ABSTRACT
Chickens are the most common farmed animal on solid earth. In 2016, around 50 billion chickens were reared for meat. The history of chicken intensification builds on the importance of two key ingredients – the move of rural people to towns and cities and electricity – enabling increased poultry house size and use of fossil fuel to enable the harvesting and transport of feed from previously unachievable distance. Chickens in most intensive systems live their lives on a bed of litter. The chicken business is now global. Although many companies rear chickens in their own country, the birds are all part of a global bird family linked by a small number of broiler chicken genotypes – the selected lines of chicken genetics which provide the great-grandparent, grandparent, breeder birds and finally the eggs that will hatch out to be the birds that are reared for meat.
