title: Superior growth performance in broiler chicks fed chelated compared to inorganic zinc in presence of elevated dietary copper.
abstract: 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 < 0.001) and weight gain (12 %, P < 0.001) and the benefits were more pronounced in the presence of 250 mg/kg diet Cu. Experiment 2 was a dose titration of ZnSO4 · 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 < 0,05). Experiment 3 compared two organic Zn sources (Zn(HMTBa)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 < 0.01). Tibia Cu and liver Cu were significantly increased with 250 mg/kg dietary Cu supplementation (P < 0.01). No difference was observed between the two Zn sources.
  
  
  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.
authors.affiliation: Research and Development, Novus International, 20 Research Park Drive, Saint Charles, MO 63304 USA.
authors.forename: Junmei
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Research and Development, Novus International, 20 Research Park Drive, Saint Charles, MO 63304 USA ; Current affiliation: Poultry Technical Services, Adisseo USA, Alpharetta, GA 30022 USA.
authors.forename: Robert B
authors.initials: RB
authors.lastname: Shirley
authors.affiliation: Research and Development, Novus International, 20 Research Park Drive, Saint Charles, MO 63304 USA.
authors.forename: Julia J
authors.initials: JJ
authors.lastname: Dibner
authors.affiliation: Research and Development, Novus International, 20 Research Park Drive, Saint Charles, MO 63304 USA.
authors.forename: Karen J
authors.initials: KJ
authors.lastname: Wedekind
authors.affiliation: Research and Development, Novus International, 20 Research Park Drive, Saint Charles, MO 63304 USA.
authors.forename: Frances
authors.initials: F
authors.lastname: Yan
authors.affiliation: Research and Development, Novus International, 20 Research Park Drive, Saint Charles, MO 63304 USA.
authors.forename: Paula
authors.initials: P
authors.lastname: Fisher
authors.affiliation: Research and Development, Novus International, 20 Research Park Drive, Saint Charles, MO 63304 USA.
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Hampton
authors.affiliation: Research and Development, Novus International, 20 Research Park Drive, Saint Charles, MO 63304 USA.
authors.forename: Joseph L
authors.identifier: 0000-0002-9334-1650
authors.initials: JL
authors.lastname: Evans
authors.affiliation: Research and Development, Novus International, 20 Research Park Drive, Saint Charles, MO 63304 USA.
authors.forename: Mercedes
authors.initials: M
authors.lastname: Vazquez-Añon
keywords: Antagonism; Broilers; Chelates; Growth; Minerals; Organic; Performance