Addition of reduced glutathione to diluent of lamb semen during storage (5 °C)
The objectives were: first, determine a recommended concentration of GSH to be used during cooling of sheep semen to 5°C; and second, evaluate the effects of GSH on the acrosome integrity and sperm capacitation. Experiment 1, 12 ejaculates from two Pelibuey rams were used. Each ejaculate was divided into four aliquots corresponding to the GSH concentrations tested (0.0, 0.5, 1.0 and 5 mM). Aliquots were stored under refrigeration (5°C) for 24 h. Live sperm motility was evaluated at 0, 1, 2 and 24 h of storage and at 24 h after warming to 37°C (reactivation). Experiment 2, 22 ejaculates were evaluated by the technique of chlortetracycline sperm capacitation after 24 h storage at 5°C.. At 0, 1, and 2 h of storage there were no significant differences between sperm motilities using different concentrations of GSH. At 24 h, 5 mM GSH showed the highest sperm motility (29.22%). This concentration also had the highest percentage of motility during reactivation (80.29%) and live sperm concentration, 81.44% (p <0.05). The percentage of non-capacitated and acrosome intact sperm increased to 42% when 5 mM GSH (p <0.05) was used. It is concluded that the antioxidant and protective activity of GSH during cooling is dependent on concentration and storage time.