Use of oocyte transfer in a commercial breeding program for mares with reproductive abnormalities.

This study reveals a successful method for inducing pregnancy in subfertile mares with reproductive abnormalities referred to as oocyte transfer. The method was applied over two breeding seasons and proved effective, with 20 pregnancies achieved, which led to the birth of 14 live foals.

Background

• The research investigated the use of oocyte transfer in mares with reproductive issues that hindered successful embryo collection and survival. These mares often struggle to conceive or maintain pregnancies due to lesions in their reproductive tracts.
• Oocyte transfer was presented as a potential solution to this problem, aiming to boost the mares’ chances of successfully carrying a pregnancy to term.

Methodology

• The researchers used a technique which involves stimulating follicular and oocyte maturation in the mares. This was done with either human chorionic gonadotropin or an implant containing a gonadotropin-releasing hormone analog.
• The matured oocytes were then collected through transvaginal ultrasound-guided follicular aspiration, which is a minimally invasive procedure.
• After collecting the oocytes, cumulus oocyte complexes were evaluated for cumulus expansion and signs of atresia. Immature oocytes were cultivated in vitro to stimulate maturation.
• The final step in the method involved exposing the recipient’s ovary and uterine tube (oviduct) via a flank laparotomy with the horse standing. The mature oocyte was then carefully placed within the oviduct.

Results

• Oocyte transfer was attempted in 38 mares aged between 9 and 30 years old over two consecutive breeding seasons.
• Each mare in the study had a history of reproductive failure while in breeding and embryo transfer programs.
• The result of the research was favorable, with 20 successful pregnancies achieved from the oocyte transfers. Of these pregnancies, 14 led to the birth of live foals.

Conclusion

• The study concluded that oocyte transfer can be an advantageous method for inducing pregnancy in mares with reproductive tract abnormalities.
• These findings suggest that the utilization of this method can enhance the success rates of pregnancies in subfertile mares in commercial settings, thus potentially improving the overall productivity and profitability of the equine industry.