![]() Several studies have shown that cauda epididymal sperm are of acceptable quality and a high level of maturation, being able to achieve fertilisation and successful pregnancy after their use for insemination (Goodrowe and Hay, 1993, Lengwinat and Blottner, 1994, Tsutsui et al., 2003, Soler et al., 2005, Toyonaga et al., 2011). Post-mortem epididymal sperm collection from the cauda epididymis is a useful tool for male germplasm and genetic resource banking in wild animals (Foote, 2000). These findings indicate that green tea polyphenols and α-tocopherol have protective effects on the preservation of sperm characteristics and IZUMO1 protein integrity of cat epididymal sperm during long-term chilling. Sperm IZUMO1 protein was markedly conserved by supplementation of 5 µg/ml α-tocopherol together with 0.75 mg/ml green tea polyphenols up to 12 days in cold storage. Without antioxidant, cold storage can gradually degrade the IZUMO1 protein level. Cat IZUMO1 proteins, 17 kDa, were identified at the equatorial segment of acrosome reacted sperm. Using α-tocopherol at 5 µg/ml together with 0.75 mg/ml green tea polyphenols in the semen extender is the most suitable condition to retain the sperm characteristics up to nine days of preservation. Sperm characteristics and IZUMO1 protein expression were investigated before and after chilling at 3, 6, 9, 12 and 15 days. One sample without antioxidants served as a control. Sperm samples were collected from the cat epididymis before being diluted with semen extender containing various concentrations of α-tocopherol (0, 2.5, 5 and 7.5 µg/ml) and 0.75 mg/ml green tea polyphenols and cooled to 4 ☌. The purpose of this study was to investigate whether supplementation of chilled semen extender with green tea polyphenols together with α-tocopherol would provide synergistic effects to prolong sperm survival and maintain IZUMO1 protein stability in cat spermatozoa.
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