Vitrification of Large Volumes of Stallion Sperm in Comparison With Spheres and Conventional Freezing: Effect of Warming Procedures and Sperm Selection.

This study compared different methods of freezing stallion sperm to ascertain the most effective technique. Results showed that vitrifying the sperm using spheres yielded better sperm quality than conventional freezing or vitrification in straws and single-layer centrifugation had potential to further enhance sperm quality in 0.5 mL straws.

Objective and Methods of the Research

• The main purpose of this research was to examine three different methods of freezing stallion sperm: vitrification using spheres, conventional freezing, and vitrification using straws. The sperm was vitrified by plunging 30μL of sperm (spheres) or 0.5mL straws into liquid nitrogen (LN), and conventional freezing was done using 0.5mL straws frozen in LN vapors.
• Additionally, the research also explored the impact of two different warming procedures (42°C for 20 seconds; 60°C for 15 seconds) and single-layer centrifugation (SLC) on the quality of sperm vitrified in straws.

Study Findings

• Vitrification using spheres produced significantly better results as compared to both conventional freezing and vitrification using straws. This was based on comparisons of total and progressive sperm motility, as well as plasma membrane and acrosome integrity. These aspects are vital to the function and fertility of the sperm.
• The researchers did not find any significant differences in sperm quality between the two warming procedures applied on the sperm vitrified in straws.
• However, the study revealed that single-layer centrifugation (SLC) performed after warming at 42°C for 20 seconds achieved higher values in sperm quality metrics than unselected samples.
• Meanwhile, SLC after 60°C for 15 seconds had an increased effect on total motility and plasma membrane integrity but didn’t affect other metrics.

Conclusions Drawn From the Study

• The conclusions drawn from the study were that sphere vitrification surpassed other methods in preserving stallion sperm quality.
• The data suggested that the warming procedures did not significantly affect sperm quality. However, using single-layer centrifugation after warming could potentially enhance sperm quality when vitrification was performed using 0.5mL straws.
• This research paves the way for further studies to optimize sperm vitrification methods, especially with the use of single-layer centrifugation, which could form an integral part of the sperm vitrification process to boost sperm quality after vitrification.