Research note: bioavailability of copper in cupric oxide, cuprous oxide, and in a copper-lysine complex.

Young chicks were used in a 2-wk feeding study to evaluate Cu bioavailability (relative to CuSO4.5H2O used as a reference standard) in analytical grade CuO, Cu2O, and in a feed-grade Cu-lysine complex. A basal corn and soybean meal diet was formulated to contain 290 mg Cu/kg, and graded levels (0, 75, and 150 mg/kg) of supplemental Cu were added from each Cu source. Based upon accumulation of Cu in the liver, Cu2O and Cu-lysine furnished Cu as efficiently as CuSO4.5H2O, but CuO provided no bioavailable Cu to the chicks.