This study was conducted to investigate the effect of different levels of savory (Satureja hortensis) powder and its essential oil on performance and antioxidant status of broiler chickens under heat stress (34±2 ˚C for 8 hours per day). A total of 336 one-day-old male broiler chicks (Ross-308) were divided into 6 treatments and 4 replications (14 birds per replicate). Experimental diets were a corn-soybean based diet with no supplement (control), diet containing 200-ppm vitamin E as positive

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... ntrol, diets containing 1 and 2% of savory powder and diets containing 100 and 200 ppm of savory essential oil. Antioxidant status was measured by analysis of malondialdehyde (MDA), glutathione peroxidase (GPX) and super oxide dismutase (SOD) activities in liver tissue. Results indicated that body weight, weight gain, feed intake and feed conversion ratio were not significantly affected by the experimental treatments. Experimental diets except diet containing 1% savory powder, decreased (P<0.05) MDA concentrations and increased SOD activities (P<0.05) in liver tissue as compared to the control diet. However, there were no significant differences in liver GPX activities between treatments. The results of this study concluded that, supplementation of diet with savory powder and its essential oil improved antioxidant status in broiler chickens reared under heat stress and it can be considered as a replacement for synthetic antioxidant in poultry diet in heat stress conditions.