Anti‐oxidative Effects of Ethanol Extract of Origanum vulgare on Kinetics, Microscopic and Oxidative Parameters of Cryopreserved Holstein Bull Spermatozoa

Origanum vulgare contains high levels of phenolic compounds such as gallic acid and polyphenols such as rosmarinic acid and quercetin. The purpose of this study was to investigate the effects of Origanum vulgare extract, as a natural antioxidant, on freezing-thawing semen quality in Holstein bulls. Three Holstein bulls (5-6 years old, mean live weight 800 kg) were used for semen collection twice a week for two months. Ethanol extract of Origanum vulgare (2, 4, 8, 12, 16 and 20 mL/dL extender) was added to a citrate-yolk-base extender. After freezing-thawing sperm motility parameters, viability and membrane integrity were determined using a CASA system, eosin-nigrosin staining, and hypo-osmotic swelling test, respectively; malondialdehyde concentration and activity of superoxide dismutase and catalase were also measured. The percentages of motility were higher (P 0.05) in the freezing extender containing 4 mL/dL Origanum vulgare extract (72.34±7.98). Addition of 2 and 4 mL/dL extract of Origanum vulgare significantly improved the motility, viability and plasma membrane integrity of the spermatozoa following freezing-thawing process compared to the control group. Addition of 4 mL/dL extract significantly reduced the concentration of malondialdehyde compared to the control group (P 0.05). The activity of superoxide dismutase and catalase increased significantly by inclusion of 4 and 8 mL/dL extract of Origanum vulgare to the extender (1.86±0.18 and 1.92±0.28 U/mg protein; 4.54±0.13 and 4.28±0.28 U/mg protein, respectively). The activity of superoxide dismutase and catalase was significantly increased by inclusion of 4 and 8 mL/dL extract to the extender. In conclusion, addition of 2 and 4 mL/dL extract of Origanum vulgare to the semen extender improved the post-thawed quality of semen, which may be due to increasing in antioxidant enzyme activity and reduction in lipid peroxidation.