated ovulation rate but has a negative effect on the recovery rate. The freezing of equine embryos can also be done successfully but large scale practical application has not been achieved yet.
|Translated title of the contribution||Possibilities and problems associated with embryo transfer in horses. 1. Review|
|Number of pages||6|
|Journal||Magyar Allatorvosok Lapja|
|Publication status||Published - Dec 1 1996|
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