Effects of Extender Type, Storage Time, and Temperature on Bull Semen Parameters.

Seminal parameters can be evaluated in situ, or samples can be delivered to 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 semen quality. Acrosome integrity, sperm viability and morphology, CASA-total and progressive motility, pH, and colony-forming units were assessed. Semen quality was preserved for up to 4-6 h post-ejaculation, except for INRA96 at 5 °C. Regardless of extender or temperature, motility decreased from 4 to 6 h up to 24 h, with the best values obtained with BIOXcell at 5 °C. pH differed from 4 to 6 h up to 24 h, acidifying when stored at room temperature. Microbiological load was stable over time with AndroMed and BIOXcell, and increased at room temperature with INRA96. Our results suggest that AndroMed and BIOXcell can preserve semen quality for up to 6 h, either at 5 °C or room temperature, while INRA96 only at room temperature. These results help to fix adequate protocols for short-term storage and shipment of bovine semen collected under field conditions.