Positive effect of butylated hydroxytoluene (BHT) on the quality of cryopreserved cat spermatozoa.

The semen cryopreservation processes are associated with state of oxidative stress induced by high levels of reactive oxygen species (ROS), causing damage to functional spermatozoa. Whereby, antioxidants have been utilized to scavenge or neutralize the elevated levels of ROS. The aim of at the present study was to evaluate the effect of adding BHT to the freezing extenders on post-thaw characteristics of domestic cat spermatozoa. Semen samples were frozen in Tris-fructose-citric acid-based extender, supplemented with different concentrations of BHT (0.5 mM, 1.0 mM and 2.0 mM) and a control sample without antioxidant. After thawing, sperm samples were assessed for motility by computer-assisted sperm analysis and viability, acrosome integrity, superoxide anion production and membrane lipid peroxidation status by flow cytometry. In the study, the parameters of sperm motility and acrosome integrity were significantly higher in 2.0 mM BHT compared to sperm frozen in the extender with other concentrations and control (P < 0.05), in addition, this concentration reduced significantly the superoxide anion production and lipid peroxidation of the sperm. The results demonstrated that the supplementation of BHT to the freezing extender could protect the function and cellular structure of domestic cat sperm from cryoinjuries.