Effects of Apigenin and Astragalus Polysaccharide on the Cryopreservation of Bull Semen

SIMPLE SUMMARY: Oxidative stress in mammalian sperm can be induced during cryopreservation; therefore, it is important to inhibit oxidative stress to maintain sperm motility during cryopreservation. The present study was performed to investigate the effects of supplementing apigenin (AP), astragalus polysaccharide (APS), or their combination on an extender for bull semen freezing. Sperm viability, motility, and motion parameters; acrosome integrity and membrane integrity; endogenous antioxidant indices; and reactive oxygen species (ROS) and malondialdehyde (MDA) levels were evaluated after semen thawing. Our results indicated that 0.2 mmol/L AP or 0.5 mg/mL APS improved the cryopreservation of bull sperm; moreover, their combination in the extender could further improve the protective effects on bull sperm post-thaw. ABSTRACT: The purpose of this study was to determine the effects of apigenin and astragalus polysaccharides on the cryopreservation of bovine semen. Apigenin, astragalus polysaccharides, or their combination were added to a frozen diluent of bovine semen. Afterwards, Computer Assisted Semen Analysis (CASA), membrane functionality, acrosome integrity, mitochondrial integrity, CAT, SOD, GSH-Px, MDA, and ROS detection were conducted. The results showed that adding 0.2 mmol/L AP or 0.5 mg/mL APS could improve the quality of frozen sperm. Compared to 0.2 mmol/L AP alone, the combination of 0.2 mmol/L AP and 0.3 mg/mL APS significantly increased the total motility (TM), average path distance (DAP), straight line distance (DSL), average path velocity (VAP), curvilinear velocity (VCL), wobble (WOB), and sperm CAT and SOD levels (p < 0.05), while reducing the ROS and MDA levels (p < 0.05). These results indicated that the addition of 0.2 mmol/L AP or 0.5 mg/mL APS alone has a protective effect on the freezing of bovine semen. Compared to the addition of 0.2 mmol/L AP, a combination of 0.2 mmol/L AP and 0.3 mg/mL APS could further improve the quality of frozen semen.