Rise of mega farms: how the US model of intensive farming is invading the world

Since the days of the wild west frontier, the popular image of American farming has been of cowboys rounding up steers on wide open ranches, to whoops, whips and hollers. Today, the cowboys on their ranches under wide open skies have been replaced by vast sheds, hulking over the plains, housing tens of thousands of animals each, with the noises and smells spreading far beyond their fences.

The US has led the world in large-scale farming, pioneering the use of intensive livestock rearing in hog farms, cattle sheds and sheep pens. There are now more than 50,000 facilities in the US classified as concentrated animal feeding operations (CAFOs), with another quarter of a million industrial-scale facilities below that threshold.

Around the world, developing countries in particular were quick to catch up. Intensive farming of livestock offers many advantages over traditional open ranges, not least economies of cost and scale, more efficient healthcare for the herds and flocks, and ultimately cheaper food. According to the UN, globally CAFOs account for 72% of poultry, 42% of egg, and 55% of pork production.

In 2000, there were an estimated 15 billion livestock in the world, according to the Worldwatch Institute. By last year, that had risen to about 24 billion, with the majority of eggs, chicken meat and pork produced on intensive farms.