RESUMEN
This study aimed to investigate the effectiveness of using red pine bark tree extract (P; Pinus brutia Ten) as a TRIS extender in an attempt to prevent oxidative stress in bull spermatozoa after freezing. Semen specimens were obtained from Simmental bulls via an artificial vagina and pooled. They were separated into five specimens and diluted with Tris extender consisting of P (200, 100, 50 and 25 µg/ml) and P free (control; C) up to a final concentration of 16 × 106 per straw. All specimens were equilibrated for a period of 4 hr at a temperature of 4°C, following which they were filled in 0.25-ml French straws and frozen. Addition of P resulted in favourable tail length in comparison with C (p < .05). The lowest malondialdehyde levels and the highest glutathione levels were detected in all P groups (p < .05). Supplementation with P did not show advanced results in terms of total, progressive sperm motility and total abnormality in comparison with C (p > .05). In conclusion, it has been shown that although P added to a Tris extender does not have a positive effect on sperm motility, it prevents chromatin damage by reducing oxidative stress, in addition to reducing head abnormalities when used at the amount of 50 µg/ml.