Hysteroscopic or rectally guided, deep-uterine insemination of mares with spermatozoa stored 18 h at either 5 degrees C or 15 degrees C prior to flow-cytometric sorting.

This study explores the efficiency of techniques for storing and inseminating sex-selected stallion sperm, ultimately aiming for simplified methods for their application in the horse industry. It concludes that the necessity for stallions to be at the sorter location can be eliminated without affecting fertility rates, and that different storage temperatures and insemination techniques may influence pregnancy outcomes.

Objective and Background

• The researchers conducted a study on the storage and insemination of sex-selected stallion sperm.
• The objective was to simplify the method of inseminating mares with sex-selected sperm and make the technique more accessible for the horse industry.
• This is important because achieving good pregnancy rates with fresh, sex-sorted stallion sperm often requires the stallion to be present at the sorting location during breeding season, which makes the process complicated and inconvenient for many stallion owners.
• The insemination technique commonly used, hysteroscopic insemination, is complex and requires costly equipment and specially trained personnel, which is another challenge for the industry.

Methods

• The researchers stored stallion sperm at 5 degrees C or 15 degrees C for 18 hours prior to sex-sorting.
• They then inseminated 20 million sex-sorted sperms using either the hysteroscopic method or a simpler, less invasive method known as the rectally guided deep-uterine technique.
• Pregnancy results were assessed based on 16-day pregnancy status.

Findings

• The first-cycle pregnancy rate was 72% (18 out of 25) when sperm were stored at 15 degrees C, sex-sorted, and then inseminated using the hysteroscopic method.
• This suggests that the requirement for stallions to be present at the sorter location could be eliminated without compromising fertility rates.
• There was a trend towards higher pregnancy rates when the sperm were stored at 15 degrees C compared to 5 degrees C prior to sorting.
• Similarly, hysteroscopic insemination appeared to result in higher pregnancy outcomes compared to the rectally guided, deep-uterine technique.
• These trends suggest that further research with larger sample sizes might reveal significant differences between treatments.

Conclusion

• The study indicates that it may be possible to simplify the procedure for inseminating mares with sex-selected sperm, primarily by eliminating the need for stallions to be present during sperm sorting.
• Also, the choice of storage temperature and insemination technique may influence pregnancy outcomes, factors that warrant further investigation.