Effects of dietary copper on performance, serum and egg yolk cholesterol and copper residues in yolk of laying chickens

Abstract

A 294-day study was conducted to determine the effects of organic and inorganic copper (Cu) sources on laying performance, blood and yolk cholesterol and Cu accumulation in the yolk of laying hens. 480 Kabir® laying hens (20 weeks old) reared for 294 days in three phases (early, mid and late lay) were used. They were randomly allocated to six dietary groups of 80 birds split into four replicates of 20 birds each The diets consisted of a basal diet (containing 37.24 mg kg-1 Cu) supplemented with organic Cu (Cu proteinate; Cu-P) or inorganic Cu (Cu sulphate pentahydrate; CuSO4 ) fed at 3 dietary concentrations (50, 100 and 150 mg kg-1). Data on laying performance, blood and yolk cholesterol and Cu accumulation in the yolk were collected and subjected to Completely Randomized Design of the Analysis of Variance, laid out in 2 × 3 factorial arrangements. CuSO4 supplementation resulted in poor (P <0.05) feed conversion ratio (feed/dozen eggs and feed kg eggs-1) and reduced (P <0.05) hen day egg production when compared to Cu-P. High concentration of Cu resulted in reduced hen day egg production. No signifi cant (P >0.05) effect of Cu sources and concentration was observed for body weight, weight gain and daily feed intake. The blood cholesterol and triglyceride level were signifi cantly (P <0.05) reduced in birds fed diets with Cu-P. The blood cholesterol level decreased as the Cu concentration increased. More Cu was accumulated in the yolk of birds fed Cu-P. The blood and yolk cholesterol levels were signifi cantly lower (P <0.05) in birds fed Cu-P than CuSO4 . It was evident that Cu-P was more bioavailable than CuSO4 owing to higher accumulation of Cu in the yolk of the birds fed Cu-P. Cu-P at 50 mg kg-1 is recommended in the diets for laying hen. A high level of Cu-P (150 mg kg-1) in laying hens’ diets was effective for cholesterol reduction in yolk and blood of experimental birds.