Dietary iron effects on broiler breeder performance and egg iron contents

Sixty Cobb 500 broiler breeder hens, 22 wks of age, were individually placed in galvanized cages and fed diets without iron (Fe) supplementation for 12 weeks. Birds were then randomly allocated to six dietary treatments with the same nutrient profile, except for Fe, in a factorial of two diets (all vegetable and meat and bone meal - MBM) and three Fe sources (control, inorganic and complexed). The all-vegetable diet was formulated with maize, soybean meal and wheat bran whereas the MBM containing diet included 25 g MBM/kg. The control diets were not supplemented with Fe, whereas inorganic and complexed diets had 60 mg Fe/kg as supplement from Fe2+ sulfate or Fe-amino acid (Fe-AA), respectively. Diets were provided for three periods of four weeks each and eggs were collected daily. Hen day egg production and Fe content of yolk and albumen were analyzed using a two-way anova with repeated measures. Egg production was lowest (P<0.05) for birds fed diets without Fe supplementation but no difference (P>0.05) was detected between the inorganic and complexed Fe sources. Contents of Fe in yolk increased from the first to the second period (P<0.001) without changes afterwards, whereas it decreased in albumen from the second to the third period (P<0.001). Egg yolk Fe concentration was highest for the MBM containing diet supplemented with Fe-AA and lowest for the all-vegetable diet not supplemented with Fe, with all the other treatments being intermediate (P<0.001). Albumen Fe concentration increased when Fe was supplemented to diets containing MBM, but further increases depended on the use of Fe-AA (P<0.001). It is concluded that breeder hens have reduced hen day egg production when diets are not supplemented with Fe and that Fe supplementation can affect yolk and albumen contents depending on the presence of MBM in the diet.