Shipping duration and temperature influence the characteristics of cryopreserved horse semen stored in different shipping devices for up to 14 days.

The study explored the effects of storing frozen horse semen in two different conditions: a dry shipper (≤ -150 °C) and on dry ice (≤ -78 °C) for up to 14 days. The results showed that while semen can be safely stored on dry ice for up to 7 days, both storage methods negatively impacted sperm DNA integrity and mitochondrial function after 14 days.

Objective

• Examine the impact of storing horse semen in a dry shipper or on dry ice for a duration of up to 14 days.

Methodology

• 264 frozen semen straws from 8 male horses, initially stored in liquid nitrogen, were transferred to either a dry shipper or a dry ice styrofoam box on day 0 (d0).
• On specific days (d1, d3, d7, d10, and d14), straws from both storage methods were returned to the liquid nitrogen container.
• Assessment of semen included:
• Evaluation of total motility (TMot), progressive motility (PMot), and sperm velocity using CASA.
• Fluorescence microscopy to determine percentage of membrane-intact sperm, high mitochondrial membrane potential (HMMP), and DNA fragmentation.
• Continuous monitoring of the temperature inside the storage containers.

Results

• Up to day 7 (d7), no significant changes were observed in TMot, PMot, and membrane-intact sperm.
• After d7, these parameters decreased for semen stored on dry ice, but not in the dry shipper.
• HMMP consistently decreased over time in both storage methods, with a more pronounced decrease observed in the dry ice storage.
• DNA fragmentation increased on days 10-14 for semen stored on dry ice and on day 14 for semen in the dry shipper.

Conclusion

• Frozen horse semen can be safely stored on dry ice for up to 7 days without significant degradation.
• However, after 14 days, both storage methods (dry shipper and dry ice) negatively affected sperm DNA integrity and mitochondrial function.