Docosahexaenoic acid and alpha-tocopherol improve sperm cryosurvival in goat

Abstract

The aim of this study was to investigate the effect of adding a polyunsaturated fatty acid source (n-3 fatty acids), accompanied by alpha-tocopherol, to extender on freezing ability and fatty acid (FA) composition of goat sperm. Mahabadi bucks were used in this research. In first experiment, the pooled semen was divided into 12 groups, in a 3×4 factorial design including four levels of n-3 FA (0, 0.1, 1 and 10 ng ml-1) and three levels of vitamin E (VE) (0, 0.1 and 0.2 mmol). The percentage of motility, progressive motility and viability of semen were evaluated. The treatment of 0.2 mmol VE and 10 ng ml-1 n-3 FA had the best semen quality in comparison to the control and the other treated groups, after thawing. The second trial was conducted to determine fatty acid content of sperm after the treatment with 0.2 mmol VE and 10 ng ml-1 n-3 FA and the treatment without VE and FA. Adding FA to the extender led to an increase in Docosahexaenoic acid (n-3) level before freezing (P≤0.01). The overall proportion of n-3 FA to n-6 FA was significantly higher in the FA group than in the other group (P≤0.01) before freezing, and the ratio of polyunsaturated fatty acids (PUFA) to saturated fatty acids (SFA) was higher (P≤0.05) in the FA group before freezing than that after thawing. Results suggest that the addition of n-3 FA with an antioxidant could improve freezing ability of goat semen via changing the lipid composition of sperm cell.