This experiment was conducted to evaluate the effects of dietary turmeric rhizome powder (TP) on performance, blood metabolite, immune system, antioxidant status, and relative weight of organs in pre and post heat stressed broilers. 264 day-old male Arian broiler chicks were randomly allotted to 3 dietary treatments containing 0, 0.4 or 0.8% turmeric powder(TP). Each diet was fed to four replicates of 22 birds each. Heat stress was applied for 5 hours (33oC) from 28-42d. Two birds from each replicate were randomly selected and blood samples were taken to collect the serum, plasma and whole blood. These were slaughtered to determine relative weigh of organs pre (28d PHS) and after heat stress(42d AHS). TP did not affect feed intake, body weight, FCR, production index, protein and energy efficiency ratio of broilers. Blood cholesterol and LDL decreased and blood HDL increased when fed TP in PHS and AHS birds. TP did not affect serum triglyceride, protein, antibody production against SRBC, IgG, IgM and ND in PHS and AHS. TP suppressed the enzyme activity of LDH, AST, ALT, and ALP of heat stressed birds. The enzyme activity of CK in AHS and SOD in PHS were not affected by TP diets. TP diets increased blood activity of GPx and SOD and decreased blood TBARS index. The H:L ratio, relative weight of bursa of fabircus and abdominal fat decreased in birds fed TP diets. TP diets did not altered percentage of bone Ash, and P of heat stress broilers, however it increased bone Ca of heat stressed broilers. It is concluded that the supplementation of TP to diets may decreased the activity of dehydrogenase enzyme, stressor index, and improved the antioxidant status without affect performance and immune system of heat stressed broilers.

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