Antioxidant Potential of Ferulic Acid on the Freezability of Bull Semen

Ejaculates were collected twice a week from the bulls, via an artificial vagina, during two weeks. The suitable ejaculates obtained for sperm density (≥ 1.4 × 109 spermatozoa / ml) and for motility (≥ 75%) were used for dilution and freezing of semen. A Tris-based extender (Tris 297.58mM, citric acid 96.32mM, fructose 82.66mM, egg yolk 15% (v/v), glycerol 5% (v/v), gentamicin 0.1 ml / 100ml, pH 6.8-7.0) was used as the base extender (cryopreservation diluent). Pooled ejaculate was split into 2 equal aliquots and diluted at 32 °C with base extender containing ferulic acid (100 μM) and no antioxidant (control), respectively. Each aliquot was diluted to a final semen concentration of approximately 1.2×108 sperm/ml (single step dilution), in 15-ml polypropylene centrifuge tubes. After dilution, semen samples were kept at room temperature for 10 minutes then, the diluted semen samples were aspirated into 0.25 ml French straws, sealed with polyvinyl alcohol powder and equilibrated at 5 °C for 3 h. After equilibration, the straws were frozen in liquid nitrogen vapour (4 cm above the liquid nitrogen, ~-100oC) for 10 min and then plunged into liquid nitrogen for storage, -196oC. In the study, sperm samples containing antioxidant and non-antioxidant were evaluated for spermatozoa motility and membrane integrity after freezing / thawing. In the present study, no statistically significant difference was found between the control and experimental groups for motility and membrane integrity after freeze-thawing. The application consisted of 4 replications.