The two major products widely used by the United States feed industry are of high biological availability. Periclase products and products made by grinding magnesium by-products such as refractory bricks are available to the feed industry, but are of highly variable quality and biological value. The major use of magnesium oxide is found in feeds and minerals designed to help prevent grass tetany when cattle are on lush spring or fall pastures. Magnesium is required in the diets of all animals for growth and general health. It is specifically required in the diets of ruminant animals to prevent hypomagnesemic tetany.
Magnesium oxide is the major source of magnesium for animal feeds.
Magnesium sulfate is also used, but its use is limited due to its laxative properties.