Birth of a foal after oocyte transfer to a nonovulating, hormone-treated recipient mare.

The research demonstrated the successful birth of a foal using an oocyte (a cell in an ovary which can undergo meiosis to form an ovum) transferred to a nonovulating, hormone-treated mare, a first of its kind in any domestic species.

Suppressing Ovarian Activity

• The recipient mare, a horse not currently undergoing ovulation, had her ovarian activity suppressed with progesterone and estrogen treatment.
• The treatment prevented the mare from releasing eggs, preparing her to receive an oocyte from a donor mare.

Oocyte Transfer

• Post the hormonal treatment, estrogen was administered for three days before the transfer of the oocyte.
• The oocyte was extracted from a follicle in a donor mare and transferred to the recipient mare via flank laparotomy, a surgical procedure wherein an incision is made in the mare’s abdominal wall to reach the reproductive tract.

Insemination and Pregnancy Maintenance

• The recipient mare was inseminated seven hours before the transfer of the oocyte.
• Post the oocyte transfer, the recipient mare was treated with intramuscular progesterone from the day following the transfer till the 47th day after transfer. This was done to support pregnancy till placental progesterone production takes over.
• The recipient was further treated with altrenogest, a synthetic progesterone, orally until the gestation period of 150 days.

Birth and Progeny Confirmation

• At 321 days of gestation, a normal and healthy foal (colt) was born.
• DNA analysis was conducted to verify the progeny, which confirmed that the newborn colt was the offspring of the donor mare.
• This represents the first report of successful fertilization and term development of an embryo following oocyte transfer to a nonovulating mare and is a significant milestone in reproductive biology.