A few related points
Origins of Factory Farming
Intensive animal production began in the 1930s with America's highly mechanized swine slaughterhouses. Henry Ford even credited the slaughterhouses for giving him the idea to take the swine "disassembly" line idea and put it to work as an assembly line for automobile manufacturing.
In 1950, it took 84 days to produce a 5-pound chicken whereas today it takes just 45 days (hsus, 2006 a).
The downside of IFAP (industrial farm animal production) practices is that they have produced an expanding array of deleterious environmental effects on local and regional water, air, and soil resources. Those effects impose costs on the society at large that are not "internalized" in the price paid at the retail counter for meat, poultry, dairy, or egg products.
Unregulated CAFO (captive animal feeding operation) facilities can have disastrous consequences for the people living and working around them. Rivers used for washing and drinking may be polluted. Workers may be exposed to diseases and other hazards that they neither recognize nor understand because of their limited education.
In IFAP systems, large numbers of animals are raised together, usually in confinement buildings, which may increase the likelihood for health issues with the potential to affect humans, carried either by the animals or the large quantities of animal waste. The ifap facilities are frequently concentrated in areas where they can affect human population centers. Animal waste, which harbors a number of pathogens and chemical contaminants, is usually left untreated or minimally treated, often sprayed on fields as fertilizer, raising the potential for contamination of air, water, and soils.
A single ifap housing 5,000 pigs produces the same volume of raw sewage as a town of 20,000, but the ifap facility does not have a sewage treatment plant.
In addition, intensive confinement systems increase negative stress levels in the animals, posing an ethical dilemma for producers and consumers. This dilemma can be summed up by asking ourselves if we owe the animals in our care a decent life. If the answer is yes, there are standards by which one can measure the quality of that life.
By most measures, confined animal production systems in common use today fall short of current ethical and societal standards