Coenzyme Q10 Improves Functional and Structural Parameters of Dairy Goat Sperm During Cooling and Cryopreservation

Cryopreservation of gametes is crucial for conserving genetic diversity in livestock and endangered species, but the process can significantly impair sperm quality due to oxidative stress. Our aim was to evaluate the impacts of coenzyme Q10 (CoQ10) supplementation on the in vitro quality of cooled and cryopreserved goat semen. Semen samples collected from six mature Saanen bucks were pooled then diluted with AndroMed^® semen extender to a final concentration of 800 × 10⁶ sperm/mL. Diluted semen was supplemented with 0, 1, 2, 5, 10, and 20 µM CoQ10. Extended semen was either cooled at 4 °C for 72 h or cryopreserved using a Styrofoam box in which the straws were arranged on the freezing rack and placed 4 cm over the liquid nitrogen (LN₂) for 10 min then stored in a LN₂ tank for one-week before being thawed at 37 °C for 30 sec. Sperm quality, including total and progressive motility, sperm kinematics, live sperm %, and sperm membrane integrity, was assessed at 0 h (fresh semen), and 24, 48, and 72 h post-cooling. For post-thaw sperm, we evaluated the same parameters plus acrosome integrity, mitochondrial activity, lipid peroxidation, and sperm ultrastructural changes using scanning electron microscopy (SEM). The pooled semen sample was considered the experimental unit for all treatments. Cooled semen data were analyzed using a General Linear Model (GLM) with univariate analysis, followed by Tukey's test for multiple comparisons. In contrast, data from frozen-thawed semen were analyzed using one-way analysis of variance (ANOVA) followed by Tukey's test. CoQ10 supplementation at 10 and 20 µM significantly (p < 0.05) improved sperm motility, viability, and membrane integrity in cooled and frozen-thawed semen in comparison with the control group (0 µM CoQ10). Moreover, the same concentrations significantly (p < 0.05) enhanced acrosome integrity, mitochondrial activity, and reduced the percentages of sperm with lipid peroxidation in frozen-thawed semen. Furthermore, 10 and 20 µM CoQ10 significantly mitigated the ultrastructural defects in frozen-thawed spermatozoa. In conclusion, CoQ10 supplementation during the cooling and cryopreservation of dairy goat semen significantly improved sperm quality. Among the tested concentrations, 10 and 20 µM exhibited the most favorable outcomes.