Slower growth, indoor environmental enrichment, or covered veranda access: a comparison of three rearing systems for broiler chicken welfare and behavior

The use of slower-growing chicken strains and environmental enrichments are major levers for improving broiler welfare. This study compared the effects of three rearing systems on the welfare and behavior of broiler chickens: intermediate-growing broilers (Redbro) kept in an unenriched environment (“RDB”), fast-growing broilers (Ross 308) kept in a highly enriched and complex indoor environment (“RoE+”), and fast-growing broilers (Ross 308) having access to a 36-m² covered veranda from D14 (“RoCV”). Each of the four 81-m² pens per treatment housed 1,350 birds until they reached a final body weight of 1.9 kg, corresponding to a final indoor stocking density of 30 kg/m². As they aged, the RoCV chickens increasingly went into the covered verandas until an average of 27% of the birds in the verandas was reached on D32. At the same time, RoE+ broilers perched more and more on the enrichments over time. RoE+ birds consumed more water than RoCV chickens from D24 onward, without any difference in feed consumption. RDB and RoCV birds had fewer leg lesions than RoE+ ones, although the litter quality did not differ between the treatments, but RDB birds had better gait scores than either RoE+ or RoCV broilers. More walking, running, foraging, sparring and frolicking behaviors were observed in the covered verandas than in the indoor pens, where resting behavior was more frequently observed. RoE+ birds dustbathed more often than RDB and RoCV chickens. No difference between treatments was found for mortality. Fewer RoCV broilers reached the different steps of the detour test and approached a novel object than RDB and RoE+ broilers. Overall, the three rearing systems compared influenced different aspects of broiler welfare: RDB treatment was associated with better walking ability and fewer occurrences of footpad dermatitis, RoE+ with more comfort behaviors, and RoCV with more active behaviors and improved footpad condition.