Centrifugal force assessment in ram sperm: identifying species-specific impact

Background Centrifugation is routinely employed in handling the ejaculates of some species, but it is not part of the commonly used protocols in ram. However, the development and implementation of new assisted reproductive technologies, alternative preservation models based on washing sperm from a cellular ageing-accelerating substance such as the seminal plasma, and basic studies in spermatology is associated with the use of centrifugation. This requires a specific evaluation of the centrifugation protocols considering the species-specific relationship with the potential damage produced by this procedure. No previous studies have determined the effect of different centrifugation forces on ram sperm. Therefore, we aimed to assess the performance of three centrifugal forces (600xg, 3000xg, and 6000xg for 10 min at room temperature) and their effects on ram sperm motility and functionality. Results Sperm motility and functionality parameters were assessed at 0 h and after 2 h of incubation at 37 degrees C. As expected, a higher cell packaging degree was obtained at high centrifugation forces (P <= 0.0001). Cell packaging was unstable at all centrifugal forces. Thus, there was a high cell resuspension rate after less than 2 min. Regarding sperm quality, there was a change in movement pattern of 3000xg and 6000xg centrifuged sperm after 2 h of incubation at 37 degrees C, characterized by an increase in rapid progressive motility, linearity, straightness, and beat frequency, and a decrease in medium progressive motility, curvilinear velocity, path velocity, and head lateral amplitude. Non-significant differences were obtained among the different treatments concerning the total viability. However, we observed a significant increase (P <= 0.05) in the percentage of viable apoptotic sperm in the samples centrifuged at 6000xg at 0 h. Conclusions Centrifugal forces equal to or greater than 3000xg induced some deleterious effects in ram sperm quality, and lower forces did not provide a successful cell packaging degree.

Automated summary

This study evaluated the effects of different centrifugal forces on ram sperm motility and functionality, showing that high centrifugal forces increased cell packaging degree but caused instability, while sperm centrifuged at 3000xg and 6000xg exhibited changes in movement pattern with increased linearity and beat frequency, as well as decreased velocity and path velocity after 2 hours of incubation at 37 degrees C.