Optimizing Bull Semen Cryopreservation Media Using Multivariate Statistics Approaches

Quality and redox state of bovine sperm cryopreserved with resveratrol use of resveratrol in bovine semen

The use of antioxidants for semen preservation prevents oxidative damage caused by reactive oxygen species (ROS). One of the most promising natural antioxidants is resveratrol, a phytoalexin derived from plants, grapes, berries, peanuts and red wine. To evaluate the effect of resveratrol on the quality and redox status of cryopreserved bovine semen. Five bulls were subjected to electroejaculation to obtain 15 ejaculates. Each ejaculate was extended with a tris-egg yolk-glycerol-based medium and divided into six aliquots supplemented with 0 (control), 10, 20, 30, 40 and 50 μM of resveratrol. Semen was frozen with liquid nitrogen vapours. Post-thawing, motility and kinetics were evaluated using a computer-assisted sperm analysis (CASA) system, membrane integrity using the hypoosmotic test (HOST), morphology by staining with eosin-nigrosin, sperm vitality by fluorescence microscopy with the SYBR14/IP probes. Total antioxidant capacity (TAC) was evaluated using the ABTS•+ assay and ROS was evaluated using spectrofluorimetry with the H2 DCFDA probe. For the statistical analysis linear models were adjusted and means were compared using the Tukey test. All concentrations of resveratrol reduced post-thawed motility and kinetics of sperm. Supplementation with 40 and 50 μM of resveratrol reduced sperm kinetics, and between 30 and 50 μM of resveratrol alterations in the sperm membrane and morphology were observed. However, using resveratrol at 50 μM increased TAC and at 20 μM, it reduced ROS production of cryopreserved bovine semen. Resveratrol appears to have a dose-dependent effect in which higher doses produce greater sperm alterations, however, it can increase semen TAC during freezing. It is concluded that resveratrol can increase antioxidant capacity and reduce ROS production in cryopreserved bovine semen. However, its use between 10 and 50 μM reduces post-thawing semen quality.