High levels of inorganic sulfate and molybdenum in the diet can increase the copper requirement by two- or threefold. Calves fed exclusive milk diets for long periods may develop copper deficiencies. Copper toxicity levels may be as little as 115 ppm of the total ration for cattle. Sheep, however, are more susceptible to copper poisoning than cattle. A specific requirement for fluoride has not been shown in beef cattle.
Toxic levels are the main concern with fluoride in beef rations.
Rock phosphate that has not been defluorinated often contains 3.5 to 4.0 percent fluoride, which is a toxic level when the rock phosphate is 1 percent of the diet. Fluoride is an accumulative poison and its harmful effect may not be noticed for some time. Toxic levels in the diet affect teeth and bone structure and the use of other nutrients. The entire Great Lakes area and most of the northern section of the United States are subject to an iodine deficiency. Iodine is essential for production of thyroxine, a hormone that regulates metabolic rate.