Deep freezing of horse embryos

Area of Science:

• Veterinary Science
• Reproductive Biology
• Cryobiology

Background:

• Non-surgical embryo recovery in horses is established.
• Cryopreservation is a key technology for equine germplasm preservation.
• Optimizing cryopreservation protocols is crucial for improving success rates.

Purpose of the Study:

• To evaluate the efficacy of slow-freezing horse embryos at two different cooling temperatures.
• To assess the viability and developmental potential of cryopreserved horse embryos after thawing.

Main Methods:

• Horse embryos (Days 6-8 post-ovulation) were non-surgically recovered.
• Embryos were cooled slowly to -35°C or -40°C and stored in liquid nitrogen.
• Thawed embryos were surgically transferred to synchronized recipient mares.

Main Results:

• Four pregnancies were established from the transferred embryos.
• Only one mare carried her pregnancy to term, resulting in a live foal.
• Survival rates were low, indicating challenges in cryopreservation efficacy.

Conclusions:

• Slow-freezing horse embryos to -35°C or -40°C resulted in limited success for establishing viable pregnancies.
• Further research is needed to optimize cryopreservation protocols for equine embryos.
• Cryopreservation remains a valuable tool but requires refinement for routine application in equine reproduction.