Association between myeloperoxidase concentration in equine frozen semen and post-thawing parameters.

The research uncovers the correlation between a pro-oxidant enzyme, myeloperoxidase (MPO), and the quality of frozen semen in stallions, revealing that high concentrations of MPO negatively affect the post-thawing parameters of the semen.

Objectives of the Research

The study aimed to assess the impact of MPO, a potent enzyme contributing to oxidative damage, on the characteristics of frozen stallion semen following thawing. The objective was to:

• Measure the MPO concentration in post-thaw semen samples from different stallions.
• Analyze the correlation between MPO concentration and semen characteristics, including sperm concentration, total and progressive motility.
• Examine the relationship between MPO levels and sperm abnormalities.

Methodology

The researchers used an enzyme-linked immunosorbent assay (ELISA) to measure the MPO concentration in thirty-five different semen samples post-thawing. Other parameters examined were:

• Post-thawing spermatozoal concentration, and progressive and total motility, using computer-assisted semen analysis.
• Percentage of live spermatozoa and abnormal forms using Eosin-Nigrosin and Diff-Quick® staining.
• Freezability of semen, determined by post-thawing progressive motility.

Findings

The findings of the study suggest that the presence of high amounts of free MPO in thawed semen correlates with two key parameters.

• High MPO concentrations were associated with reduced total and progressive motility in the sperm samples. In other words, sperm in samples with more MPO were less able to move quickly and effectively.
• A high concentration of MPO was also linked to a greater proportion of sperm abnormalities, especially regarding head shape and acrosome reactions.

Conclusions

The study concluded that MPO could have a potential harmful effect on the total and progressive motility of horse semen, with a high concentration of MPO associated with poorer sperm quality. They also uncovered a clear negative correlation between normal motile forms and MPO concentration. However, the researchers stipulate that more work is still required to determine the exact effect of MPO on dead or abnormal sperm forms. This research provides valuable insights for equine reproduction and the ongoing issue of sub-optimal semen freezability.