RESUMO
A study was conducted to investigate the influence of copper administration in ovo to chicken embryos and/or supplied in drinking water to growing chickens in the form copper nanoparticles (Cu-NP) or copper sulphate (CuSO4 ). The fertilised eggs were assigned to three groups (n = 50 per group): control (not injected), injected with 50 mg/kg Cu-NP or with 50 mg/kg CuSO4 at day 1 of incubation. Thereafter, 126 one-day-old broiler chickens were randomly assigned to seven post-hatched groups: control not injected and not provided with Cu in the drinking water, injected with 50 mg/kg Cu-NP + 20 mg/kg in water, not injected + 20 mg/kg Cu-NP in water, injected with 50 mg/kg CuSO4 + 20 mg/kg in water, not injected + 20 mg/kg CuSO4 in water, injected with 50 mg/kg Cu-NP and injected with 50 mg/kg CuSO4 . The experiment was carried out from day 1 to 35 post-hatching. The in ovo injection of Cu improved the final body weight, average daily gain and feed conversion ratio in relation to the control group. Conversely, the provision of Cu in the drinking water had less of an effect on growth performance in comparison with the injected groups. A significant improvement was shown in energy and nitrogen utilisation, being better for Cu-NP than CuSO4 . The cholesterol, urea and glucose levels in the blood were reduced by Cu-NP treatment in relation to the other groups. The relative weight of the liver was decreased, while bursa of Fabricius was increased in Cu groups in relation to the control group. Cu excretion was only reduced in chickens injected with 50 mg/kg Cu-NP + 20 mg/kg in water. The immune-related genes were not affected by the treatments. The in ovo injection of Cu-NP might improve broiler performance more efficiently than the injection of CuSO4 or the provision of Cu-NP and/or CuSO4 in drinking water.
