Farhad Hajializadeh - Graduate Student, College of Veterinary Medicine, Urmia Branch, Islamic Azad University, Urmia, Iran
Hasan Ghahri - Department of Animal Science, College of Veterinary Medicine, Urmia Branch, Islamic Azad University, Urmia, Iran
Alireza Talebi - Department of Poultry Health and Diseases, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran

This experiment was carried out to investigate the effects of different levels chromium picolinate (CrPic) and chromium nanoparticles (nano-Cr) on the performance and immune function of broilers under heat stress condition. A total of ۳۲۰ Ross ۳۰۸ broiler chicks (from ۲۱ to ۴۲ days) were assigned randomly into eight treatment groups (four replicates per treatment, and ۱۰ chicks per replicate) and be reared at either thermoneutral (۲۱ ˚C) or heat stress (۳۶ ◦C). The treatments were control (T۱) group without supplementation and heat stress, T۲ as a heat stress group without supplementation, T۳, T۴ and T۵ groups which were supplemented with ۵۰۰, ۱۰۰۰ and ۱۵۰۰ ppb CrPic in diet with heat stress, respectively and T۶, T۷ and T۸ groups which were supplemented with ۵۰۰, ۱۰۰۰ and ۱۵۰۰ ppb nano-chromium in diet under heat stress, respectively. Supplementation of chromium and nano-chromium improved performance including weight gain and feed conversion ratio of heat-stressed chickens. Antibody titers against avian influenza (AI) and infectious bronchitis (IB) at ۲۱ to ۴۲ days of age in broilers fed supplemental chromium and nano-chromium were higher than broiler chickens fed control diet (p < ۰.۰۵). Nano-chromium supplementation at level of ۱۰۰۰ ppb and CrPic at level of ۱۵۰۰ ppb improved the antibody titers against AI and IB of broilers under heat stress conditions. It can be concluded from these findings that dietary supplementation of CrPic and nano-Cr can improve performance and antibody titers against AI and IB under heat stress conditions in broilers.

Avian influenza, Chromium, Heat stress, Infectious bronchitis, Nano-chromium