How do you like your eggs? Read our undercover investigation into Britain's battery farming

The birds that spend their lives standing on wire mesh without enough space to turn around. Yet three out of five eggs we eat come from farms like these. Martin Hickman reports

Undercover investigators have filmed the ugly reality of egg production at a battery chicken farm supplying the biggest egg producer in the UK.

Viewed from the air, Holsworthy Beacon Farm takes its place in an idyllic rural scene. But in its sheds, chickens are crammed five to a cage, stacked in rows from floor to ceiling.

Compassion in World Farming (CIWF), which visited the farm in conjunction with The Independent on Sunday, found hens unable to spread their wings fully, nest, or exhibit other natural behaviour. Some had large bare patches where they had lost their feathers.

"As soon as you come in from the fresh air, the smell hits you straight away," said a CIWF investigator, describing the mixture of animal waste, ammonia and disinfectant emanating from the cages. "If a bird is in the way, the others will clamber over them... It's a fight for food if they all want to feed at the same time."

The family-owned farm on Devon's Exmoor produces more than 100 million eggs a year for Noble Foods, which supplies 70 per cent of the UK egg market.

Conditions at Holsworthy Farm are thought to be legal, and "representative" of conditions at battery chicken plants across the country. About 55 per cent of eggs consumed in the UK are battery-farmed. Although free-range sales are rising – hitting 51 per cent of retail sales value earlier this year – almost all processed and restaurant foods are made with battery eggs. Only one in three eggs is free-range.

Hugh Fearnley-Whittingstall, the TV chef who exposed the reality of intensive chicken meat production, said: "I have the same reservations about the battery cage system as about intensive broiler houses for meat birds. I am at least as concerned, if not more so.

"A lot of people now choose to buy free-range eggs and they assume the battle on eggs is being won. But it hasn't, because 60 per cent of the eggs we eat are battery farmed."

The system of barren battery cages is so undesirable for animal welfare that the European Union banned it in 1999. After years of delays caused by industry lobbying, Britain will implement the ban in 2012, replacing barren cages with slightly larger "enriched" cages with perches.

"Caged birds have little space to move," said Dr Lesley Lambert, CIWF director of research. "Throughout their adult life they cannot exercise. They will struggle even to fully stretch their wings. The amount of space they have in a barren battery cage is less than a sheet of A4 paper per hen. They spend their whole lives standing on a wire mesh."

The Government announced the ban on battery farming as a Channel 4 series brought the unpleasant reality of intensive poultry production into millions of homes night after night in the series Hugh's Chicken Run. Sales of free-range chicken leaped after the show revealed how intensively reared "broiler" birds developed leg sores from walking in urine-covered sawdust in cramped, windowless sheds.

Animal welfare campaigners hope the same commercial clout will apply enough pressure to end the farming of caged birds.

"The reason you have such massive feather loss in battery caged hens is either because other birds will peck out their feathers or they spend much of their time pressed up against the wires of the cage," said Dr Lambert. "The system is designed for maximum production, without any reference to animal welfare. They never ever go outdoors, have natural light, or exercise."

It is not clear to whom the eggs produced at Holsworthy Farm are ultimately supplied, because neither the farm nor Noble Foods will divulge the information. Noble, which has annual sales of more than £400m, owns a factory over the road from Holsworthy Farm, which packages its Big and Fresh brand. Big and Fresh eggs are sold by Tesco and Somerfield.

Tesco said in a statement that it did not stock eggs from Holsworthy. Somerfield said there was "no evidence" that eggs from Holsworthy were supplied to its stores. But, it said: "We will fully investigate these allegations and take whatever action is appropriate to satisfy consumers."

Noble Foods, which describes itself as the "progressive face of the UK egg industry", insisted that the farm had high welfare standards. "We conduct regular audits of all our farms, and at the last audit of this farm we were satisfied that the birds were well looked after and the farm met the required standards," said Andrew Joret, the company's technical director.

Welfare campaigners urge the public and food manufacturers to insist on free-range eggs. CIWF will present its Good Egg awards on Tuesday to companies such as Hellmann's that have switched to free-range.

"In food manufacture, the eggs are in effect invisible," said Mr Fearnley-Whittingstall. "In the end, if we want to change the system, just choosing fresh free-range eggs isn't enough."

We demand food companies:

* End the sale or use of eggs from hens in battery cages, or even in the roomier "enriched" cages, by 2012

* Introduce clear and unquestionable minimum standards that make it simple for consumers – sell or use only free-range eggs

* Stop charging higher premiums on free-range eggs without compromising on a fair price for farmers

* Use clear and honest labelling that truly represents how whole eggs and egg ingredients are produced

* Use no misleading images or wording – for example, "farm fresh"

* Use no illegible or hidden production information

* Label the method of production on all products that contain egg

* Encourage and support farmers to develop free-range or barn production of eggs

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