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International audience; Free-range systems provide an outdoor range for broilers to give them the possibility to express a higher frequency and a wider range of behaviours, such as exploration, compared with those raised indoors. Greater variability in outdoor range use between individuals of the same flock is often reported. Individual variation in range use may result from differences in early-life behaviour or genetic background. Understanding how earlylife behaviour influences range use may provide opportunities to enhance and predict range use. Previous studies have shown that range use could be influenced by the animal’s personality traits such as social motivation, boldness and foraging motivation. Therefore, this study investigated personality traits in several broiler strains, namely Hubbard JA757, Hubbard S757N, White Bresse and a dual-purpose strain; we examined the latter as it represents a potential solution to the ban of 1-day-old chick culling. The present study also investigated early-life behaviours, before range access, of range use to identify and assess the stability of these early-life indicators among the four broiler strains. For that purpose, we recorded the behaviour and range use of 100 male chickens per strain, both in the barn and during individual tests, before and after range access. We examined which behaviours were time consistent, whether early-life behaviours were influenced by genetic variation and whether early-life behavioural indicators predicted range use regardless of genetic variation. There was a significant (p < 0.001) difference between strains in several early-life behaviours, including the time spent resting or standing. Range use was time consistent regardless of the strain as our range use indicator followed a high-quality linear regression model (R2 > 0.7) for 82–99% of the individuals depending on their strain. Besides, time consistency of social motivation and boldness seemed to depend on the strain. Even though foraging showed low (rho = 0.2–0.4) positive correlations with range use in three of the four studied strains, there were no significant and strong correlations in the four studied strains between early-life behavioural indicators and range use. In conclusion, our results show that the link between chick behaviour (before range access) and range use can be modulated by the bird’s strain. It is crucial to consider all these different factors to better understand how range use varies within and between flocks.

International audience; Free-range broiler chickens usually show an uneven spatial utilization of an outdoor range. Due to behavioral and cognitive between-individual differences, some animals may be driven to associate food and conspecifics more strongly to the barn, causing them to be less prone to explore the range. In this study, we aimed to understand how broiler chickens with different ranging levels (low- and high-ranging chickens) would behave under conditioned place preference (CPP) test situations. We used two cohorts conditioned to two natural rewarding stimuli: food and social companions. In a two-chambered apparatus, one cohort (n = 31, 16 high-ranging, and 15 low-ranging chickens) was conditioned to one chamber that always contained a cup with a food reward (mealworms), while the cup in the other chamber was always empty. The same design was also used with the second cohort (n = 31, 15 high-ranging and 16 low-ranging chickens), although instead of food, the reward was the physical presence of two conspecifics. During the testing trials, the animals had access to both empty chambers, and the time spent in each chamber was quantified. For the first day of the food CPP test, both the high- and low-ranging chickens spent significantly more time in the conditioned chamber, where they had previously found mealworms. During the following extinction days, the animals showed a gradual loss of their learned preference, increasing their immobility in the apparatus. High-ranging chickens were more immobile than low-ranging chickens, however, as their number of trials without moving was significantly higher. Unexpectedly, during the first day of the social CPP test, only high-ranging chickens showed a place preference. An overall place preference was observed only on the second day, with no chamber preference during the extinction days. Our results suggest that whether and how a stimulus-reward association occurs for free-range chickens may also be dependent on individual differences and the nature of the reward (food or social). Since associative learning occurs on a daily basis for farmed animals and the way individuals learn or value the reward varies, this research advanced our knowledge of animal behavior and individual cognitive differences that can be highly beneficial in improving animals' living conditions; this new understanding will allow for a more individualized approach to rearing broiler chickens in outdoor systems.