The effect of vitamin E, green tea extracts and catechin on the in vitro storage of turkey spermatozoa at room temperature

Turkey semen has to be stored under aerobic conditions. The spermatozoan phospholipid content of avian and mammalian species are characterised by high levels of long-chain polyunsaturated fatty acids. It has been reported that peroxidation of the polyunsaturated lipids in spermatozoa results in loss of motility and membrane integrity and therefore lower fertilising capacity. The effects of lipid- (vitamin E) and water- soluble antioxidants (green tea extracts and catechin) added to a standard diluent were assessed during in vitro storage of turkey spermatozoa at room temperature. Semen was collected from 15 male turkey breeders and pooled. The sperm quality parameters measured were the motility index and the proportion of damaged spermatozoa during in vitro incubation for up to 48 hours. Vitamin E (1000 ppm) significantly lowered the proportion of damaged spermatozoa after 6, 24 and 48 hours of storage at room temperature. The motility index was significantly higher in the vitamin E treatment after 6 hours of storage. Catechin and green tea extracts (100 ppm) significantly increased the proportion of intact spermatozoa after 48 hours of incubation but had no effect on the motility index. The vitamin E treatment resulted in a significantly lower proportion of damaged spermatozoa compared to that of catechin and green tea extract treatments after 48 hours of incubation. Furthermore the fatty acid and phospholipid class profiles of turkey spermatozoa, before and after induced peroxidation, were determined in control and vitamin E supplemented diluents. The proportions of n-6 long chain polyunsaturated fatty acids (PUFA, mainly 20:4 and 22:4), phosphatidyl ethanolamine (PE) and phosphatidyl serine (PS) decreased after 1 hour of incubation in the presence of Fe2+ at 37°C. Vitamin E (200 ppm) prevented the loss of PUFA, PE and PS during induced peroxidation. We suggest that the inclusion of vitamin E into the diluent protects the integrity of spermatozoan membrane lipids during in vitro storage.