Most food has its origin in plants. Some food is obtained directly from plants; but even animals that are used as food sources are raised by feeding them food derived from plants. Cereal grain is a staple food that provides more food energy worldwide than any other type of crop.[3] Corn (maize), wheat, and rice – in all of their varieties – account for 87% of all grain production worldwide.[4][5][6] Most of the grain that is produced worldwide is fed to livestock.