Superior growth performance in broiler chicks fed chelated compared to inorganic zinc in presence of elevated dietary copper

摘要

Background The goal of this study was to compare the antagonism of elevated dietary Cu (250?mg/kg) from CuSO₄ on three different Zn sources (ZnSO₄?·?H₂O; [Zn bis(?2-hydroxy-4-(methylthio)butanoic acid)], Zn(HMTBa)₂, a chelated Zn methionine hydroxy analogue; and Zn-Methionine), as measured using multiple indices of animal performance in ROSS 308 broilers. Methods Three experiments were conducted in broiler chicks fed a semi-purified diet. All birds were fed a Zn-deficient diet (8.5?mg/kg diet) for 1?wk, and then provided with the experimental diets for 2?wks. Results Experiment 1 was a 2 × 2 factorial design with two levels of Cu (8 vs. 250?mg/kg diet from CuSO₄) and two Zn sources at 30?mg/kg [ZnSO₄?·?H₂O vs. Zn(HMTBa)₂]. Elevated Cu impaired growth performance only in birds fed ZnSO₄. Compared to ZnSO₄?·?H₂O, Zn(HMTBa)₂ improved feed intake (12?%; P 4?·?H₂O and Zn(HMTBa)₂ at 30, 45, 60, and 75?mg/kg diet in the presence of 250?mg/kg CuSO₄. Feed:gain was decreased and tibia Zn was increased with increasing Zn levels from 30 to 75?mg/kg. Birds fed Zn(HMTBa)₂ consumed more food and gained more weight compared to birds fed ZnSO₄, especially at lower supplementation levels (30 and 45?mg/kg; interaction P 2 vs. Zn-Methionine) at 30?mg/kg with or without 250?mg/kg CuSO₄. No interactions were observed between Zn sources and Cu levels on performance or tissue mineral concentrations. High dietary Cu decreased weight gain ( P Conclusions Dietary 250?mg/kg Cu significantly impaired feed intake and weight gain in birds fed ZnSO₄?·?H₂O_, but had less impact in birds fed Zn(HMTBa)₂. No difference was observed between the two organic zinc sources. These results are consistent with the hypothesis that chelated organic Zn is better utilized than inorganic zinc in the presence of elevated Cu.