The work of Dewey (1977), in Australia, showed that the oral administration of cupric oxide wire (CuON), in lengths of between 5-10 mm and a mean diameter of 0.5 mm, at a dosage rate of 10 g in a gelatin capsule to mature sheep, produced a steady increase in liver copper (Cu) concentrations over 16 days to levels over 1000 mg/kg DM above the initial levels. The 'needles' lodged primarily between the abomasal folds and, by 64 days, were no longer detectable. In grazing conditions, a dose of 20 g was administered to sheep. At neither dosage level were deleterious effects noted. Suttle (1981) administered 0.5 g CuON to hypocupraemic ewes maintained on a Cu-deficient diet and alleviated hypocupraemia for 111 days when the diet was supplemented with molybdenum (Mo) and sulphur (S), and 301 days when the diet was not so supplemented.