Vas, J., BenSassi, N., Vasdal, G. et al. 2023. Better welfare for broiler chickens given more types of environmental enrichments and more space to enjoy them. Applied Animal Behaviour Science 261, 105901.

Providing an increased variety of environmental enrichment options, with sufficient space to use them, could increase the behavioural expression of positive affective states in production animals. The goal of this study was to investigate associations between the number of different environmental enrichment options provided by commercial broiler chicken producers at different stocking densities and behavioural indicators of positive affective states in chickens. Thirty fast-growing commercial broiler chicken flocks with various numbers of environmental enrichment types (range: 0–4; e.g. compressed wood shavings bales, cardboard boxes, plastic crates, peat, perches, windows providing natural light) and space allowances (range: 0.058–0.076 m2/bird) were observed at approximately 28 days of age, when stocking density averaged 23.4 kg/m2. A practical transect sampling method involving 15-s 1–0 scans of successive “patches” along transects between feeders and drinkers and along the wall was used to record spontaneous occurrences of easily detected elements of play (worm-run, play-fight, wing flap, jump, run), inquisitive exploratory behaviour (ground-scratch) and comfort behaviour (vertical wing shake, as a marker of dustbathing) performed by undisturbed chickens. When summed together, these behaviours were performed by an average of 1% of the estimated number of chickens observed during the scans. There were positive associations between environmental complexity (number of environmental enrichment types provided) and the prevalence of play-fighting, ground-scratching, vertical wing shaking, and the sum of all observed behaviours. Farmers providing more types of enrichment also tended to provide more space per bird. After taking the number of enrichment types into account, providing more space per bird was associated with higher levels of jumping, running, and the sum of observed behaviours, though a lower prevalence of vertical wing shaking. In conclusion, an increased diversity of environmental enrichment types in commercial broiler houses was associated with higher expression of behavioural indicators of positive affect including social play, curiosity-driven inquisitive exploration, and comfort behaviour, while higher space allowances facilitated the expression of space-demanding locomotory play.