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

SIMPLE SUMMARY: The bull accounts for a great part of the economic value of beef herds managed with natural service. Therefore, the bull breeding soundness evaluation (BBSE) becomes essential in such cattle herds. Part of BBSE is the semen-quality evaluation (classical and kinetic parameters), which can be performed in situ (by trained practitioners) or at laboratories, with semen being short-term stored and shipped. The extender used, storage temperature, and duration may affect its quality. Thus, our aim was to explore this in order to define the best conditions to preserve seminal quality, to be reliably assessed afterwards. Semen quality was preserved for up to 4–6 h post-ejaculation, except for INRA96(®) (IMV Technologies, L’Aigle, France) at 5 °C. Motility decreased from 4 to 6 h up to 24 h, with the best values obtained with BIOXcell(®) (IMV Technologies, L’Aigle, France) at 5 °C. Microbiological load was stable over time with AndroMed(®) (Minitub Ibérica SL, Tarragona, Spain) and BIOXcell(®), and increased at room temperature with INRA96(®). Therefore, we suggest to evaluate seminal quality as soon as possible. However, using AndroMed(®) and BIOXcell(®), either at 5 °C or room temperature, semen can be reliably evaluated for up to 6 h, while INRA96(®) can be used at room temperature. These results help to fix adequate protocols for short-term storage and shipment of bovine semen collected under field conditions. ABSTRACT: 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.