Iron metabolism in the veal calf. The availability of different iron compounds

Abstract

1. The haematological status of Ayrshire bull calves reared on fat-supplemented skim milk from about 17 d of age has been examined. The calves were moderately anaemic after an 11-week experiment and it was shown that their performance was related to their blood haemoglobin concentration. 2. The relative availabilities of iron from FeSO 4 , ferric citrate, ferric-ethylenediaminetetra-acetate and iron phytate were compared at a supplementary dietary concentration of 30 μg Fe/g. No significant differences were noted between the three soluble Fe sources but the Fe of the insoluble iron phytate was less available. 3. The decreases in blood haemoglobin concentrations in all calves were greatest in the early weeks of the experiment. In calves given supplementary Fe, however, there was generally an improvement in haematological status after 6 weeks. Plasma Fe concentrations fell to 0·20 μg/ml in the most deficient animals. Total Fe binding capacities averaged about 10 μg Fe/ml in the later stages of the experiment. 4. Some of the calves were copper-deficient, and in some animals the effects of dietary Cu supplementation on both Cu and Fe metabolism were studied. About 50% of the supplementary Cu was retained in the livers of the calves. 5. A dietary intake of 40 μg Fe/g milk powder appears to be sufficient to prevent all but a very mild anaemia, provided the Fe is presented in soluble form.