Effects of long-term liquid commercial semen extender and storage time on the membrane quality of boar semen

The objective of this study was to assess the sperm membrane integrity in extended boar semen during storage time using specific spectrum laboratory methods. Boar semen was diluted with the long-term liquid commercial extenders Androhep (A), Androstar (AS), Androstar plus (AS+), LD and M III and was stored up to 96 h. The sperm membrane integrity was evaluated by motility, viable spermatozoa, short hypoosmotic swelling test (sHOST) and by the activity of the enzyme aspartate aminotransferase (AST). Negative changes in the quality of sperm membrane in relation to storage time were observed after 48 h for sHOST, after 72 h for viable spermatozoa and after 72 h for motility. The percentage of viable spermatozoa was decreased by 0.27% each hour. A statistically significant difference between extenders A and LD was observed in sHOST after 72 h and 96 h storage (P < 0.05). The AST activity did not show any statistically significant differences in extenders and in storage time. In overall assessment Androhep was the best of the tested extenders, followed by AS, AS+, M III and LD in terms of motility, viable spermatozoa and sHOST. The correlations among laboratory methods were highly significant (P < 0.001). In conclusion, the results documented that the sperm membrane integrity was statistically significantly affected by extenders and storage time (P < 0.001). Boar semen quality was the best in extender A. sHOST is a very sensitive and relatively simple method for the assessment of sperm membrane integrity in diluted semen.