Supplementation of soybean lecithin-based cryopreservation medium with glutathione: Fertility and flow cytometry study of ram frozen-thawed semen

Abstract

Abstract This study was aimed to evaluate the beneficial effects of reduced glutathione antioxidant in soybean lecithin-based cryopreservation medium on fertility and quality parameters of ram semen. In experiment 1, semen samples were collected from five rams and diluted in the freezing extender contained various concentrations of glutathione as follows: extender without glutathione (G0), extender containing 0.5 mM (G0.5), 1 mM (G1), 2 mM (G2), 4 mM (G4) and 8 mM (G8) glutathione. Motility, membrane functionality, morphology, mitochondrial activity, acrosome integrity, viability, apoptosis status, lipid peroxidation, DNA fragmentation and reactive oxygen species (ROS) concentration were assessed after thawing. In experiment 2, pregnancy, parturition, lambing and twining rates were evaluated after artificial insemination with frozen-thawed semen. In results, G4 showed higher (P ≤ 0.05) total and progressive motility, membrane functionality, acrosome integrity, and lower (P ≤ 0.05) lipid peroxidation and ROS concentration compared to the other groups. Mitochondrial activity and viability were higher (P ≤ 0.05) and late apoptotic-like changes were lower (P ≤ 0.05) in G2 and G4 compared to the other groups. DNA fragmentation and late apoptotic-like changes were higher (P ≤ 0.05) in G8 compared to the other groups. No significant difference was observed among groups in cases of morphology and reproductive performance. In conclusion, supplementation of cryopreservation medium with 4 mM reduced glutathione improves the quality parameters of ram spermatozoa but it was not reflected to the reproductive performance.