Stocking density in broiler housing is one of the most well-researched and important welfare determinants in poultry production.
Broiler stocking density affects welfare through multiple pathways simultaneously. At high densities, competition for food, water and resting space increases stress and reduces the ability of subordinate birds to access resources. Ammonia from litter accumulates faster at higher densities causing respiratory irritation and eye problems. Footpad dermatitis from wet litter increases with density. Movement is restricted reducing the activity that supports leg health. Lower density systems allow more normal movement and social behaviour while improving air quality and litter condition. The relationship between density and welfare is among the most clearly established in farm animal research.