Single-Layer Colloid Centrifugation as a Method to Process Urine-Contaminated Stallion Semen After Freezing-Thawing.

The research article investigates the viability of using a single-layer colloid centrifugation method to process frozen and then thawed horse semen that has been contaminated with urine. The findings reveal that although urine contamination significantly reduces semen motility, the centrifugation method could successfully salvage semen with improved motility and viability in samples with low contamination.

Objective and Methodology

• The objective of this study is to examine the effectiveness of a single-layer colloid centrifugation (SLC) process to process frozen-thawed stallion semen contaminated with urine.
• Urospermia, a condition in which urine mixes with semen during ejaculation, is a significant problem affecting stallions.
• Previously, it was believed that contaminated semen could not be cryopreserved. However, this study seeks to challenge this belief.
• Semen samples (n = 55) from eight stallions were divided into three groups based on the level of urine contamination: no urine, low (20%) and high (50%).
• The semen was then extended, cushion-centrifuged and subsequently suspended in BotuCrio, which is a cryoprotective medium, at a concentration of 200 million sperm/mL.
• The prepared samples were then cryopreserved in liquid nitrogen, thawed, and finally processed through single-layer colloid centrifugation.

Analysis and Findings

• Researchers assessed total motility (TM), progressive motility (PM), sperm viability (%VIAB) and yield before and after the centrifugation process using a computer-assisted semen analysis tool and NucleoCounter.
• Data was analysed using two-way ANOVA and Tukey’s test to measure statistical significance.
• Findings showed that total and progressive motility decreased as the level of urine contamination increased.
• A slight reduction in sperm viability post-cryopreservation was observed with increased urine contamination.
• Recovery rates of sperm after centrifugation were not significantly different between the groups.

Conclusion

• In conclusion, the study found that urine contamination affects sperm motility in a dose-dependent manner. The more urine present, the lower the motility.
• The use of post-thaw SLC could select sperm with higher motility and viability in control and low groups, but it only selected sperm with a higher viability in the high group.
• Overall, the results suggest that using single-layer colloid centrifugation could be an effective method to process stallion semen contaminated with urine, especially in low contamination cases.