Folw cytometric evaluation of frozen-thawed bull semen in a semen extender containing ethanol

The aim of the present study was to investigate the effect of ethanol on bull sperm quality after freeze thawing process. Treatments used in this study included: 1) semen extender without ethanol as control group (C) and 2) semen extender containing 0.25% ethanol (E). A total of 24 ejaculations were collected from four healthy mature Holstein bulls in 3 consecutive weeks and twice a week. In each replicate, semen samples were mixed to eliminate individual differences and then divided into two equal parts and each of them were extended with one of the aforementioned extenders. Afterward the treatments were frozen using a standard protocol. After thawing, sperm motion characteristics, plasma membrane integrity and functionality, apoptosis status and mitochondrial activity were assessed. The result of this study was showed that spermatozoa in control group had higher total motility (68.5±1.96 vs 76.17±2.49) and lower apoptosis (10.65±0.36 vs 13.13±0.33) in comparison with group treated with ethanol (p≤0.05). Also, no differences were observed in plasma membrane integrity and functionality and mitochondrial activity between two treatments (p≥0.05). In conclusion, the results showed that ethanol could negatively affect post thaw characteristics of bull spermatozoa.