Butylated hydroxytoluene (BHT) improved semen quality and sperm DNA of frozen-thawed Arabian stallions preserved in modified INRA-82 extender

Abstract

Background

Alpha-tocopherol is one of the non-enzymatic lipophilic antioxidants. Butylated hydroxytoluene (BHT) is a synthetic analog with similar modes of action in protecting the cryopreserved sperms.

Aims/objectives

This study hypothesized that a certain concentration of any antioxidant is suitable for improving the post-thaw semen quality of stallions.

Methods

To determine the optimum BHT concentration, a synthetic antioxidant similar to vitamin E in potency and scavenging oxidative stress power in concentrations of 0.0, 0.25, 0.50, 1.0, 2.0, and 4.0 mM/ml were added to semen extender. The post-thaw sperm progressive motility at 0, 1 h, 2 h, and 3 h, the sperm viability index, the plasma membrane integrity tested by the hypo-osmotic swelling test (HOST), the acrosome integrity, non-fragmented DNA, % of DNA in the comet head, % of DNA in the comet tail, comet tail length, and comet tail moment were compared.

Results

According to our hypothesis, 1.0 mM BHT was the most suitable concentration that preserved the highest (P < 0.0001) post-thaw sperm progressive motility at 0.0, 1 h, 2 h, 3 h., the highest viability index (P < 0.0001), plasma membrane and acrosome integrities (P < 0.0001),non-fragmented DNA (P < 0.001), and % of DNA in the comet head (P < 0.001), the lowest DNA % in the comet tail (P < 0.001) and comet tail moment (P < 0.0001), and the shortest (P < 0.0001) comet tail length.

Conclusions

The concentrations of BHT around 1.0 mM/ml (0.5, 2.0mM/ml) proved better post-thaw semen characteristics, but increasing BHT concentrations from >2.0mM/ml to 4.0 mM/ml started to deteriorate semen quality than non-supplemented control. The optimum BHT concentration for modified INRA-82 is 1.0 mM/ml.