DNA integrity and kinetic parameters of ram sperm are preserved by Thymus persicus essential oil when stored frozen

Background: The study of storing cells at extremely low temperatures for long periods is called cryopreservation. Framers usually use frozen sperm. Objective: The aim of this study was to investigate effect of thyme on traits of frozen sperm. Methods: Sperm samples were collected twice weekly from four rams. First, progressive, non-progressive, concentration, viability, morphology, volume, and gross motility were assessed. Sperm samples were diluted with a diluent and enriched with Thymus persicus essential oil at concentrations of 0, 100, 200 and 400 µg/ml. Straws after cooling in refrigerator, were immersed in liquid nitrogen. Samples were thawed first and 30th days of experiment. Total motility, viability, abnormality, plasma membrane health, acrosome integrity, glutathione peroxidase, superoxide dismutase, DNA fragmentation, malondialdehyde and CASA were assessed on thawed days. Result: The results showed that addition of Thymus oil (100 µg/ml) had greatest impact on plasma membrane health, viability, CASA, progressive and total motility (p < 0.01) and GPx (p < 0.05). Thymus persicus was significantly increased at 100 and 200 µg/ml than other groups for SOD and decreased for MDA (p<0.01). DNA fragmentation at treated groups was significantly increased than control group (p<0.01) and there was significant increase in acrosome integrity at 400 µg/ml compared to the other groups (p <0.05). There was a significant decrease in viability and motility, HOST and SOD throughout the experiment, while there was a significant increase in non-progressive, abnormal and malondialdehyde (p<0.01). Conclusion: The results of current study showed that adding Thymus persicus to a diluent improved quality of sperm after freezing.