Effects of Environmental Enrichment on Leg Health and Locomotor Traits of Broiler Chickens Fed Antibiotic or Multi-Strain Probiotic Performance Enhancers.

Commercial broiler production faces the challenge of optimizing animal welfare and rapid genetic gains in growth rate, with locomotor disorders and footpad lesions remaining important limiting factors. Antibiotic growth promoters and probiotics are dietary strategies for modulating gut health, whereas environmental enrichment promotes physical development. This study evaluated the effects of dietary additives and environmental enrichment on welfare indicators in broiler chickens. A total of 1440 male chicks were assigned to a completely randomized 3 × 2 factorial design (control, antibiotic, and probiotic diets, with or without environmental enrichment), with eight replicates per treatment. Environmental enrichment consisted of a plastic ramp and rotating objects (mirrors, hay, chains, and balls). Locomotor traits, including gait score, pododermatitis, angular deformities, and latency to lie, were assessed. A significant interaction between dietary additives and environmental enrichment was observed for femoral degeneration, with probiotic-fed birds under enriched conditions showing the lowest degeneration scores. Probiotics also improved gait score at 36 days, whereas both probiotics and antibiotics reduced pododermatitis severity. No effects were detected on tibial dyschondroplasia, spondylolisthesis, latency to lie, angular deformities, dorsocranial myopathy, or bone strength. The combination of probiotics and environmental enrichment positively influenced selected locomotor welfare indicators, whereas both dietary additives reduced pododermatitis without affecting major skeletal disorders.