The Effect of Coenzyme Q10 and α-Tocopherol in Skim Milk-Based Extender for Preservation of Caspian Stallion Semen in Cool Condition

The purpose of this study was to determine the effects of different concentrations of coenzyme Q10 (CoQ10) and α-tocopherol (T) along with their interaction effects on the quality of preserved stallion semen at 5°C for a period of 48 hours. Semen was collected and diluted with skim milk-based extender that was supplemented with different antioxidants: no antioxidant (negative control [NC]), 0.9% (vol/vol) dimethyl sulfoxide (positive control [PC]), α-tocopherol (5 [T5] or 10 [T10] mM), CoQ10 (1 [C1] or 2 [C2] μM), 1 μM CoQ10 + 5 mM α-tocopherol (C1T5), 1 μM CoQ10 + 10 mM α-tocopherol (C1T10), 2 μM CoQ10 + 5 mM α-tocopherol (C2T5), and 2 μM CoQ10 + 10 mM α-tocopherol (C2T10), then kept at 5°C. The results showed that C1 extender resulted in higher total motility (62.44 ± 3.82) and plasma membrane integrity (65.16 ± 3.63%) compared with NC after 48 hours of storage (P < .05). Different concentrations of α-tocopherol had no significant effects on sperm quality, with the exception of plasma membrane integrity, compared with NC and PC extenders (P > .05). Also, C1T5 extender improved total and progressive motility, plasma membrane integrity and functionality, and decreased lipid peroxidation compared with NC and C2T10 extenders over 48 hours of storage at 5°C (P < .05). The C1T5 extender was similar to C1 and T5 extenders in all semen parameters evaluated during storage time. In conclusion, between previously mentioned extenders, C1T5 could improve stallion sperm quality during 48 hours of storage. In the present study, none of extenders had effect on sperm quality until 24-hour storage.