Survival to freezing of sperm collected by vas deferens from Vicugna pacos with tempol antioxidant addition

Abstract

Background: The viscosity of semen alpaca and oxidative stress are some of the difficulties of cryopreservation. Is continuous, the search of methods to reduce and even avoid this viscosity, as well as decrease the effect of oxidative stress of the alpaca semen. The purpose of the study was to determine the effect of the adding of tempol antioxidant on spermatozoa of epididymal alpaca obtained by desviation of vas deferens. Methodology: The vas deferens from three alpacas with adequate sperm parameters were deviated surgically. Sperm samples were collected three times a week and were mixed to annul the individual effect. Collective sample was divided into four aliquots and it was placed in a refrigerator up to 5°C for 2 h. Vitality and membrane integrity sperm were evaluated immediately harvested, cooled and post freezing/thawing. When the temperature reached 10°C in cooling phase was added tempol antioxidant at a final concentration of 0.0, 0.5, 1.0 and 1.5 mM. These were packaged in 0.25 mL straws and placed on liquid nitrogen vapors during 6 min and then submerged. Results: The initial sperm vitality was 79.30%, after cooling 66.68, 75.15, 70.03 and 55.03% and post freeze/thawing 42.45, 47.96, 32.06 and 26.13%. The initial sperm membrane integrity was 75.69%, after cooling 63.33, 66.14, 57.56 and 51.83% and 36.26, 44.20, 34.43 and 27.94% post freezing/thawing. In all cases, there was statistical difference (p ≤ 0.05). Conclusion: The sperm collection technique by vas deferens from alpaca and low concentrations of tempol antioxidant (0.5 mM) improves the sperm vitality and the functional sperm membrane integrity.