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 25µg/ml) and P free (control ; C) up to a final concentration of 16×106 per straw. All specimens were equilibrated for a period of 4h rata temperature of 4°C ,following which they were filledin 0.25-ml French straws and frozen. Addition of P resulted in favourable tai llength incomparison 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 term so ftotal, progressive sperm motility and total abnormality in comparison with C (p>.05). Inconclusion, 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.