Soybean meal is the material remaining after solvent extraction of oil from soybean flakes, with a 50% soy protein content. The meal is 'toasted' (a misnomer because the heat treatment is with moist steam) and ground in a hammer mill. Soybean meal is an essential element of growing farm animals such as poultry and swine on an industrial scale that began in the 1930s; and more recently the aquaculture. Ninety-eight percent of the U.S. soybean crop is used for livestock feed. Soybean meal is also used in lower-end dog foods.