Effect of butylated hydroxytoluene on dog sperm longevity in chilling storage and cryopreservation

This study evaluated the effect of butylated hydroxytoluene (BHT), a lipid-soluble antioxidant, on dog sperm in chilling storage and cryopreservation. In Experiment 1, 0.2, 0.4, 0.8 and 1.6 mM BHT were added to egg yolk Tris extender (EYT), and sperm were stored at 4°C for 96 hr. Sperm motility, viability, acrosomal integrity and morphological abnormality in the BHT treatment groups were not different from those of the control (0 mM BHT). In Experiment 2, the effect of BHT in EYT containing 0.75% Equex STM paste and 5% glycerol on survivability of cryopreserved sperm was examined after culture at 39°C for 3 hr. Sperm motility, viability and acrosomal integrity in the 0.2 to 0.8 mM BHT treatment groups were not different from those of the control. However, sperm motility, viability and acrosomal integrity decreased when 1.6 mM BHT was added to the extender (P<0.05). In conclusion, supplementation of the extender with 0.2 to 0.8 mM BHT did not affect characteristics of dog sperm in chilling storage and cryopreservation. Supplementation of 1.6 mM BHT did not affect characteristics of chilled sperm but impaired longevity of cryopreserved sperm in the dog.