Effects of high supplemental dietary copper on laying performance, egg yolk cholesterol and blood plasma lipids

Abstract

This study was conducted to determine the effect of high supplemental dietary copper on laying performance, egg yolk cholesterol and blood plasma lipids. One hundred and sixty laying hens were placed in cages, and 8 birds were grouped per replicate, in a total of 5 treatments. Hens were fed a commercial diet supplemented as copper sulfate with 0, 200, 400, 600 and 800 mg of copper/kg for a period of 6 weeks. Egg weight, egg production, feed intake and feed conversion were not significantly affected by the supplemental copper up to 400 ppm. At 600 and 800 mg/kg copper significantly reduced egg weight, egg production and feed intake. Egg shell quality, estimated as egg shell weight (g and % of egg weight) and egg shell thickness, was significantly decreased only at the higher supplemental copper level (800 ppm). Plasma concentrations of triglycerides and HDL cholesterol showed an inversion relationship when excess of supplemental dietary copper was fed. At the level of 800 ppm copper determined a significant reduction in plasma triglycerides (705 mg/dL) and a significant increase in plasma HDL cholesterol (9.7 mg/dL) as compared to the control group (1,643 and 4.5 mg/dL, respectively). Egg yolk cholesterol calculated on original or dry matter basis was significantly increased by feeding the higher level of supplemental copper (800 ppm) showing values of 14.83 and 27.70 mg/dL, respectively, as compared to the control group (12.35 and 23.08 mg/dL, respectively). The effect of high dietary level of copper on reduction of egg yolk cholesterol was not confirmed in this study. Further researches are recommended.