The effect of stocking density on the welfare and behaviour of broiler chickens reared commercially

An experiment was conducted to compare the effect of two levels of house st ocking density (34kg m(-2) and 40kg m(-2)) on broiler welfare and behaviour . The trial monitored 121 900 birds housed in eight flocks under commercial conditions and used a range of behavioural and productivity measures to as sess welfare. At the higher stocking density: i) the daily mortality was greater for part of the rearing period; ii) the incidence of leg problems, contact dermatit is and carcase bruising increased; iii) the birds' resting behaviour was in creasingly disturbed; iv) locomotion and ground pecking decreased; and v) l ying and preening patterns were affected, probably due to increased disrupt ion by other birds. Aspects of welfare were adversely affected at the higher stocking density. Further research is required to determine how stocking density affects welf are under different commercial conditions.