Adaptation of the Hypoosmotic Swelling Test to Evaluate Membrane Integrity of Boar Spermatozoa

The objective of this study was to establish the optimal conditions for hypoosmotic swelling (HOS) test to assess the functional integrity of the membranes of boar fresh or frozen/thawed spermatozoa. When pooled semen sample was incubated for 30 min at $37^{\circ}C$ with different test solution of varied osmolarity, the highest percentage of HOS positive spermatozoa was observed in a 150 mOsmol fructose/Na-citrate solution (33.6%). Incubation time did not affect significantly the score of HOS positive spermatozoa observed in a 150 mOsmol fructose/Na-citrate solution at $37^{\circ}C$, but the osmolarity affected the score of HOS positive spermatozoa under the same condition above. Fresh semen was significantly better than frozen/thawed semen in semen parameters evaluated such as motility, viability, membrane integrity and lipid peroxidation (p<005). In the relationships of sperm parameters, motility vs viability, motility vs membrane integrity and viability vs membrane integrity were positively correlated ($0.82{\sim}0.94$) but lipid peroxidation vs other estimated factors was negatively correlated ($- 0.90{\sim}- 0.98$). Among the evaluation methods, motility vs Viability, motility vs membrane integrity and lipid peroxidation vs other estimated factors were significantly correlated (p<0.05). These results of this. study indicate that the optimal condition of HOST in boar spermatozoa is a 150 mOsmol fructose/Na-citrate solution for 30 min incubation at $37^{\circ}C$ and HOST can substitute the examination of motility, viability and lipid peroxidation.