Free-range use and behavior of slow-growing broiler chickens: effects of shelter type, enrichment, age and weather conditions

Increased free-range use by slow-growing broiler chickens could benet their welfare. €is study aimed to assess the e�ects of enrichment early in life, shelter type (articial or natural), weather conditions and age on broilers’ free-range use. €ree production rounds (R) were performed, with 440 Sasso chickens each. Birds were housed indoors in 4 groups of 110 animals from d0-25, during which 2 groups per round received environmental enrichment (hay bales, strings, grain, mealworms). At d25, birds were moved to 4 mobile houses on a 1 ha eld. From d28-70, birds had access to both grassland with articial shelter (A-frames; AS) and short rotation coppice (SRC). SRC consisted of densely planted willows (15,000 trees/ha). Free-range use was observed 3 times daily on 15, 21 and 18 days in R1, R2, and R3, respectively. €e number of animals outside, their location (AS; SRC) and distance from the house (0-2 m; 2-5 m; >5 m) were recorded. In R2 and R3, behavior of the outside chickens was also recorded. Weather conditions were recorded every 15 min. Data were analyzed using a GLM Poisson regression model, with a rst-order autoregressive covariance-structure to correct for multiple observations over time within the same house. For multiple comparisons, p-values were corrected using the Tukey-Kramer method. On average, 26% of the birds were outside. Early-life enrichment tended to have a small positive e�ect on free-range use (0.4% more birds outside; P=0.052). At all distances, more birds were in SRC compared to AS (all P<0.001). In AS more birds were at 0-2 m than at 2-5 m or 5 m from the house (all P<0.005). In SRC more birds were at 0-2 m and 2-5 m than at >5 m from the house (all P<0.001). Freerange use increased with age, particularly in areas further from the house (P<0.001). In AS, rainfall and low solar radiation were related to more birds outside, while the opposite was true in SRC (P<0.001). Fewer birds were outside with increasing wind speed (both AS and SRC; P=0.049). A higher percentage of chickens was observed to forage in AS compared to SRC (50 vs 28%; P<0.001). €e opposite was true for standing (6 vs 9%; P<0.001) and sitting, but for the latter the di�erence tended to decrease with distance from the house (P=0.065). We conclude that: (1) early-life enrichment had no profound e�ect on free-range use in broilers; (2) SRC was preferred over AS, suggesting this shelter was more suitable and attractive; and (3) behavior was related to shelter type.