Effects of environmental enrichment on health and bone characteristics of fast growing broiler chickens

Abstract Providing environmental enrichment for broilers is a potential strategy to increase welfare, activity, and health. The aim of this study was to evaluate the effect of environmental enrichment on health and leg bone characteristics of broilers. One control and 8 types of enrichment were included: 2 distances between food and water (7 and 3.5 m), roughage, vertical panels, straw bales, 2 platforms (30 and 5 cm), and a lowered stocking density (34 kg/m2). Birds were kept according to conventional Danish guidelines. The study included 58 pens with approximately 500 birds each. On day 35 of age, 25 birds per pen were killed and included in a postmortem analysis of wooden breast, body condition scores, pathological conditions (femoral head necrosis, arthritis, tenosynovitis, fractures, tibial dyschondroplasia, and twisted tibiotarsus), muscle width of the lower leg, and tibiotarsus properties (bone strength, weight, length, and proximal diameter, middle diameter, and distal diameter). It was predicted that environmental enrichment would have a positive effect on pathology with the exceptions that environmental enrichment that increased activity would pose a risk factor for wooden breast development, and straw bales would be a risk factor for bacterial infections (arthritis, tenosynovitis, and femoral head necrosis). Furthermore, it was hypothesized that enriched groups would have increased muscle width, bone strength, and dimensions of the tibiotarsus. Broilers with 7 m between food and water had a longer distal diameter of the tibiotarsus than those with straw bales (P = 0.04). The birds provided with vertical panels had wider leg muscle than the treatments with roughage (P = 0.045), 3.5 m distance (P = 0.049), and straw bales (P = 0.044). No effects were found for the remaining outcomes. These results suggest that provision of vertical panels and increased distance between resources can result in larger muscle and bone dimension, possibly having a positive effect on leg health. Furthermore, the provision of environmental enrichment does not appear to be a risk factor for wooden breast or bacterial infection.