Colloidal centrifugation of stallion semen results in a reduced rate of sperm DNA fragmentation

Abstract

Stallion spermatozoa recovered and examined immediatelyafter colloidal centrifugation resulted in a higher straight-linevelocity (VSL) than sperm processed using direct conven-tional centrifugation (p = 0.000), but there was nodifferences in the progressive motility or sperm DNAfragmentation (SDF) as determined by the sperm chromatindispersion assay. However, when centrifuged spermatozoawere incubated at 37°C for 24 h to determine the rate of SDF(r-SDF), a lower r-SDF (p = 0.0011) was observed in thosesperm recovered after colloidal separation (0.5 ± 0.1%⁄h)compared to direct (1.2 ± 0.4%⁄h) or no centrifugation (r-SDF = 1.2 ± 0.3%⁄h). These results confirm that colloidalseparation of stallion spermatozoa results in prolonged spermDNA longevity, but these differences were only apparentfollowing a period of incubation and dynamic assessment.Consequently, we strongly recommend the use of thedynamic form of the SDF assay for evaluating centrifugationand⁄or otherex vivoprocedures, as a single basal assessmentof SDF may inadvertently result in a false-positive evaluationof DNA quality.