Fatty acid profiles of Nigella seed oil (NSO) as alternative growth promoter and its effects on performance, and blood constituents and immune response of broiler chickens were determined in comparison to antibiotic Zinc bacitracin (ZnB). A total of 175 unsexed day old broiler chicks were randomly distributed among 5 treatments, each was replicated 7 times with 5 chicks per replicate during 1-45 days of age. The basal diet was administered without supplements (Control group) or supplemented with Zinc bacitracin (ZnB group) or Nigella seed oil at 0.5 (NSO_0.5 group), 1.0 (NSO_1.0 group) and 1.5 g/kg (NSO_1.5 group). The NSO replaced the same percent of vegetable oil blend in the experimental diet. Unsaturated fatty acids in NSO were 68.9% of which monounsaturated fatty acids were 35.3% and polyunsaturated fatty acids 33.1%. The oleic acid is the dominant fatty acids in NSO (33.6%) followed by linoleic (33.1%). The antioxidant inhibition and total phenolic compounds of NSO were found to be 80% and 14.5 mg/g, respectively. Feed intake and feed conversion ratio (FCR) were not significantly affected by different dietary additives, but NSO_ 0.5 improved FCR numerically by 1.4% and European production index significantly by 5.4% compared to the control. Antibody titer to Newcastle disease virus and infectious bursa disease was significantly increased by NSO_1.5 supplementation compared to the NC group, but differences from ZnB and other NSO concentrations was not significant. In conclusion, NSO_0.5 could be used as an alternative growth promoter to ZnB in broiler diets yielding comparable or better growth performance, and immune response than ZnB.
