Dietary iron and broiler performance.

1. An experiment was conducted with female broilers from 1 to 39 d of age in which the effects of increasing amounts of extra dietary ferrous sulphate on growth performance, some haematological measurements and Fe, Zn and Cu status were studied. A conventional maize-soyabean diet (107 mg Fe/kg) was supplemented with 0, 20, 60, 180, 540 and 1620 mg Fe to provide 6 treatments. 2. Weight gain responses rose to a plateau between 20 and 60 mg added Fe/kg diet, but further additions of Fe increasingly depressed growth. 3. In this study the apparent Fe requirement was 100 mg/kg diet (80 mg from dietary components and 20 mg Fe from supplement). 4. The efficiency of food utilisation decreased linearly, while the proportion of chicks affected by leg weakness increased. 5. In blood, the haemoglobin concentration increased slightly with extra dietary Fe. 6. The iron content of the liver increased with higher dietary Fe supplementation. Furthermore, increased liver Fe content was associated with a higher Zn content in the liver. 7. This study indicated that a maize-soyabean diet containing about 30% more Fe than has generally been accepted to be adequate for healthy broilers was still marginal in Fe concentration.