Effect of supplementation of lecithin nanoparticles-based extender with reduced glutathione on freezability of bull sperm

This study was designed to add the reduced glutathione to a lecithin nanoparticle-based extender and evaluate the quality of bull sperm after freezingand thawing. In the present study, the effect of four different levels of glutathione (0, 1, 2.5 and 5 mM) in extender-based on lecithin nanoparticles wasevaluated. The lecithin nanoparticles were prepared and the particle size was reduced by using a sonicator device. During three weeks, 48 ejaculatesfrom six Holstein bulls were collected and frozen. Properties evaluated after freezing and thawing were kinetic parameters (CASA), membraneactivity (HOST), membrane integrity (eosin-nigrosine) and morphology (Hancock solution). The results showed that using 2.5 mM glutathione in theextender significantly increased total and progressive motility (63.38±1.5 and 43.1±1.1 respectively, P <0.05). The results of eosin-nigrosine stainingand Host test showed that the highest viability and cell membrane functionality were related to 2.5 mM treatment (64.8±1.5 and 58.1±1.1 respectively)(P<0.05). In general, 2.5 mM glutathione could improve the quality of bull sperm compared with other concentrations after freezing and thawingprocess. It seems that the 2.5 mM glutathione is optimum concentration for bull extender based on the lecithin nanoparticles.