Not only is animal husbandry the major occupation of nomadic and seminomadic tribes scattered over Iran, but each farming village also keeps flocks that graze on the less productive areas. In 2001 there were 53,900,000 sheep, 25,757,000 goats, 8,500,000 head of cattle, 507,000 water buffalo, 145,600 camels, and 280,000,000 chickens. Cattle are raised as draft animals and for milk and are not fattened for beef. Sheep produce many staple items: milk and butter, animal fat for cooking, meat, wool for carpet making, and skins and hides. Poor weather during the 1970s sharply reduced the domestic flocks, and Iran became an importer of wool. The output of animal products has not kept pace with population growth.