А. orcid.org/0000-0002-5125-5981) Acknowledgements: Chemical analysis was performed in the Laboratory of Agroecology of Nanomaterials and Test Center of AllRussian Research Institute of Beef Cattle Breeding (accreditation certificate RA. <...> Ionic forms commonly used for correction are characterized by low bioavailability, prooxidant effect, and high toxicity in vivo. <...> That is why low-toxic sources of essential chemical elements are of particular interest, including nanocrystalline metals. <...> We firstly assessed the efficient of nanosized copper on the model of broiler chickens. <...> A comparative study of productive and biological effects of copper nanoparticles (CuNPs) and сopper sulfate was carried out on Smena 7 chickens of 14-42 days of age using different administration methods. <...> Hematologic and biochemical parameters and elemental composition of tissues were assessed. <...> We revealed an increase in red blood cells and hemoglobin and decrease of platelets at the highest doses of Cu NPs administrated orally or intramuscularly. <...> The biochemical blood parameters assessed indicated an enhancement of plastic processes in the body and, as a consequence, an increase in the growth rate under Cu NPs administration. <...> The difference of the total protein compared to the control (33.6 %, p < 0.05) was the highest when Cu NPs injected at a dose of 2 mg/kg which increased the supply of protein synthesis. <...> The albumin level was higher in 28-day old chicks injected with Cu NPs (2 and 0.2 mg/kg). <...> A replacement of dietary CuSO4 with dietary Cu NPs led to an increase in the growth rate. <...> When Cu NPs fed, the found biochemical parameters indicated strengthening of energy and synthetic processes in the body, and therefore, an increase in the poultry growth. <...> Dietary Cu NPs at 0.7 mg/kg was not enough to highly stimulate the poultry growth and resulted in the weight gain which was lower than in the poultry fed with Cu NPs at 1.7 mg/kg but higher (by 8.5-18.4 %, p < 0.01 to p < 0.01) as compared to the poultry not fed with Cu NPs. <...> Thus, the promoting effect depends on the form of copper source. <...> The Cu NPs effectiveness under enteral administration at 1.7 mg/kg or intramuscular double injections at 0.2 mg/kg was superior to that of dietary copper sulfate. <...> Keywords <...>