Post-thawing Sperm Quality in Chilean Purebred Stallions: Effect of Age and Seasonality.

This research investigates how the age of Chilean Purebred Stallions and the season in which their semen is collected affect the quality of the sperm after it is thawed. The study found that younger stallions produced higher quality sperm in the summer, while older stallions’ sperm quality decreased, particularly in the winter.

Research Objectives and Methodology

• The purpose of this research was to explore how the age of Chilean Purebred Stallions and the season in which their semen is collected (summer or winter) could impact the quality of the sperm post-thawing.
• This study was conducted due to the lack of previous investigations chronicling the relationship between age, seasonality and the freezing capability of the semen from CPS, a breed that has the oldest lineage in South America.
• To conduct the research, 20 fertile CPS were divided into three groups based on age: young, middle-aged, and aged. Using an artificial vagina, ten ejaculates were collected from each stallion during the summer (December) and winter (July) seasons and then frozen.
• Following freezing, the semen was thawed and examined under two forms of assessment: a computer-assisted semen analysis and a flow cytometer. The ability of the sperm to move forward (progressive motility), their average speed (velocity), and fragmentation of their DNA was analyzed.
• To determine statistical differences among the groups, the researchers used the Kruskal-Wallis test and Pearson’s correlation.

Key Findings

• The study revealed that the quality of the sperm, measured through mobility traits, diminished progressively with the age of the stallions and the seasonality. The worst performers were the aged group during winter, while the top performers were the young group in summer.
• Fragmentation of DNA in the spermatozoa increased significantly with the age of the stallions and seasonality, peaking in the stallions in the aged group during winter and dipping in the stallions in the young group during summer.
• Post-thawing sperm quality displayed a negative link with the age of the stallions, and a positive correlation with normal sperm morphology prior to freezing.

Conclusion

• Based on the research outcomes, it can be concluded that age and seasonality play significant roles in sperm quality after thawing, and hence should be taken into account while selecting CPS for reproductive programs. The study provides invaluable insights for those in the reproductive industry who work with CPS.