Evaluation of the function of fresh and frozen-thawed sex-sorted and non-sorted stallion spermatozoa using a heterologous oocyte binding assay.

The research analysed the effectiveness of both fresh and frozen-thawed, sex-sorted and non-sorted stallion sperm in binding to bovine oocytes, using a heterologous sperm-binding assay. The study concluded that all types of sperm had the capability to attach to bovine oocytes, indicating they are functionally capable for fertilisation.

Introduction to the Study

• The purpose of this study was to explore the fertilisation potential of fresh and frozen-thawed stallion spermatozoa, which were either sex-sorted or non-sorted. This was to measure their ability in binding to bovine oocytes, which was used as a test for fertilising capacity.
• This test, known as a heterologous sperm-binding assay, was used due to the absence of effective IVF procedures for horses.

Methodology

• The study analysed four groups of spermatozoa: fresh non-sorted, fresh sex-sorted, frozen-thawed non-sorted, and frozen-thawed sex-sorted retypes.
• Spermatozoa that were found in association with the zona pellucida of bovine oocytes were categorised as either ‘attached’ or ‘bound’, based on whether they were acrosome intact or acrosome reacted.

Findings

• The results showed that there was a significantly lower number of frozen-thawed spermatozoa attached to the oocytes in comparison to fresh spermatozoa.
• No significant difference was identified in the number of attached sex-sorted and non-sorted frozen-thawed spermatozoa.
• Interestingly, a significantly higher number of sex-sorted fresh spermatozoa were found attached to the oocytes after one hour of coincubation, but after three hours, this difference was no longer noticeable.

Conclusion

• Based on the findings, the study concluded that both fresh and frozen-thawed, sex-sorted and non-sorted stallion spermatozoa are functionally capable of attaching and binding to bovine oocytes in vitro.
• The research also discovered that fresh sex-sorted spermatozoa attached better than non-sorted spermatozoa. This suggests that sex-sorted spermatozoa may have a more advanced capacitation-like status.