Confined animal feeding operation or CAFO is typically a large building that houses thousands of animals, typically chicken, pigs, or dairy cows. In many regions of the United States, CAFOs have replaced the traditional and versatile barn in the rural landscape, as many farms have become specialized 'industrial' units closely aligned to large agricultural companies.

While the operations of a CAFO allow for meat to be harvested cheaply by utilizing economies of scale, some argue against CAFOs for at least two reasons.

The first is that CAFOs treat animals inhumanely. The animals are crowded closely together and sometimes are force-fed.

The second argument against CAFOs is that they often lead to very large amounts of manure, which is difficult to dispose of. In small quantities manure is a valuable resource that can be used as a fertilizer. But in large quantities it can be difficult to get rid of. Temporary storage still leaves the problem of the terrible smell.

Chicken CAFOs in Maryland's Eastern Shore have been implicated in the pollution problems of the Chesapeake Bay. The hog farms in North Carolina led to huge water pollution when that state was struck by a hurricane in the late 1990s