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.

Le regole dell’allevamento biologico di polli da carne, rendono obbligatoria la presenza ed accessibilità ad aree esterne in cui gli animali possano esprimere i loro comportamenti naturali tra cui l’attitudine al foraggiamento e all’esplorazione dello spazio esterno. Tuttavia si osserva che l’uso dell’area esterna ha un’alta variabilità anche tra individui di uno stesso gruppo. Nel progetto PPILOW si è ritenuto necessario comprendere meglio i fattori individuali e i potenziali predittori correlati all’uso dell’area esterna.

I risultati da un lato confermano che l’uso dell’area esterna è  un tratto di personalità rilevabile in tutti i quattro ceppi studiati, differisce tra gli individui ma presenta una coerenza nel corso del tempo nel medesimo individuo. D’altro canto, la motivazione sociale e l’audacia sembrano essere tratti di personalità riscontrabili solo in alcuni ceppi.

Conducendo sia test comportamentali individuali sia osservazioni su comportamenti precoci dei pulcini prima dell’accesso all’area esterna è stato osservato che :

• vi sono differenze nei comportamenti precoci a seconda dei ceppi e poche correlazioni significative al successivo utilizzo dell’area esterna;
• sono rilevabili correlazioni positive nell’attitudine al foraggiamento (significative o solo tendenziali) in tre ceppi;
• in nessun ceppo è stato possibile correlare i comportamenti precoci (predittivi) al successivo uso dell’area esterna.

Pertanto, il comportamento precoce non ha predetto l’uso dell’areale esterno mentre l’attitudine al foraggiamento merita ulteriori indagini e approfondimenti.