Copper sulfate (CuSO4 x 5 H2O) has a copper content of 25% and has frequently been used at high levels (125 to 250 ppm Cu) to attain a growth response in weanling and market pigs. The 250 ppm level corresponds to 0.1% copper sulfate in the final diet mixture, which is equivalent to 2 pounds per ton of diet. Although the addition of copper sulfate to swine diets is legal, care should be taken to assure an even distribution of copper in the diet mixture. A dietary copper level of 500 ppm is toxic to swine. An added benefit is often obtained when antibiotics and copper sulfate are used in combination for growth promotion, particularly for weanling pigs.