“Short Paper” Application of Gamma Irradiation to Increase the Motility and Viability of Bovine Sperm after Freezing and Thawing

This study was conducted to determine the suitable dose of gamma rays for increasing sperm motility and viability after thawing and to assess its effects on malondialdehyde concentration and the rate of sperm DNA strand breaks. Sperm samples in liquid nitrogen were irradiated at doses of zero, 0.1, 0.3, 0.5, 0.7 and 0.9 Gy. The sperm quality and quantity parameters were evaluated before and after irradiation using CASA system. Sperm morphology and viability were evaluated using Eosin-Nigrosin staining. Malondialdehyde concentration was determined based on thiobarbituric acid method and DNA strand breaks analyzed by Comet assay. Data were analyzed based on randomized complete block design by SAS Software. The results showed that irradiation influenced (P<0.05) on motility and viability of sperms. The semen malondialdehyde concentration had no significant differences among treatments (P>0.05). Based on the Comet assay result, DNA strand breaks parameters had no significant differences with the control group, except at dose of 0.9 Gy. The results of this study demonstrated that gamma irradiation at dose of 0.7 Gy could enhance the motility and viability of sperms after thawing without negative effect on semen and sperm quality.