Optimization of cryopreservation protocols for cooled-transported stallion semen

Area of Science:

• Animal Science
• Reproductive Biology
• Cryobiology

Background:

• Standardized protocols for freezing cooled-transported stallion semen are lacking.
• On-farm collection and processing of stallion semen for shipping require optimized freezing methods.

Purpose of the Study:

• To optimize and simplify protocols for freezing cooled-transported stallion semen.
• To evaluate the effects of centrifugation temperature and different semen freezing extenders on post-thaw sperm quality.

Main Methods:

• Cooled-transported stallion semen was centrifuged at room temperature or 5°C.
• Semen was cryopreserved using three different extenders: improved modified French formula, Botucrio, and improved lactose-EDTA.
• Semen was frozen conventionally or in an ultra-freezer (-80°C).
• Sperm variables including motility, membrane integrity, and acrosome integrity were assessed post-thaw.

Main Results:

• Centrifugation temperature (room temperature vs. 5°C) did not affect post-thaw semen quality.
• Botucrio and lactose-EDTA extenders resulted in significantly better post-thaw total and progressive motility compared to the modified French formula.
• Lactose-EDTA yielded a higher percentage of intact sperm membranes than the modified French formula.
• Freezing in an ultra-freezer reduced post-thaw sperm motility but not membrane or acrosome integrity.

Conclusions:

• Centrifugation and extender addition can be performed at room temperature or 5°C.
• Botucrio and lactose-EDTA extenders are recommended for conventional cryopreservation of cooled-transported stallion semen.
• The modified French formula is less suitable for cryopreserving cooled-transported stallion semen.