The basic nutrients required are crude protein, metabolizable energy, minerals, vitamins and water.[5] The formulation procedure has both fixed and variable portions.[7] Swine rations are generally based on a ground cereal grain as a carbohydrate source, soybean meal as a protein source, minerals like calcium and phosphorus are added, and vitamins. The feed can be fortified with byproducts of milk, meat by-products, cereal grains; and "specialty products." Antibiotics may also be added to fortify the feed and help the animal’s health and growth.[6]