Comparison of the effects of eFSH and deslorelin treatment regimes on ovarian stimulation and embryo production of donor mares in early vernal transition.

This research compared the impacts of two hormone treatments, eFSH and deslorelin, on ovulation and embryo production in mares during early spring transition, finding both treatments to be equally effective in inducing ovulation, but the eFSH treatment resulted in more ovulations and recovered embryos.

Objective of the Study

This research aimed to assess and compare the efficacy of two different hormone treatment regimes (eFSH and deslorelin) in terms of ovarian stimulation and embryo production in mares during early vernal transition, a period typically noted as troublesome for managing broodmare reproduction.

Research Methodology

• The experiment began on January 30th with mares that were kept under ambient light conditions.
• Veterinarians carried out transrectal ultrasonography on each of the mares to identify if a follicle sized 25 mm or larger was present.
• If such a follicle was detected, the mare was then assigned to one of two treatment groups in a sequential alternating manner.
• In the eFSH group, each of the 18 mares was treated twice daily with eFSH (at a dosage of 12.5mg administered intramuscularly) until a follicle sized 35 mm or larger was detected; they were then given hCG 36 hours later.
• In the deslorelin group, the 18 mares were treated twice daily with deslorelin (at a dosage of 63 micrograms administered intramuscularly) until a follicle sized 35 mm or larger was identified and they were then given hCG.
• During estrus, the mares were artificially inseminated with fresh semen.
• Eight days after ovulation, attempts were made to retrieve the embryo(s).

Research Results

• Both eFSH and deslorelin treatment regimes successfully induced ovulation in 78% of the mares (14 out of 18) in their respective groups.
• The average interval from starting the treatment to ovulation was slightly longer with eFSH (8.2 days) than with deslorelin (7.2 days).
• Furthermore, the eFSH group showed significantly higher numbers of ovulations (3.4 on average), compared to that of the deslorelin group (1.1 on average).
• The eFSH treatment also resulted in more embryos retrieved per recovery attempt, with an average of 2.6 compared to the deslorelin group’s average of 0.4.

Conclusions of the Study

The researchers concluded that both eFSH and deslorelin could be effectively used for inducing ovulation in mares during early vernal transition, within a predictable timeframe. However, the eFSH treatment resulted in more ovulations and embryos per mare, indicating a potential higher reproductive yield, thus making an effective choice for the maximization of embryo production in horses.