The effect of cysteine and superoxide dismutase on the quality of post-thawed chicken sperm

Abstract

The study was conducted to determine the influence of N-acetyl-l-cysteine (NAC) and superoxide dismutase (SOD) on chicken sperm motility, plasma membrane and acrosome integrity, mitochondrial activity, lipid peroxidation (LPO) and apoptotic changes after freezing-thawing process. Semen samples from fifteen Greenlegged Partridge roosters were pooled, diluted with EK extender without antioxidants (control), or supplemented with 5 mM NAC, or 200 U/mL SOD. Samples were subjected to cryopreservation. After thawing, sperm parameters evaluated by using CASA system and flow cytometry were assessed. The extender supplemented with NAC and SOD caused the increase (P < 0.01) in sperm motility and provided the higher percentage of rapid sperm (P < 0.01) compared to control. The addition of NAC increased the progressive motility of cells (P < 0.01). In NAC and SOD groups post-thaw plasma membrane integrity was higher (P < 0.05) and less spermatozoa showed apoptotic changes (P < 0.01, P < 0.05). Post-thaw percentage of sperm with high mitochondrial activity was the greatest (P < 0.05) with NAC addition. The SOD supplementation only reduced (P < 0.05) the percentage of sperm with LPO, following the cryopreservation. These results indicate that the addition of NAC (5 mM) and SOD (200 U/mL) is beneficial for the function of frozen-thawed chicken spermatozoa. The antioxidants prevented the reduction in motility, viability and mitochondrial membrane potential, as well as protected from apoptotic changes in sperm. Lipid peroxidation in sperm plasma membrane was decreased by SOD supplementation. Therefore, these antioxidants can be recommended as an additional component of chicken freezing extender.

Keywords: Antioxidants; Avian semen; Cryopreservation; Cysteine; Superoxide dismutase.