| Popis: |
The current dietary copper (Cu) requirement (8 mg/kg) of broilers is mainly based on growth, hemoglobin concentration, or hematocrit, which might not be the most sensitive indices to evaluate dietary Cu requirements of broilers. The present study was carried out to estimate dietary Cu requirements of broilers fed a conventional corn-soybean meal diet from 1 to 21 d of age using biochemical or molecular biomarkers. A total of 384 one-day-old Arbor Acres male broilers were randomly allocated to 1 of 6 treatments with 8 replicates and fed a Cu-unsupplemented corn-soybean meal basal diet containing 5.17 mg Cu/kg by analysis and the basal diet supplemented with 3, 6, 9, 12 or 15 mg Cu/kg as CuSO4⋅5H2O for 21 d. Regression analysis was performed to estimate the optimal dietary Cu level using the broken-line model. Dietary supplemental Cu level affected (P 0.05) on the growth performance, Cu contents in heart, kidney, pancreas and spleen, Cu- and zinc-containing superoxide dismutase (CuZnSOD) activity and ceruloplasmin content in serum, CuZnSOD and cytochrome c oxidase (COX) activities and ceruloplasmin, CuZnSOD, MAO A, MAO B, COX 4I1 and COX 1 mRNA and protein expressions in the above tissues of broilers. As dietary supplemental Cu levels increased, Cu contents in serum and liver increased linearly (P |
