Addition of vitamin c extender and post-cryopreservation semen quality in bulls

Abstract Text: The process of spermatozoa freezing provides a resting state of cell while preserving cellular structure and fertilizing capacity of sperm. However, after thawing, semen quality is reduced compared to fresh semen. Sperm cell is able to generate and degrade reactive oxygen species (ROS) necessary for cell functioning, and oxidative stress is a cellular damage caused by imbalance between increased ROS and decreased antioxidant mechanisms. During cryopreservation can occur an increase in oxidative stress due deficiency of intra and extra cellular antioxidant defense system. Vitamin C is considered a great antioxidant of extracellular fluid, working mainly preventing formation of lipid hydroperoxide in plasma lipoproteins and protecting phospholipids in cell membranes. Thus, this study aimed to evaluate the use of vitamin C in cryopreservation extender medium of bull semen to reduce damage caused by cryopreservation process. 16 Brangus bulls in reproductive age were used. Ejaculate was collected by electrostimulation. After analyzed, samples were diluted in a extender (TRIS-citrate-egg-yolk with 4% of glycerol), divided into two treatments: the control group (without additive, CG) and other group supplemented with vitamin C (0.45 mg/mL, GS). Thawing was performed in water bath at 37°C for 30 seconds. After that aliquots were evaluated to: sperm motility, sperm vigor, sperm viability and sperm membrane integrity. Data were analyzed by analysis of variance with a significance level of 5%. Vitamin C did not improved sperm motility after cryopreservation (P>0.005, CG 45.06 ± 5.51 vs SG 43.18 ± 4.04). Sperm vigor on GC (0.93 ± 0.85) not differ (P>0.05) of SG (1.00 ± 0.89). Sperm viability in GC (51.71 ± 9.70) was not different (P>0.05) to SG (49.99 ± 6.46). Sperm membrane integrity was not affected by supplementation (P>0.05). Medium supplementation with vitamin C did not affect seminal parameters evaluated, demonstrating that supplementation was not effective in reducing damage caused by cryopreservation in bovine semen. Keywords: antioxidant; sperm viability; oxidative stress.