Ergothioneine attenuates the DNA damage of post-thawed Merino ram sperm

The objective of the current study was to evaluate the effects of antioxidant ergothioneine added to cryopreservation extender on the DNA integrity of Merino ram sperm. Semen samples from 5 mature Merino rams (1 and 2 years of age) were used in the study. Semen samples, which were diluted with a Tris-based extender containing ergothioneine at different concentrations and no antioxidant (control), were cooled to 5 ◦C and frozen in 0.25 ml French straws. Frozen straws were then thawed at 37 ◦C for 20 s in a water bath for evaluation of sperm DNA damage using the Comet test. The addition of ergothioneine at concentrations of 1, 2 and 4 mM resulted in lower sperm with damaged DNA (5.4, 4.7 and 3.2%, respectively) than that of control (7.9%), thus reducing the DNA damage (P < 0.01). Findings of this study showed that the increasing concentrations of ergothioneine in semen extenders, were of greater benefit to DNA integrity of frozen-thawed ram sperm.