Reproductive characteristics of spontaneous single and double ovulating mares and superovulated mares.

The study investigates the reproductive traits of mares ovulating either singly or doubly, and those induced to superovulate, finding that both natural and induced multi-ovulation leads to a higher rate of viable embryos, improving the efficiency of horse embryo transfer.

Research Finding Overview

• The study found that the recovery of embryos from single-ovulating mares 7 days after ovulation was 53%, whereas it was 106% for double-ovulating mares.
• The pregnancy rates 50 days after the surgical transfer of the embryos were also higher for the latter, indicating that natural double ovulation leads to a more successful embryo recovery and pregnancy.
• The research also found there was no significant difference in LH concentrations during the periovulatory period in cycles involving single or double ovulations.

Superovulation Results

• Administering horse pituitary extract for a duration of 5.5 days induced more than two ovulations (an average of 3.8) in the majority of the mares.
• Embryo recovery per donor increased to 2.0 in superovulated mares, compared to 0.65 in controls.
• The pregnancy rates for embryos collected from superovulated mares were identical to those for untreated controls, supporting that superovulation doesn’t harm the chances of subsequent successful pregnancy.
• A noteworthy find was that superovulated donors that provided multiple embryos had an overall pregnancy rate of 120%.

Significance of the Study

• The study demonstrates that the viability of embryos from both spontaneous and induced multi-ovulating mares equals that of embryos from single-ovulating mares.
• This finding is significant as it suggests that collecting and transferring embryos from mares that have experienced multiple ovulations can improve the efficiency of horse embryo transfer.
• The research could potentially have widespread utility in equine breeding strategies and practices, offering a promising prospect for enhancing successful pregnancies in mares.