RESUMO
BACKGROUND: Many studies have been shown that freezing induced oxidative stress has detrimental effect on post-thaw sperm quality. OBJECTIVE: This study was conducted to investigate the effect of tert-butyl hydroquinone (tBHQ) on bull semen crtopreservation. MATERIALS AND METHODS: In this study, four different levels of tBHQ [Optidyl containing zero (T0), 2.5 (T2.5), 5 (T5), and 7.5 µM (T7.5) tBHQ] was used to study the effect of tBHQ on freezability of bull semen. On each collection day, four ejaculates were collected (a total of 24 ejaculates from four bulls), pooled and divided to four equal parts. Each part was diluted with one of the above-mentioned extenders and frozen. After thawing, sperm motility, plasma membrane functionality and integrity, apoptosis status and mitochondrial activity were assessed. RESULTS: The results show that total sperm motility was significantly higher in T5 compared to other groups. The value of VSL was significantly lower in T5 compared to T0. Also, T5 resulted in lower LIN and STR versus T0 and T2.5 groups. All extenders containing tBHQ resulted in a significantly higher percentage of sperm with functional membrane compared to T0 groups. Finally, Apoptosis related parameters and mitochondrial activity were not significantly difference between the groups. CONCLUSION: adding 5 µM tBHQ to the bull semen extender can be beneficial for post-thaw sperm quality. Also, in vivo or in vitro fertility test is recommended to test fertilizing ability of tBHQ exposed sperm.