Establishment and maintenance of pregnancy after embryo transfer in ovariectomized mares treated with progesterone.

This research studied the use of progesterone to induce and maintain pregnancy in mares (female horses) that had their ovaries removed. Through the transfer of embryos and continuous progesterone treatment, it was successful in achieving pregnancy and normal childbirth in three of the four mares studied.

Objective of the Research

• The research sought to determine if continuous progesterone treatment can establish and maintain pregnancy in mares that have had their ovaries removed. This was performed through the process of embryo transfer.

Methodology

• Four mares without ovaries were used in the experiment. These mares were treated with 300 mg of progesterone daily, commencing five days before an embryo was transferred into them.
• This treatment was continued up to 100 days of gestation if the mare was found to be pregnant after 20 days.
• In total, seven transfers were performed.

Findings

• Three of the four mares were successful in getting pregnant and they carried to term, giving birth to live foals.
• The birth process, lactation, and maternal behaviour of these mares were normal, in spite of their lack of ovaries.
• The hormone levels (oestrogen, LH, or FSH) in the mares’ blood did not show any significant differences between pregnant and non-pregnant mares from the day of transfer (Day 7) to Day 20.
• However, from Day 36, there was a rise in LH hormone levels in pregnant mares, indicating the production of horse chorionic gonadotropin (CG). The oestrogen levels remained low until Day 50.

Conclusion

• The research concludes that the use of progesterone can establish and sustain pregnancy in mares without ovaries, with pregnancy and childbirth processes occurring normally.