Effect of Extender, Storage Time and Temperature on Kinetic Parameters (CASA) on Bull Semen Samples.

CASA kinetic parameters are often evaluated in a diagnostic centre. How storage conditions affect ejaculates up to evaluation is unclear. We assessed, in 25 commercial bulls electroejaculated in the field, the impact of time until evaluation (0-2 h, 4-6 h, and 24 h post-ejaculation), holding temperature (5 °C vs. room temperature), and extender (AndroMed, BIOXcell or INRA96) on CASA kinetic parameters. Total and progressive motility, VCL, VAP, VCL, ALH, BCF, STR, LIN, and WOB were assessed. CASA kinetic parameters were preserved for up to 4-6 h post-ejaculation, except for AndroMed. Regardless of extender or temperature, motility decreased from 4-6 h up to 24 h, with the best values obtained with BIOXcell at 5 °C. Our results suggest that BIOXcell can preserve sperm motility for up to 6 h, either at 5 °C or room temperature, and also INRA96 at room temperature, with motility assessments and the percentage of the most rapid sperms being the lowest with INRA96 at 5 °C. The kinetic parameters decreased when analyses were performed at 24 h. Therefore, we suggest evaluating seminal quality as soon as possible, before 6 h after collection. These results help to fix adequate protocols for the short-term storage and shipment of bovine semen collected under field conditions.