Lycopene and alpha-lipoic acid improve semen antioxidant enzymes activity and cashmere goat sperm function after cryopreservation

Cashmere goats, a unique biological resource in China, have the highest cashmere yield and best fiber quality in the world. The goal of this study was to determine the effects of cryopreserving with lycopene (LP) and alpha-lipoic acid (ALA) on the physiological characteristics of Cashmere goat spermatozoa. The results showed that sperm motility, acrosome integrity, membrane integrity, and mitochondrial activity of goat spermatozoa were greater in extenders containing 1.0 mg/mL LP and 10 μg/mL ALA (P < 0.05). Furthermore, higher SOD, CAT, and GSH-Px levels in semen occurred for extenders with 1.0 mg/mL LP and 10 μg/mL ALA compared with that of other treatments and the control group (P < 0.05). Interestingly, this study also combined LP + ALA in the extender. The results showed that the sperm motility, membrane integrity, and acrosome integrity in 1.0 mg/mL + 5 μg/mL in the LP + ALA group were significantly elevated compared with that of the control group (P < 0.05). Moreover, 1.0 mg/mL + 5 μg/mL LP + ALA addition increased SOD, CAT, and GSH-Px in spermatozoa more than 1.0 mg/mL LP and 10 μg/mL ALA (P < 0.05). In addition, the results of AI showed that the pregnancy rates were higher in the 1.0 mg/mL + 5 μg/mL LP + ALA group than the control group (P < 0.05). In conclusion, the addition of LP + ALA to extender solutions protects goat spermatozoa from ROS attack by improving antioxidant enzymes activity, and the results suggested that freezing extenders supplemented with 1.0 mg/mL + 5 μg/mL LP + ALA would be beneficial to the Cashmere goat breeding industry.