Supplementation of antioxidant BHT to different bull semen extenders enhances semen quality after chilling

The effects of adding various concentrations of antioxidant,butylated hydroxytoluene (bht) on chilled bull semen for 72 h at 4°c in bioxcell® (bx),tris egg-yolk-(tey) and citrate egg-yolk-(cey) based semen extenders were studied. twenty-two ejaculates collected from three bulls,each extended using three extenders with bht at 0 (control),0.5,1.0,1.5,2.0 and 3.0 mm/ml,were evaluated for sperm quality parameters. extended semen was packaged into 0.25 ml straws containing 20 x 106 spermatozoa and chilled for 72 h. four random straws each from the control and treatment groups were warmed at 37°c,pooled and evaluated using a computer-assisted semen analyser (ivos hamilton thorne biosciences) for general and progressive motilities,and for morphology,viability and acrosome damage using eosin-nigrosin stain under phase-contrast microscope. results showed that sperm morphology,viability and protection of acrosome damage were signifcantly improved (p<0.05) at bht concentrations of 0.5 in bx and 1.0 mm/ml in tey and cey compared to the controls. the bht also showed a potential positive effect on progressive motility at 0.5 mm/ml in bx and 1.0 mm/ml in tey and cey. high concentrations of bht (2.0 and 3.0 mm/ml),however,produced deteriorative effects on the sperm parameters in all the extenders. in conclusion,bht when added at 0.5 mm/ml in bx and 1.0 mm/ml concentration to tey and cey extenders improved the quality parameters of bull chilled semen. © universiti putra malaysia press.