Beef cattle are raised and fed using a variety of methods, including feedlots, free range, ranching, backgrounding and intensive animal farming. Concentrated Animal Feeding Operations (CAFOs), commonly referred to as factory farms, are commonly used to meet the demand of beef production. CAFOs supply 70.4% of cows in the US market and 99% of all meat in the United States supply. Cattle CAFOs can also be a source of E. coli contamination in the food supply due to the prevalence of manure in CAFOs. These E. coli contaminations include one strain, E. coli O157:H7, which can be toxic to humans, because cattle typically hold this strain in their digestive system. Another consequence of unsanitary conditions created by high-density confinement systems is increased use of antibiotics in order to prevent illness. An analysis of FDA sales data by the Natural Resources Defense Council found 42% of medically important antibiotic use in the U.S. was on cattle, posing concerns about the development of antibiotic resistant bacteria. In 2023 production was forecast to peak by 2035.