Beef, pork and poultry are no longer luxuries. Mass production means that meat, fish, eggs and milk can be produced more cheaply than ever before. Not only do they often cost less than vegetables but many grow faster too. Chickens in six weeks. Ducks in seven. Piglets can be ready for slaughter at three months, though more usually between eight and ten.
Selective breeding ensures they grow bigger and faster than ever before. And so do fast-fattening diets.
Unnaturally high in calories, protein and fat, the ingredients for farm animal feed are cheap and very different from what the animals would eat in their natural environment.
Ingredients include grains, fish oil, soya and palm kernel oil, a by-product of palm oil. 34% of the world's grain crop is used to feed livestock raised for meat. 70 percent of the world's soya and about one quarter of the global fish catch is processed into meal to feed farm animals. The preparation of land for the production of palm oil has destroyed vast tracts of rainforest, particularly in Indonesia and Malaysia which are the main producers.
In addition to these principal constituents it seems that almost anything goes as long as it is cheap and ensures that animals bulk up in the quickest possible time.
In the UK, before the BSE outbreak, blood used to be processed into bloodmeal, bones into bonemeal and the processed feathers of slaughtered poultry into feather meal. But now (for fear of spreading BSE which was almost certainly caused by feeding contaminated processed animal parts to cattle) the EU has banned their use. Slaughterhouse waste - animal parts like bladders, intestines, udders, heads and fat - is also banned for the same reason. However the ban on feeding hatchery by-products - the culled male chicks from the egg industry, egg shells, dead embryos and infertile eggs - was lifted in 2011 for pigs, fish and poultry. And since June this year this processed waste from pork and poultry can again be fed to fish.
The list seems endless, particularly outside the EU: blood, bones, feathers, animal hair, leather, maggots, whale waste, houseflies, rats (in the Philippines) and tadpoles (in Nigeria) are all processed into meal for feeding farmed animals. Manure is rich in vitamins and minerals; rabbits, cattle, poultry and even bats are good sources.
Farm animals it seems have become receptacles for waste products - and processing waste into feed also helps reduce the very considerable problem of disposal.
But for the animals these feeds are far from natural. Fed like this they put on more weight than their legs can comfortably carry. On slatted floors the feet of pigs and cattle are prone to crack - a route for infection and a cause of lameness. Heavy poultry are easily knocked over or else collapse when their legs give out. Unable to get up ammonia burns their skin. Some get trodden down; others are cannibalised even before they die. Forced growth leads to obesity-related diseases like fatty liver and kidney syndrome. Hearts become enlarged and lungs congested. Heart failure is a common cause of death.
This feed is in pellet form and it lacks the bulk of a natural diet that would curb hunger. As a result hungry and bored piglets bite each other - while those that have straw to bulk out their diets are always less aggressive. The same goes for battery hens: if fibre is added to their diet (which is not always the case) they peck each other less.
Indigestion is another side effect of an unnatural diet. Calves and piglets weaned too soon and fed poor quality 'milk replacers' containing fish and palm oil often become ill with diarrhoea which is a major cause of mortality.
In industrial scale farming systems animals' lives are far from natural. All, it seems, are sick. Small farmers who rear their animals in a natural way call in vets to treat them when they are ill; meat industrialists do not. This business is all about providing food that is as cheap as it can possibly be.
Keeping prices down means the industry cannot afford to care about the animals. Any meaningful welfare is impossible and the cost is paid by the animals: factory farming's victims. Lame, sick, weak and afraid, their entire lives are, in effect, torture. As long as we keep buying their produce we are supporting the factory farming industries and all their inherent cruelty.