Effect of glutathione in soybean lecithin-based semen extender on goat semen quality after freeze-thawing

This study was conducted to investigate the effect of glutathione in a soybean lecithin-based semen extender on post-thawed goat semen quality. A total of 20 ejaculates were collected from four Mahabadi goats and diluted with four extenders: (1) egg yolk tris-based extender (EYT), (2) soybean lecithin-based extender (SL0), (3) soybean lecithin-based extender containing 5 mM glutathione (SL5), and (4) soybean lecithin-based extender containing 10 mM glutathione (SL10) and the experiment was replicated for five times. Sperm motility and motion parameters, the percent of normal sperm, plasma membrane integrity, viability, and the levels of malondialdehyde (MDA) were determined after freeze-thawing. Glutathione at the level of 10 mM provided the lowest percent of total and progressively motile sperm (45 ± 2.94, 25.8 ± 1.81). The percent of plasma membrane intact sperm was lower in SL5 (55.44 ± 2.4) and SL10 (51.52 ± 2.4) than that of EYT (64.27 ± 2.4) and SL0 (62.93 ± 2.4). Sperm viability was significantly decreased in SL10 (57.98 ± 2.27) in comparison with EYT (66.89 ± 2.27). The percent of normal sperm was not significantly different between groups. Also, the MDA level was lower in SL5 (1.61 ± 0.29) than that of other groups. The results of this study showed that most of the post-thawed sperm quality parameters were not significantly different between EYT and SL0. Moreover, addition of 5 and 10 mM glutathione in a soybean lecithin-based extender could not improve goat sperm quality after freezethawing. In conclusion, it seems that soybean lecithin-based extender can be a suitable replacement for egg yolk tris-based extender, but addition of glutathione at 5 and 10 mM cannot fortify the soybean lecithin-based extender for goat semen cryopreservation.