Using antibiotics in poultry diets as growth promoters was reported to have harmful effects on consumers, so the current study was done to monitor the impact of dietary supplementation of antimicrobial black cumin oil (BCO) on carcass traits, growth performance, biochemical components, and ileal microbial populations of growing Japanese quails. Three hundred growing Japanese quails were used with three different treatments (0, 0.50, and 1.0 g BCO/g diet). Birds fed diet supplemented with 0.5 g BCO/kg diet showed significant increase in body weight comparing with the control and other treatment group. The daily feed intake and feed conversion ratio were significantly increased side by side with increasing BCO level in the diet. The majority of carcass characteristics were maximized by supplementing the quail diet with 0.5 g BCO/kg. Moreover, liver functions, anti-oxidative capacity, lipid profile and anabolic hormones showed significant improvement in BCO-treated diets in a dose-dependent manner. The BCO showed highest antibacterial effect against Escherichia coli and Salmonella enterica. The ileal bacterial populations, i.e., total bacterial count (TBC), coliform, Salmonella species, and Escherichia coli were decreased in birds supplemented with BCO 0.5 and 1.0 BCO g/kg compared with the control diet. Based on the aforementioned results, conclusion could be drawn that supplementing quail with BCO in their diet could improve productive performance traits and enhance health aspect of the birds.
Keywords: Antioxidant; Black cumin oil; E. coli; Growth; Quail; Salmonella.