Battery cages around Australia hold 11 million egg laying fowls, while 788 million meat chickens (broilers) are in "factory" farms in Australia. No other animal is used on this scale for protein production, but what is the price these intelligent, social and curious animals pay on the production line?

Retail giant Woolworths and goliath fast food chain McDonald's have flagged to industry that the institutionalised cruelty of intensively farming hens will no longer be tolerated. It has been a long time coming. Woolworths was first approached by Animal Liberation in 1993 to consider phasing out the sale of cage eggs. But tenacity is the name of the game in the animal protection movement and last week that bore fruit.

The assault and battery for the commercial caged hen begins a day after hatching. The front of her beak is cut off with a hot wire guillotine to stop the worst injuries caused by later cannibalism in the cages. Ironically, the cannibalism is caused by the distress from living in the barren cage. She will be cramped in a cage with one to five others, standing on thin sloping wire, each with space less than an A4 sheet of paper for their entire lives.

Over 12 to 18 months their bones become weak from osteoporosis caused by no exercise – not able to perch, walk or dust bathe. The only day they see the sky and feel the sun on their back is on the way to slaughter but more than half will be in acute pain from broken and fractured bones. "A good measure of the savagery of the system", as stated by Magistrate Michael Ward when activists were defending a trespass to assist battery hens in 1996.

It was during the first prosecution of a battery hen farmer, in Tasmania in 1992, by the infamous Pam Clarke that Magistrate Philip Wright stated "the suffering of the hens was ongoing, continuous and without relief"'.

Governments across Australia go out of their way to keep animal welfare, particularly for farm animals, at arm's length by throwing a few dollars at an under-resourced charity to administer the Animal Protection Act, at the same time insisting on the portfolio of animal welfare remaining in the Department of Primary Industries – the very government body that protects corporate farming. How has a little hen to have any chance under that colossus?

The European Union will ban the barren cage in 2012 – many EU countries already have. Californian voters overwhelmingly voted to abolish the cage and have sent the message across the US. It begs belief why, in one of the wealthiest first world countries, that the Australian government is too mean to let hens have a run around.

The "broiler" meat chicken is now the cheapest meat to buy. Once the "treat" of the Sunday roast dinner it is now the common lunch fast food burger or wrap. But if Ingham's or Bartter Steggles were to have an "open inspection" day for consumers to have a look through their sheds – and make it the day before the birds are taken to slaughter – they would be in for a shock.

Meat chickens are pushed so hard by genetics and feed conversion (and sometimes antibiotics) to grow so fast that they are the weight of a full adult after a mere 42 days instead of the usual three months. Some still have blue eyes – the eye colour of baby chicks. But they are cripples and walk like little Frankensteins. Severe leg abnormalities, dislocated hips and hock burns (from the ammonia) are common place. But if they are breathing when they arrive at the abattoir, the farmer gets the 50-70 cents for the animal.

Interestingly, the chicken grower (farmer) will tell you they are exploited almost as much as the chickens. The corporate industry company owns the birds and the feed. The grower owns the sheds. Everyone is under the thumb.

But are these animals beginning to bite back?

The epidemic most feared by the World Health Organisation derives from the very animal we most exploit – the bird. Bird flu – H5N1 only has to go through a few more mutations to be able to become airborne. Interestingly it has learnt how to tear our lungs apart by learning mammalian respiratory information from pigs – the second most exploited animal in the world next to cattle.
The WHO has openly stated that the intensive farming of poultry poses one of the greatest opportunities for bird flu to mutate. A battery hen shed or broiler meat chicken facility are ripe petri dishes for viruses to flourish. Tens of thousands of blood-rich little lungs in which to go forth and multiply. This is serious stuff. Of the people who have been infected by H5N1, through fluid to fluid contact, 53 per cent died.

Maybe, in an uncanny way, the retail and fast food giants that are beginning to turn around the industrialisation of farming animals will not only help the animals but save us from a sinister outcome — something neither the intensive industry or its gatekeeper, the government, has been willing to do.

It is heartening to realise that it is the average, reasonable person (and consumer) who refuses to tolerate animal abuse that is really driving the revolution for farmed animals.

Mark Pearson is executive director of Animal Liberation.