Temperatures from 4 to 15 °C are suitable for preserving the fertilizing capacity of stallion semen stored for 22 h or more in INRA96 extender.

The study examined how stallion sperm’s capacity to fertilize can be maintained when stored in certain conditions and at temperatures between 4-15°C, for over 22 hours.

Experiment Setup

• The researchers conducted two main experiments to test how varying temperatures and air exposure affected the preservation of stallion’s semen diluted with INRA96 extender.
• The first experiment, under laboratory conditions, assessed the impacts of 72-hour storage at 5°C with air, versus 15°C without air.
• In the second experiment, set under field conditions, the team subjected the semen samples to 22 hours’ storage without air at four different ambient temperatures, in disposable containers.

Assessment and Observation

• The concluding fertility was gauged by measuring the ‘per cycle pregnancy rate’ (PC) after a single artificial insemination into a mare’s uterus, performed either 7 hours prior to ovulation (in Experiment 1) or 17 hours prior (in Experiment 2).
• The researchers observed that, in Experiment 1, the fertility rate was similar for both the 5°C and 15°C conditions.
• However, in Experiment 2, a notably decreased PC was seen when the semen was stored at cooler ambient temperatures (around 0°C), compared to intermediate (around 4 to 7°C) or high (around 8 to 10°C) temperatures.

Conclusion

• The results of this research demonstrated that stallion sperm can withstand a fair range of positive temperatures, as well as air exposure for 22 hours or more without losing fertilizing capacity.
• However, critically, temperatures approaching 0°C negatively impacted equine fertility.
• Such findings highlight potential ways to improve the efficacy and convenience of storing and transporting stallion semen for breeding purposes.