The effect of priming and duration of oestradiol benzoate treatment before progesterone administration on embryo development and survival in anestrous recipient mares.

The study investigated how different hormonal treatments influence the survival of embryos in mares that are not in the estrus cycle. The focus of the experiment was the effect of three differing hormonal treatments on the survival rate of the embryos two days post-transfer.

Research Methodology

• The experimental approach involved the division of recipient mares into three groups, each given a different hormonal treatment to prepare the mare for receiving the embryo.
• The three treatments included progesterone-only treatment (NE) four days before embryo transfer; a single administration of 2.5 mg of oestradiol benzoate (SE) two days prior to progesterone treatment; and a treatment involving 8 mg of oestradiol split over five consecutive days (LE) ending three days before progesterone treatment.

Findings

• Two days post-transfer, the probability of recovering a viable embryo was distinctly different among the groups: 46.1% for the NE group, 62.5% for the SE group, and an impressive 85.7% for the LE group.
• Although these results lean significantly towards the latter treatment, the differences were not statistically significant with a p-value of .09 (a p-value of less than .05 is generally accepted as statistically significant in research).

Conclusions

• The study concluded that presence and duration of oestradiol treatment before progesterone administration have the tendency to affect the survival rate of the embryos in anestrous recipient mares 2 days post-transfer.
• One important finding from the study is that the surviving embryos among all three groups did not show any differences in size and morphology which indicates that the differing treatments did not impact the health or development of the embryos.
• Even though further research might be needed to investigate the impact of differing hormonal treatments on embryo survival rate statistically, these findings show promise for improving the chances of survival for embryos transferred to anestrous mares.