Effects of in ovo Injection of Nano Zinc Oxide on the Hatchability, Immunity and Antioxidant Responses, and Relative Gene Expressions of Interleukin 2 and 12 in Broiler Chickens

This experiment was conducted to examine the effects of in ovo injection of nano zinc oxide (Nano-ZnO) on hatchability, immunity responses, and performance in broiler chickens. A total of 432 fertilized eggs (Ross 308) were assigned to a completely randomized design with four treatments by four replications and 27 eggs in each replicate. Treatments included: 1) negative control (no injection), 2) positive control- no treatments with injection of solutions (20 μL saline), 3) 20 μL of Nano-ZnO (0.5 mg of Nano-ZnO in 50 mL saline), and 4) 20 μL of Nano-ZnO (0.6 mg of Nano-ZnO in 50 mL saline). Results showed that hatcha-bility (P=0.002) and weight of hatched chicks (P=0.0001) decreased in treatments two and three compared to negative control. However, embryonic mortality were increased in early (≤7 d) and late (17-21 d) stages in comparison with the negative control (P=0.008). Fourteen days after vaccination, antibody titers of avian Influenza (P=0.025) and Newcastle (P=0.002) disease were increased in chickens that received Nano-ZnO compared to control groups. Relative gene expression levels of interleukin-2 (IL-2) (P=0.002) and 12 (P<0.05) were greater in treatment 3 compared to other treatments. Although in ovo injection of Nano-ZnO reduced hatchability at first glance, this was the result of injection, but it did not reduce the hatchability and chickens’ weight compared to positive control. In ovo injection of Nano-ZnO increased embryonic mor-tality, and improved humoral and cellular immune responses and weight of the spleen, which indicates the positive effects of injections and confirms the hypothesis of the study.