SIZOVA1, 2 1All-Russian Research Institute of Beef Cattle Breeding, Federal Agency of Scientific Organizations, 29, ul. 9 Yanvarya, Orenburg, 460000 Russia, e-mail sizova-l78@ya.ru, vniims.or@mail.ru; 2Orenburg State University, 13, prosp. <...> А. orcid.org/0000-0002-5125-5981) Acknowledgements: We thank Dr N.N. Glushchenko (Institute of Energy Problems of Chemical Physics, RAS, Moscow) for kindly providing the Fe nanoparticles used in the study. <...> Hematological studies were performed using standard techniques in the Laboratory of Agroecology of Nanomaterials and Test Center of All-Russian Research Institute of Beef Cattle Breeding (accreditation certificate RA. <...> RU.21PF59 of 12/02/15) Supported by Russian Scienсe Foundation (project ¹ 14-16-00060) Received September 1, 2016 A b s t r a c t The prospects of using metal nanoparticles to stimulate productivity of farm animals are widely discussed. <...> However, nano-sized materials exhibit various negative properties, such as prooxidant effects, and can provoke apoptosis and kidney damage. <...> A possible approach is the use of ultrafine materials in combination with agents leveling adverse effects of nanoparticles. <...> For the first time we studied the prospects of joint use of iron and arginine nanoparticles, the mechanism of their interaction and influence on the productivity of poultry and demonstrated that their simultaneous application promote live weight gain. <...> The poultry was injected twice (after 2 week intervals) with iron nanoparticles and fed either with dietary arginine (the amino acid which is known to influence metabolism and immune response and considered as conditionally essential for inflammatory and oxidative stress), or the mixture of arginine, lysine and methionine. <...> Withal, the nanoparticles and amino acids when applied separately resulted in lower weight gain, and at the end of the experiment the body weight of broilers fed with dietary arginine (group II) and those injected with iron nanoparticles (group III) increased by 6.1 and 5.9 % (P 0.05), respectively. <...> Intramuscular administration of iron nanoparticles (the poultry groups III, IV and VI) promoted the immune response that was manifested in enhanced level of leukocytes — by 8.12; 10.50 and 3.88 % (P 0.05), respectively, on the day 1, and by 7.3; 8.19 and 4.00 % (P 0.05), respectively, in a week. <...> Singly injected <...>