Primary copper deficiency arises from a direct shortage of copper in the diet whereas secondary copper deficiency results from the antagonistic effects of elements such as molybdenum and sulphur upon absorption. Copasure 24g is an effective long acting supplement in both cases. The severity of copper deficiency, whether of primary or secondary origin, varies greatly from farm to farm. On most copper deficient sites one dose of Copasure 24g, given to grazing cattle at turnout, will maintain normocupraemia over the grazing season and leave animals with a substantial liver copper reserve at housing. It is impossible, however, to cover the full range of deficiency states with a simple dosing regime. Veterinary surgeons may need to adapt their advice to suit local conditions. The oral administration of copper obviates the risk of local lesions often associated with copper injections, as well as the risk of toxicity associated with too rapid a rise in blood copper concentration.