Broiler chickens fed diets supplemented with 0.25, 0.75, and 1.00% of POP had a lower (Po0.05) feed conversion ratio (FCR) compared to control at days 11– 25 and 1–43 of age. At day 43 of age liver superoxide dismutase (SOD) and glutathione peroxidase (GSHPx) activities were not affected by the treatments, whereas a greater (Po0.05) liver catalase activity (CAT) was recorded in broiler chickens fed 0.25 or 0.75% POP