Contentedly pecking seed in the open countryside, free-range hens have carefree lives that their counterparts in battery farms can only dream about, or so it has long been believed.
In fact, caged hens are no more stressed than those that roam free, researchers have discovered.
Scientists measured corticosterone, a hormone produced in response to stress or fear, in eggs from free-range and caged hens. They found that the levels in both were very similar.
Free-range hens suffer stresses that battery hens do not have to deal with, according to Jeff Downing, who led the research at Sydney University. "If they have no cover they are constantly in fear of attack by predators," he explained. "You can see it. A shadow comes over and they are completely startled."
Mr Downing added that free-range hens are prone to manure-borne diseases and parasites, that extreme temperatures are more stressful to hens than the method of their housing, and that caged hens have greater protection from both the elements and predators.
Julia Wrathall, head of the RSPCA's farm animal department, said the research contrasted with a number of other studies that have suggested that caged birds suffer more than free-range hens. "The RSPCA believes, and scientific evidence shows, that battery cages are simply unacceptable because they don't adequately satisfy the hens' basic behavioural and physical needs," she said.
However, a spokesman for the British Egg Information Service, the industry body for egg producers, welcomed the findings, saying that the welfare of hens, however they were kept, was of "paramount importance".
Despite a recent rise in sales of "higher welfare" eggs, around 19 million hens are caged in Britain, accounting for 63 per cent of egg production.
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