A total of 200 1-week-old Japanese quails were randomly allocated into five treatment groups, each consisting of 40 unsexed birds (five replicates, eight birds each). Quails were reared in traditional cages (90
40
40 cm), and feed and water were made available throughout the 5-week trial. The treatment groups were as follows: the 1st was fed basal diet, whereas the 2nd, 3rd, 4th, and 5th groups were fed with ration supplemented with nano zinc (Zn-NPs) at doses of 0.1, 0.2, 0.3, and 0.4 g/kg diet, respectively. Results showed that, a significant (p  .0001) improvement in body weight, weight gain, feed intake, and feed conversion ratio was observed in birds fed diets supplemented with 0.2 g/kg of Zn-NPs. Supplementation of Zn-NPs at doses of 0.1–0.3 g/kg diet demonstrated a positive impact on the activity of ALT, AST, and LDH. The liver profile parameters were not statistically influenced (p > .05) by dietary biological nano zinc, with the exception of total cholesterol (TC), high density lipoprotein (HDL), and low density lipoprotein (LDL). Also, dietary supplementation of biological Zn-NPs at concentrations of 0.1–0.3 g/kg diet demonstrated a positive impact on superoxide dismutase (SOD), glutathione peroxidase (GPX), malondialdehyde (MDA), immunoglobulin G (IgG), and immunoglobulin M (IgM). Dietary supplementation of Zn-NPs led to an increase in beneficial microbial populations. From the obtained results, Zn-NPs supplementation at 0.2 g/kg diet had a positive effect on the performance and physiological status of growing Japanese quails.