This experiment was conducted to evaluate the effects of two levels (3 and 5%) of local produced dried orange peel powder (DOP) with or without supplementation of exogenous xylanase enzyme (Xylanase-50000®) on zootechnical performance, immunity and antioxidant status of broiler chickens. Five hundred 1-day-old broiler chicks of both sexes were used in this investigation. Chicks were weighed and randomly divided into 5 dietary treatments. Each treatment was subdivided into four replicates containing 25 chicks/replicate in 20 floor pens. The first group consumed the basal corn/soybean meal diets without supplementation and served as control group. Treated groups A and B were reared on the reformulated basal diets
supplemented with 3% and 5% of dried orange peel powder (DOP) respectively. Groups C and D were fed on reformulated basal diets supplemented with 3% and 5% dried orange peel powder and fortified with 50 g Xylanase-50000®/ton feed. The control and treated experimental diets were formulated to be isocaloric and isonitrogenous. At the end of the experiment (Day 35) twenty birds from each group (5 birds/replicate) were selected randomly for blood samples collection and serum separation. Some immune parameters and antioxidant biomarkers were investigated. The collected birds were eviscerated after slaughtering to record some parameters of carcass yield. Results revealed that Supplementation of DOP to broiler diets improved significantly (p<0.05) final body weight and feed utilization. The best results recorded in group C which consumed 3% DOP and fortified with Xyalanse enzyme. DOP used significantly improves the antibodies titres against NDV (p<0.05). DOP fed broiler chickens showed significant increase in lysozymes and superoxide dismutase (SOD) activities (p<0.05). DOP supplemented groups recorded reduction significantly (p<0.05) in the metabolite malondialdehyde (MDA). Carcass weights, dressing percent, liver and abdominal fat weights were not affected significantly between groups. In conclusion, local Egyptian dried orange powder (DOP) can be included safely in broiler chicken diets up to 5% as unconventional
feed without any adverse effect. DOP has positive effects on broiler chicken immunity and antioxidant status.