Retrospective analysis of commercial heterospermic and homospermic cooled boar semen: Effect of the season, sample type and shipping temperature on sperm quality

We retrospectively analysed data from heterospermic and homospermic boar semen for motility and morphology during a 2-year period. Homospermic doses were also evaluated for viability, acrosome integrity, DNA fragmentation, osmolality and pH. Additionally, we investigated the effect of temperature upon arrival and the agreement between viability and motility as evaluating tool. We observed lower (p < .05) total motility (TM) and normal sperm morphology within summer and fall. Conversely, lower (p < .05) progressive motility (PM) was found at the beginning and end of each year. Viability and acrosome integrity were reduced (p < .05) in summer months but not exclusively, suggesting that samples could be compromised by transport temperature. Sperm DNA fragmentation was <6% with a small variation. Medium osmolality and pH slightly changed (p < .05). Sperm count was not source of variation on sperm parameters. Sample temperature upon arrival correlated with PM and VSL (p < .05), while motility was reduced <12°C (p < .05). Homospermic doses were less affected by season and arrival temperature, having better parameters (p < .05) than contemporaneous heterospermic samples but influenced by genetic line (p < .05). We found a high agreement between viable acrosome-intact sperm and TM, especially when TM was ≥80%. Our data verify the improvement of sperm quality during time as sperm count/dose does not affect quality, but season effect persists regardless of ejaculate selection at the stud. Homospermic doses exhibited better parameters than heterospermic doses, seemingly being more resilient to temperature variations, suggesting that selection for sperm quality within boars selected by growth traits can improve the product quality.