Zinc bioavailability it tetrabasic zinc chloride and the dietary zinc requirement of young chicks fed a soy concentrate diet

ABSTRACT Three chick assays were conducted to de-termine a bioavailable Zn requirement and to establish a Zn relative bioavailability (RBV) value for tetrabasic Zn chloride [TBZC, i.e., Zn5Cl2(OH)8]. In Assay 1, 8-d-old chicks were fed a Zn-deficient soy concentrate diet (8.8 mg/kg bioavailable Zn) supplemented with 0, 5.81, 10.81, 15.10, and 20.25 mg Zn/kg from ZnSO47H2O for 14 d to establish a linear response range and estimate a bioavaila-ble Zn requirement. Weight gain of chicks increased lin-early (P < 0.01; r2 = 0.99) when the first three levels of Zn were fed. Broken-line analysis of the weight gain data indicated a bioavailable Zn requirement of 22.4 mg/kg. In Assay 2, RBV of Zn in TBZC was determined by multiple-(Key words: zinc sulfate, tetrabasic zinc chloride, bioavailability, chick, zinc requirement