Deep freezing of sheep embryos.

Area of Science:

• Veterinary Science
• Reproductive Biology
• Cryobiology

Background:

• Sheep embryo collection and handling are crucial for reproductive technologies.
• Cryopreservation is a key technique for preserving genetic material and improving breeding efficiency.

Purpose of the Study:

• To evaluate the viability of sheep embryos after cryopreservation using dimethyl sulfoxide (DMSO).
• To determine optimal thawing rates for cryopreserved sheep embryos to maximize survival and development.

Main Methods:

• Sheep embryos (Days 5-8) were treated with 1-5 M-DMSO and subjected to various cooling and thawing rates.
• Embryo viability was assessed by transfer to rabbit oviducts.
• Successful embryos were transferred to recipient ewes to determine pregnancy and lambing rates.

Main Results:

• Embryos survived short-term exposure to DMSO at 0°C.
• High survival rates (12/14) were observed after freezing to -15°C to -60°C and thawing at 12°C/min.
• Thawing at 12°C/min yielded the highest normal development rate (10/36) after ultra-low temperature freezing, resulting in live lambs.

Conclusions:

• Cryopreservation of sheep embryos using DMSO is feasible and effective.
• Thawing rate significantly impacts embryo survival and developmental potential.
• This technique holds promise for enhancing sheep artificial insemination and embryo transfer programs.