Combined n-3 Fatty Acids and α-Tocopherol Supplementation Improved the Ovine Sperm Cryosurvival

Abstract

Background: Spermatozoa preservation is an approach to improve the fertility rate to pass on the valuable genetic material from sire to their offspring. During the last 20 years, reproductive biotechnologists have focused on the approaches that improve spermatozoa cryosurvival. One of the possible mechanisms is supplementation in semen extender. Objectives: The aim of this study was to evaluate the combined effects of healthy ram semen with n-3 fatty acids and α-tocopherol (Vitamin E) on freezing ability and fatty acid (FA) content of sperm cell. Materials and Methods: Semen collection was performed on six mature Zandi rams by an artificial vagina. In the present study, two experiments were carried out. In Experiment 1, the specimen quality was assessed. Then the samples were pooled. The pooled specimens were allocated into 12 groups, in a 3 × 4 factorial design, including four levels of n-3 FA (0, 0.1, 1, 10 ng.mL ^-1) and three levels of α-tocopherol (0. 0.1, 0.2 mM). Then sperm critical characteristics such as proportion of motile sperm, progressive motile sperm, viable and abnormal sperms were measured. Furthermore, after freezing-thawing procedure, the recovery rate was considered as a vital indicator of semen quality. After thawing, the highest progressive motility was obtained when treated with 0.1 mM α-tocopherol and 1 ng.mL ^-1 n-3 FA. So, the second experiment was designed to measure the content of FA in specimens that fortified with 0.1 mM α-tocopherol, 1 ng.mL ^-1n-3 FA and also in groups without α-tocopherol and FA. Results: The data showed that before freezing, docosahexaenoic acid (DHA) level of sperm was increased when the FA introduced into extender (P ≤ 0.01). On the other hand, in the FA group, the n-3 FA and polyunsaturated fatty acid content were significantly higher compared with n-6 FA and saturated fatty acid level. However, in other groups, there were no significant alteration in the overall proportion of n-3 FA and n-6 FA were recorded (P ≤ 0.01). Conclusion: It was concluded that the cryosurvival of ram semen could be improved by adding DHA along with alfa-tocopherol as an antioxidant.