Copper, like iron, is necessary to allow red blood cells to form normally and deficiencies can lead to anaemia. Copper is also important in enzyme systems. Fortunately, nutritional deficiencies in pigs are very rare. It is added to the diet as a growth promoter at levels of up to 175ppm for pigs to 16 weeks of age and 100ppm for pigs over 16 weeks of age (EU legal requirements). It suppresses bacterial growth. There have been occasions in the field where it has been inadvertently and suddenly removed from creep diets. This has been followed by diarrhoea bacterial enteritis and poor growth probably associated with the sudden multiplication of pathogenic bacteria.