Bovine hemoglobin as the sole source of dietary iron does not support adequate iron status in copper-adequate or copper-deficient rats

This experiment was designed to determine whether dietary hemoglobin (Hgb) iron (Fe) could sustain normal Fe status in growing rats adequate or deficient in copper (Cu). Forty-eight weanling rats were divided into 3 groups, each consisting of 16 animals. One group was fed a diet containing 40 mg Fe/kg as ferrous sulfate (FeSO4). A second and a third group were fed 40 and 70 mg Fe/kg, respectively, as bovine Hgb. Each of these groups was divided into 2 subgroups of 8 rats each and fed 5.0 or less than 0.5 mg Cu/kg. After 4 weeks, Cu and Fe statuses were assessed. Rats fed 40 mg Fe/kg as Hgb were anemic, but not when fed 70 mg Fe/kg as Hgb. Rats fed CuD diets also were anemic compared to CuA rats. Rats fed Hgb Fe at 40 mg/kg had lower (P < .001) Fe concentrations in serum and spleen compared with those fed FeSO4; however, these parameters were normal in rats fed Hgb Fe at 70 mg/kg. Regardless of the dietary Hgb Fe level, Fe concentrations in the intestinal mucosa, liver, and kidney were significantly lower than in rats fed FeSO4. Copper was significantly (P < .001) lower in the mucosa, serum, liver, spleen, and kidney of CuD rats than CuA rats regardless of the dietary Fe source. Iron was significantly (P < .001) elevated in mucosa and liver, but lower in serum (P < .001) and kidney (P < .040) of CuD rats than in CuA rats. Heme oxygenase protein was significantly (P < .001) higher in rats fed Hgb Fe than in those fed FeSO4, but was not affected by CuD. This investigation demonstrates that adequate Fe status cannot be maintained in the growing rat with Hgb as the sole source of dietary Fe.