Effect of high dietary copper dosage on laying performance, egg quality, and content of cholesterol and copper in hen's eggs

Experiment was conducted to investigate the possibility of lowering the yolk cholesterol of the egg by supplementing with pharmacological levels of Cu (8, 300, 350, 400 or 450 mg/kg diet) as cupric sulfate pentahydrate. ISA Brown 2000 hens, 34 to 45 w/k of age, were fed with feeding trial for 84 d (3*28 d period). Egg production was significantly increased fitted a quadratic model (P LT 0.05) with 400 mg Cu/kg diet giving a positive response and level of 450 mg Cu/kg diet giving a progressively negative response in the third 4-wk period. Similar response were also observed but were not significant (P GT 0.05) in the first, second and the over all periods. Feed conversion rations (g feed/g egg), closely reflecting hen-day egg production, tended to quadratically respond (P GT 0.05) to supplemented Cu levels with the maximum efficiency at 300 mg/kg diet and leveled off at 350 mg Cu/kg diet or higher. Yolk weight, specific gravity, egg shell thickness and Haugh Units were not consistently affected for all periods of testing. Egg weight were linear (P LT 0.05) decreased by feeding at over 350 mg Cu/kg diet for all period of testing. Egg yolk cholesterol were deceased fitted both linear and quadratic models (P LT 0.05) with 350 mg Cu/kg diet, feeding more than 400 mg Cu/kg diet resulted no further declines in egg cholesterol for all periods of testing. Cu content of egg fitted both linear and quadratic models (P LT 0.05) with 400 mg Cu/kg diet giving positive maximum increased in accumulation Cu in hen's eggs and added more than 400 mg Cu/kg diet resulted no further increase in CU in hen's eggs for all periods of testing. A significant interaction (P LT 0.05) between egg yolks quantity and periods showed a greater reduction at a latter time. A similar observation was found with the Cu content in hen's eggs. If a small reduction in performance can be accepted, the addition of 400 mg Cu/kg diet might be beneficial in reducing the egg yolk cholesterol and maximum accumulation Cu in hen's egg for designed or healthy eggs application in egg Industry.