Iron requirement of chicks fed a semipurified diet based on casein and soy protein concentrate.

An Fe depletion and repletion study was conducted to determine the Fe requirement of chicks fed a casein-dextrose diet containing soy protein concentrate. Weight gain, hematocrit, hemoglobin, and serum total Fe showed marked increases when graded levels (0, 5, 10, 20, 30, 40, and 50 mg/kg) of Fe from analytical grade FeSO4.7H2O were added to an Fe-deficient basal diet containing 46.5 mg Fe/kg. Subjecting the hemoglobin data to broken-line analysis indicated that the Fe requirement was 38.5 mg/kg of supplemental Fe (i.e., total dietary Fe of 85 mg/kg). Heart hypertrophy was observed in Fe-deficient chicks, but Fe supplementation (more than 20 mg/kg) alleviated the problem.