Effects of different dietary copper sources on laying hen performance and egg yolk cholesterol

An experiment was conducted using a total of 120 Lohmann Brown hens, 16 wk of age, to compare 3 different supplemental dietary Cu sources incorporating supraoptimal amounts of Cu (250 mg/kg) on layer performance, egg yolk cholesterol, and blood parameters. Layers were randomly allocated to 4 dietary treatments with 10 replications of 3 birds each for each treatment. Layers were fed diets containing 0 (control) or 250 ppm of Cu from Cu sulfate, Cu proteinate, or Cu lysine for 24 wk. No differences were observed among Cu sources for BW, egg mass, feed conversion, egg specific gravity, egg yolk cholesterol, plasma total cholesterol, high-density lipoprotein cholesterol, triglycerides, or glutathione peroxidase. Supplementation with 250 ppm of Cu sulfate improved egg production but decreased egg weight (P < 0.05) and feed intake (P < 0.01) as compared with the other diets. Supplementation with Cu proteinate resulted in decreased feed intake (P < 0.01), but egg production, egg mass, and egg weight were not changed as compared with the controls. Eggshell thicknesses of layers fed the Cu sulfate and Cu lysine diets were lower than the eggshell thickness of layers fed the control diet (P < 0.001). Copper contents of eggs and excreta were significantly (P < 0.001) increased regardless of Cu source as compared with birds fed the control diet. The results of this trial did not confirm the finding that Cu alters lipid metabolism and decreases cholesterol in the egg yolk. We conclude that increasing the dietary Cu intake through the use of different Cu compounds did not affect layer performance and cholesterol content of the egg yolk.