Feeding Nigella sativa oil to broilers affects their performance, serum constituents and cecum microbiota

The objective of this study was to assess the effect of supplementation of Nigella sativa oil (NSO) as a growth promoter in broiler diets. A total of 300 unsexed one-day-old Arbor Acre broiler chicks were randomly divided into five treatment groups (60 chicks/group). Each group was divided into five replicates with 12 chicks per replicate. Group 1 was fed on the basal diet with no additives (control). Group 2 was fed the basal diet supplemented with oxytetracycline (OTC) at the level of 50 ppm. Groups 3, 4 and 5 were fed the basal diet supplemented with 500, 1000 and 1500 ppm NSO, respectively. Birds fed on 1500 ppm NSO diet showed the heaviest body weight at 14, 28 and 42 days of age. Feed conversion ratio was significantly improved at all ages with the inclusions of OTC and NSO generally superior to the control group. The relative weight of spleen was increased significantly by the addition of NSO at various levels. However, relative weights of thymus and bursa were not altered by the treatments. Total bacterial count, total yeast and moulds count, E. coli and salmonella spp. counts were reduced significantly, whereas the total lactic acid bacteria count was increased in OTC and NSO groups compared with control. Nigella sativa oil could be used in broiler chicken feeds as a natural alternative to antibiotic growth promoters to improve gut health and consequently growth performance.