The cryoprotective effect of iodixanol in buffalo semen cryopreservation

This is the first report to examine the effect of iodixanol (OptiPrep^TM) on cryosurvival of buffalo spermatozoa. A total of thirty ejaculates (five ejaculates from each bull) from six buffalo bulls were used for this experiment. Each ejaculate was divided into four aliquots and diluted in freezing extender supplemented with different concentrations of OptiPrep^TM (0, 1.25, 2.5 and 5%) and then cryopreserved. The semen quality variables were evaluated before and after freezing of the semen. There were no effects of OptiPrep^TM (P>0.05) on sperm kinetics, motility, abnormality and membrane integrity of fresh extended spermatozoa. However, after freeze-thaw, sperm motility, plasma membrane integrity and distance travelled in cervical mucus of 2.5% OptiPrep^TM treated samples showed significantly higher (P<0.05) compared to other treated and control samples. No significant differences (P>0.05) were seen in sperm abnormality and acrosomal integrity of treated and control frozen-thawed samples. The total antioxidant capacity of 2.5 and 5% OptiPrep^TM treated frozen-thawed sperm were found to be higher (P<0.05) as compared to other groups; whereas the MDA level in OptiPrep^TM treated sperm was significantly lower than the control (P<0.05). In incubation test, 2.5% OptiPrep^TM proved to be better in preservation of sperm motility as compared to other treated and control samples. In conclusion, the present study has shown that iodixanol has the ability protect spermatozoa against oxidative stress and resulting overall improvement in the post-thaw semen quality.