Calves have been raised for veal on liquid diets containing different amounts of iron. A concentration of 25-30 mg soluble iron/kg dietary dry matter provided sufficient haemaglobin for normal appetite, growth and oxygen transport, and also produced carcases light coloured enough for the veal trade. When anaemia was induced in calves or sheep the first measurable response from the animals was a fall in appetite which provided a more sensitive indicator than more complicated physiological or biochemical measurements.