Stocking density and stress induction affect production and stress parameters in broiler chickens

The objective of this paper is to analyse the effects of three different stocking densities on the production, stress and fear parameters of female broilers during a 46-day production period. Chickens were randomly distributed among nine floor pens in groups of 30 broilers with different space allowances for each treatment, namely eight, 20 and 30 chicks m-2. Chicken growth rate was monitored from day eleven to 46 and indicators of stress, including haematocrit, heterophil/ lymphocyte ratio and concentrations of plasma corticosterone, as well as tonic immobility, were measured on days 22 and 46. On day 46, the incidence of foot and skin lesions was assessed, and stress was induced to analyse the response of broilers to each stocking density. High stocking densities cause acute stress in broilers; the effects of low and intermediate stocking densities, however, are not so evident, particularly in relation to tonic immobility and response to acute stress. © 2009 Universities Federation for Animal Welfare.