RESUMO
Supplementation of cooling medium with some antioxidants could be a helpful way to improve sperm quality during chilling process. The current study was aimed to assess the influence of using Mito-TEMPO in cooling medium on quality parameters and reproductive performance of sheep semen during chilling process. In this study, diluted semen samples were assigned into 5 parts, and received 0, 0.5, 5, 50 and 500 µM Mito-TEMPO. The prepared samples were stored at 5 °C up to 48 h. Chilled sperm motility, viability, abnormal morphology, mitochondrial membrane potential, membrane functionality and malondialdehyde concentration were assessed during 0, 24 and 48 h. For evaluation of reproductive performance, artificial insemination was performed via 24 h-chilled semen. In results, at time 0, no difference was observed among groups. Using 5 and 50 µM Mito-TEMPO resulted in higher (P ≤ 0.05) cooled sperm total motility, progressive motility, membrane functionality, viability and lower malondialdehyde concentration than the other groups during 24 and 48 h storage. The rate of mitochondrial membrane potential was greater (P ≤ 0.05) in treated groups with 5, 50 and 500 µM Mito-TEMPO. Pregnancy, parturition and lambing rates were higher (P ≤ 0.05) when ewes were inseminated with 24 h-chilled semen samples containing 5 and 50 µM Mito-TEMPO compared to the control group. Therefore, supplementation of cooling medium with Mito-TEMPO (5 and 50 µM) could be an efficient method to improve the quality and reproductive efficiency of ram's cooled semen during storage period.