Dr Martin Potter, head of the RSPCA's farm animals department, gave his support to the report drawn up by Dr Mike Baxter, a member of the Government's Farm Animal Welfare Council.
The study, published in Veterinary Record, contradicts a document by the Commons Select Committee on Agriculture last month, which said battery farming should not be abandoned as fat hens laying eggs could not be under stress.
However, Dr Baxter said hens being packed tightly together, eight rows high in cages less than 18in high, inevitably led to aggression and feather-pecking. He concludes: 'The evidence shows beyond all reasonable doubt that keeping hens in cages is extremely distressing in many different ways.'
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