This study was carried out to explore the influence of black and red pepper oils (BRPO) as a natural antibacterial agent on growth, carcass, liver and kidney functions, lipid profile, immunity and antioxidant indices of growing quails. A total of 225 Japanese quails (1-week-old) were haphazardly divided into 5 groups, each group consists of 45 unsexed birds with 5 replications (9 birds each). The first group was fed basal diet (control), and the 2nd, 3rd, 4th and 5th groups fed rations containing BRPO (0.4, 0.8, 1.2 and 1.6 g/kg diet respectively). During 1-3 weeks of age, body weight gain (BWG) and feed conversion ratio (FCR) were improved with dietary BRPO. During 3-5 and 1-5 weeks of age, BWG was quadratically increased with BRPO supplementation. Also, a quadratic improvement in FCR was observed with BRPO during the overall period. There were no statistical differences in all carcass parameters due to BRPO treatment. Feeding quails on rations enriched with BRPO was linearly influenced liver functions. The highest BRPO levels (1.2 and 1.6 g/kg diet) minimized plasma content of total cholesterol (TC) and triglyceride (TG) respectively. Malondialdehyde (MDA) was reduced in quails fed diets supplemented with BRPO. In apart from the highest level of BRPO, complement 3 (C3) was increased with increasing BRPO level. Birds fed diets enriched with BRPO exhibited lower colonization of TBC, lactobacilli, coliform, Salmonella and E. coli than those in the control group. It could be concluded that dietary BRPO can positively affect quail growth, liver and kidney functions, antioxidant and immunity parameters, lipid profile and lipid peroxidation as well as pathogenic bacteria.

Keywords: antioxidant; blood; growth; immunity; pathogens; quail; red and black pepper oils.