Effect of antioxidants on preservation of motility,viability and acrosomalintegrity of equine spermatozoa during storage at 5 degrees C

Preservation of liquid semen at 5 degreesC is an important technique in the breeding management of horses. Oxidative damage to spermatozoa during stor age is a potential cause of the decline in motility and fertility during hy pothermic storage of liquid semen. The objective of this study was to evalu ate the use of water-soluble and lipid-soluble antioxidants to improve the maintenance of motility of equine spermatozoa at 5 degreesC during storage for 72 to 96 h. In Experiment 1, the effect of addition of catalase on the maintenance of motility, viability and acrosomal integrity was determined. Semen was collected, and these treatments were applied: catalase (0, 100 Or 200 U/mL) in nonfat, dried skim milk extender (NFDSM; with or without semi nal plasma) or 10% seminal plasma + NFDSM. Motility was determined by compu terized semen analysis (CASA) at 0, 24, 48 and 72 h. Viability and acrosoma l integrity were determined at 72 h of storage. There was no significant tr eatment effect on the maintenance of sperm motility during 72 h storage, In Experiment 2, the effect of adding lipid-soluble antioxidants on maintenan ce of motility was evaluated. Semen was diluted to a final concentration of 25 x 10(6) sperm/mL in NFDSM containing butylated hydroxytoluene (BHT; 2.0 , 1.0, or 0.5 mM), Vitamin E (4.0, 2.0, 1.0 mM), or Tempo (2.0, 1.0, or 0.5 mM). Although the addition of BHT significantly reduced (P<0.05) progressi ve motility during storage compared to the control, there were no positive treatment effects of either Vitamin E or Tempo on maintenance of motility. In Experiment 3, the effect of adding water-soluble antioxidants on mainten ance of motility was evaluated. Semen was diluted in NFDSM containing these treatments: Trolox (2.0 mM), Tempo (1.0 mM), Vitamin C (0.45 mg/mL), BSA ( 3% w/v), combinations of these antioxidants, or control. Adding these water -soluble antioxidants did not significantly improve the maintenance of moti lity during cooled storage at 5<degrees>C. In conclusion, adding the enzyme scavenger, catalase, or a variety of lipid- and water-soluble antioxidants did not significantly improve the maintenance of motility during liquid se men storage at 5 degreesC. (C) 2001 by Elsevier Science Inc.