Effects of barrier perches and density on broiler leg health, fear, and performance

Deterioration of footpad and hock condition and increased stress are important welfare concerns in high-density broiler production. It has been argued that environmental enrichment may help address these issues. We hypothesized that increasing environmental complexity by providing access to barrier perches across a range of densities should improve footpad and hock health, reduce leg fluctuating asymmetry (FA), and mitigate fear in broilers without compromising bird performance. In this study, 2,088 one-day-old broiler chicks were randomly assigned to one of the following barrier and density treatment combinations over 4 replications: simple barrier, complex barrier, or no barrier (control) and low (8 birds/m(2)), moderate (13 birds/m(2)), or high (18 birds/m(2)) density. In wk 7, data were collected on average tibia width and length, FA of tibia width and tibia length, footpad and hock lesions, tonic immobility, feed conversion, final BW, and mortalities. Broilers at higher densities had more severe footpad (P < 0.0001) and hock lesions (P < 0.0001). Their tibias were also longer (P < 0.0001) and less symmetric in length (P < 0.05). The tibias of birds in complex barrier pens were more symmetric in length compared with controls (P < 0.05). Barrier treatment had no effect on hock lesions, although there was a trend for simple barriers to reduce the severity of footpad lesions compared with the control treatment (P = 0.089). Birds kept in simple barrier pens were more susceptible to tonic immobility induction (P < 0.05). Final BW, feed conversion, and mortalities were neither affected by stocking density nor by barrier inclusion. In conclusion, this study shows a negative effect of high density on broiler footpad health and FA. Although barrier perches did not appear to reduce fearfulness, the improvement in footpad health suggests that simple barriers may provide key welfare benefits to broiler chickens.