RESUMEN
Copper (Cu) is widely used at high levels as growth promoter in poultry, the alternative source of Cu to replace the high level of inorganic Cu at poultry farm remains to be determined. Three floor pen experiments were conducted to evaluate the effects of Cu methionine hydroxy-analogue chelate (Cu-MHAC, MINTREX®Cu, Novus International, Inc.) on growth performance and gut health in broilers in comparison to CuSO4 and/or tribasic copper chloride (TBCC). There were 3 treatments in experiment#1 (0, 30 and 75 ppm Cu-MHAC) and experiment#2 (15 and 30 ppm Cu-MHAC, and 125 ppm CuSO4), and 4 treatments in experiment #3 (15 and 30 ppm Cu-MHAC, 125 ppm CuSO4 and 125 ppm TBCC) with nine replicates pens of 10-13 birds in each treatment. The levels of other minerals were equal among all treatments within each experiment. All birds were orally gavaged with a coccidiosis vaccine at 1x recommended dose on d0 in experiment#1 and #2 and 10x recommended dose on d15 in experiment #3. Data were analyzed by one-way ANOVA, means were separated by Fisher's protected LSD test. A p ≤ 0.05 was considered statistically different. In experiment #1, 30 and 75 ppm Cu-MHAC improved FCR during grower phase, increased jejunal villus height and reduced jejunal crypt depth, 30 ppm Cu-MHAC increased cecal Lactobacillus spp. abundance in 41 days broilers. In experiment #2, compared to CuSO4, 15ppm Cu-MHAC increased cumulative performance index in 28 days broilers, 15 and/or 30 ppm Cu-MHAC improved gut morphometry, and 30 ppm Cu-MHAC reduced the abundance of E. coli and Enterobacteriaceae in cecum in 43 days broilers. In experiment #3, 15 ppm and 30 ppm Cu-MHAC improved FCR vs. CuSO4 during starter phase, reduced the percentage of E. coli of total bacteria vs. TBCC, 30 ppm Cu-MHAC increased the percentages of Lactobacillus acidophilus, Lactobacillus spp. and Clostridium cluster XIVa of total bacteria vs. both CuSO4 and TBCC in the cecum of 27 days broilers. In summary, low doses of Cu-MHAC had comparable growth performance to high dose of TBCC and CuSO4 while improving gut microflora and gut morphometry in broilers subject to coccidiosis vaccination or coccidia challenge, indicating that low doses of bis-chelated Cu could be used as a complimentary strategy to improve animal gut health.
RESUMEN
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.