Prolonged maintenance of stallion semen by optimization of cooling conditions.
Authors: Guertin Jillian E, Losano Joao de Agostini, Salazar Sophia, Callaham Justin, Daigneault Bradford W
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Prolonged maintenance of stallion semen by optimization of cooling conditions Current commercial shipping containers for cooled stallion semen maintain viability for approximately 48 hours, creating significant logistical constraints for equine breeding programmes reliant on assisted reproductive technologies. Guertin and colleagues investigated whether externally regulating storage container temperature could extend semen viability by testing two pre-freezing protocols (-20°C and -80°C cooling cans) and monitoring sperm kinematics every 12 hours over 3.5 days, followed by a second experiment comparing ambient temperature storage against externally temperature-regulated conditions (5°C external environment) over up to 8 days. Semen cooled in -20°C pre-frozen cans significantly outperformed -80°C conditions, maintaining 63% total and 29% progressive motility at 60 hours versus 32% and 17% respectively; critically, internal monitoring revealed 20°C as the threshold beyond which motility declined rapidly. When Equitainers containing -20°C cans were placed in a 5°C external environment, total motility remained above 50% for more than 7 days—extending the usable storage window by approximately 144 hours compared with conventional practice. For practitioners involved in semen collection, shipment coordination and embryo transfer scheduling, these findings suggest that relatively modest modifications to external storage conditions could substantially improve reproductive programme flexibility and reduce the pressure to use semen immediately, whilst maintaining acceptable post-thaw survival rates.
Read the full abstract on PubMed
Practical Takeaways
- •Breeding programs can now extend cooled semen shipment viability beyond the traditional 48-hour window to 7+ days by maintaining external storage temperature at 5°C, reducing pressure for immediate breeding scheduling
- •Using -20°C (rather than -80°C) pre-frozen cooling cans in commercial shipping containers provides better sperm viability; keep internal container temperature below 20°C to prevent rapid motility loss
- •These findings directly improve logistics and success rates for equine breeding operations using shipped cooled semen, particularly for long-distance or international breeding programs
Key Findings
- •Stallion sperm maintained in Equitainers with -20°C cooling cans showed superior total and progressive motility (63%, 29%) compared to -80°C conditions (32%, 17%) at 60 hours
- •Internal temperature monitoring identified 20°C as the critical threshold above which sperm motility rapidly declined
- •External temperature regulation at 5°C extended cooled stallion semen viability to beyond 7 days while maintaining total motility above 50%, compared to traditional 48-hour storage limits
- •Optimization of cooling container temperature management can significantly extend the practical storage window for shipped stallion semen in equine reproductive programs