Select antioxidants improve the function of extended boar semen stored at 10°C

The objective was to determine the effects of antioxidant addition to extender on viability, acrosome integrity and penetrability in vitro of boar spermatozoa preserved at 10°C. Washed spermatozoa were resuspended at 1 × 10⁸ cells/mL in modified Modena solution containing 20% (v/v) boar seminal plasma and 5 mM antioxidant (glutathione, cysteine or hypotaurine). Control aliquots were the same suspension without added antioxidants. Sperm suspensions were then chilled to 10°C with a computerized cooling program. Sperm viability after 7 and 14 d was higher in the presence of glutathione or cysteine, whereas hypotaurine did not improve the survival rate. Percentage of chlortetracycline (CTC) fluorescence pattern as intact live cells was higher in spermatozoa preserved with glutathione or cysteine at 7 and 14 d of preservation. When the preservation period was prolonged until 57 d, survival rate was higher with cysteine than controls. When spermatozoa were preserved with cysteine and then inseminated in an IVF system, penetration rate was not different until 15 d of preservation and higher than controls at 15-29 d, whereas no sows became pregnant after AI with spermatozoa preserved for 21-23 d. Therefore, glutathione and cysteine can improve the viability and functional status of boar spermatozoa during liquid preservation and boar spermatozoa penetrated in vitro even after preservation in the presence of cysteine at 10°C for 29 d.