Iron is an important mineral for animal development and function. The present study was carried out to evaluate the effect of FeSO4 replacement with cysteine-coated Fe3O4 nanoparticles in quail. We hypothesised that the iron nanoparticles could be used as a dietary supplement. The quails were randomly allotted to five dietary treatments with four replicate pens and 10 birds per pen. The treatments consisted of: negative control without any iron supplementation, positive control with 120mg/kg of FeSO4 and three experimental groups that contained 1.2, 12 and 120 mg/kg of L-cysteine coated iron oxide nanoparticles, organic iron, in their diet, respectively. The least weight gain was recorded in the negative control group. Similar weight gain, FCR, haematological and biochemical parameter results between the experimental and positive control groups show that organic iron successfully performed the biological role of iron in the quail. We concluded that 1.2 mg/kg cysteine-coated Fe3O4 nanoparticles are required and sufficient for quails’ optimal maintenance and growth. The results confirm that cysteine-coated Fe3O4 nanoparticles can be used as an iron source in the quail diet.