Motility and Fertility Evaluation of Thawed Frozen Stallion Semen After 24 Hours of Cooled Storage.

The researchers are investigating the viability and fertility of frozen stallion semen after it has been thawed and stored at low temperatures for 24 or 48 hours. The study found that the semen maintained adequate motility and fertility, opening up new implications for horse breeding practices.

Research Methodology

• Eight ejaculates from stallions are collected for the experiment. Portions of these samples are cooled in INRA96 and CryoMax LE minus cryoprotectant with a sperm concentration of 50 million total sperm/mL. The rest is frozen in a CryoMax LE extender at 200 million total sperm/mL concentration.
• The semen is then thawed using one of three thawing protocols. After thawing, it is diluted to a concentration of 50 million total sperm/mL in either INRA96 or CryoMax LE minus cryoprotectant again and cooled to a temperature of 5°C.
• The motility of the sperm is evaluated after 24 and 48 hours of this cooling process.

Insemination and Fertility Evaluation

• Eight mares are then inseminated over the course of two estrous cycles using the previously frozen semen, thawed, extended in INRA96, and cooled for 24 hours.
• The fertility potential of the semen is assessed by observing the pregnancy rate achieved from these inseminations.

Research Findings

• The study found that there was no difference in the progressive motility of the sperm at 24 or 48 hours after the cooling process, regardless of which thawing protocol was used.
• Furthermore, the study reported a significant per cycle pregnancy rate of 56% (9 out of 16 cycles) using the semen that was frozen, thawed, extended, and cooled for 24 hours.
• In summary, the study found that frozen stallion sperm, after being thawed, extended, and cooled to 5°C for 24 hours, maintained an adequate motility rate of over 30% and substantial fertility potential.

Conclusion

• The research provides valuable insights into how the storage, thawing, and cooling processes affect the viability and fertility of cryopreserved stallion semen. The results suggest that it’s possible to maintain sufficient sperm motility and achieve a substantial pregnancy rate even after the semen has been frozen, thawed, and cooled for a certain period.
• These findings could have significant implications for horse breeding practices as they pose new possibilities for efficient storage and use of frozen stallion semen.