Abstract
The current study evaluated the physiochemical quality and gene expression profile of post‐thawed buck semen after supplementation with antioxidants [melatonin (M), L‐carnitine (LC), cysteine (Cys), LC + M, M + Cys, LC + Cys, LC + Cys + M] in comparison with the non‐treated control group. Physical and biochemical characteristics of semen were evaluated following freezing and thawing. Transcript abundance of six selected candidate genes was profile using quantitative real‐time PCR. The data demonstrated significant enhancement of post‐freezing total motility, progressive motility, percentage of live sperm, CASA parameters, plasma membrane and acrosome integrity in all groups supplemented with Cys, LC, M + Cys and LC + Cys compared with the control group. The biochemical analysis of semen indicated that semen groups supplemented with LC and LC + Cys recorded increased levels of GPX and SOD that were coupled with up‐regulation of antioxidant genes (SOD1, GPX1 and NRF2) and mitochondrial transcripts (CPT2 and ATP5F1A). Moreover, H2O2 level and DNA fragmentation percentage were reduced compared with other groups. In conclusion, supplementation of Cys alone or in combination with LC positively improved the post‐thaw physiochemical properties of rabbit semen through activation of bioenergetics‐related mitochondrial genes and cellular antioxidant defence mechanism.