NINETY PER CENT of battery-reared broiler chickens cannot walk normally and 26 per cent probably suffer chronic pain and discomfort through leg weakness, according to a study by scientists at the University of Bristol.
Leg weakness means birds cannot walk or forage for food easily and affects four of the five fundamental freedoms which the Farm Animal Welfare Council says farmed animals should enjoy. Its incidence is increasing and the authors say the figures probably understimate the true picture, since many birds with leg problems die or are put down.
The study, reported in the current issue of The Veterinary Record, says that leg weakness, common among cows, pigs and turkeys, is both an economic and a 'major welfare' problem among broiler chickens. Because of the high densities in broiler houses, disabled birds cannot compete for food and could suffer injury, malnutrition and dehydration.
Broilers reared in 'commercial' free-range operations showed less leg weakness - only 5 per cent were likely to be in chronic pain - but the authors were surprised that they did not fare better.
Weakness in battery flocks is extensive despite the fact that poultry companies selected breeds without leg deformities. However, the 'overzealous' selection of birds to achieve fast weight gain could encourage strains more prone to leg weakness, the authors add.
If the figures were true for the whole UK broiler flock, it would mean that 130 million birds would suffer chronic pain and 30 million would be so badly affected that, if they were cattle, they would be destroyed.