Effect of different dietary concentrations of inorganic and organic copper on growth performance and lipid metabolism of White Pekin male ducks

Abstract

1. The effect of different dietary concentrations of inorganic and organic copper on performance and lipid metabolism of White Pekin ducks (WPD) was investigated from 1-49 d of age. A common basal diet was supplemented with 4, 8, 12 and 150 mg/kg of copper (Cu) from inorganic and organic sources to obtain 9 treatments, including 4 concentrations of Cu x two sources, and the unsupplemented control group. Each treatment contained 5 replicates of 9 male ducks each.

2. Supplementation of Cu at 8 mg/kg in inorganic form was adequate for growth of male WPD from 1-56 d of age. Inorganic Cu significantly decreased feed intake and improved feed conversion ratio, compared with the organic form.

3. Plasma Cu significantly increased, while plasma Zn significantly decreased, due to Cu supplementation. Organic Cu showed better efficacy than inorganic for improving liver Cu concentration, Cu excretion and apparent Cu retention.

4. Dietary Cu concentration significantly affected percentage blood and Hgb and abdominal fat deposition. In addition, inorganic Cu increased percentage blood and abdominal fat deposition compared with the organic source.

5. Supplementation of 150 mg/kg of Cu significantly decreased liver and meat lipids, cholesterol, and colour and tenderness of meat; while liver protein and moisture was increased. In addition, dietary 150 mg/kg of Cu supplementation significantly decreased plasma lipids, triglycerides and cholesterol, while increasing plasma AST and ALT.

6. Organic Cu was more potent for decreasing plasma triglycerides than the inorganic source. However, plasma cholesterol was only significantly decreased with the inorganic source of Cu, compared with the unsupplemented control.

7. The organic Cu was safer as a feed additive for WPD, especially at the lower concentrations up to 12 mg; while some mild to moderate changes may be developed at the higher doses, when fed at pharmacological concentrations as a growth promoter.