BIOAVAILABILITY OF ZINC IN 2 ZINC-SULFATE BY-PRODUCTS OF THE GALVANIZING INDUSTRY

Two Zn depletion/repletion assays were conducted with chicks to determ ine the relative bioavailability (RBV) of Zn from two new by-products of the galvanizing industry. Using a soy concentrate-dextrose diet, sl ope-patio methodology was employed to evaluate two different products: Fe-ZnSO4 . H2O with 20.2% Fe and 13.0% Zn, and Zn-FeSO4 . H2O with 14 .2% Fe and 20.2% Zn. Feed-grade ZnSO4 . H2O was used as a standard. We ight gain, tibia Zn concentration, and total tibia Zn responded linear ly (P < 0.01) to Zn supplementation from all three-sources. Slope-rati o calculations based on weight gain established average Zn REV values of 98% for Fe-ZnSO4 . H2O and 102% for ZnFeSO4 . H2O, and these values were not different (P > 0.10) from the ZnSO4 standard (100%). Slope-r atio calculations based on total tibia Zn established average Zn REV v alues of 126% for Fe-ZnSO4 . H2O and 127% for Zn-FeSO4 . H2O and these values were greater (P < 0.01) than those of the ZnSO4 standard (100% ). It is apparent that both mixed sulfate products of Fe and Zn are ex cellent sources of bioavailable Zn.