Start on the Right Foot: Choice in a Complex Early Environment Boosts Coping Abilities in the Domestic Fowl Chick

Abstract Early experience of a complex environment can improve biologically relevant traits related to coping abilities. However, the mechanisms underlying these positive effects are not well explored. We hypothesised that the possibility to express a choice, leading to increased control over the environment, could play an important role. In a balanced design, laying hen hatchlings were reared either in a ‘No-Choice’ environment (single litter and perch type) or a ‘Choice’ environment (four different litter and perch types). Immunological and behavioural indicators of birds’ coping abilities were explored at three weeks of age. Chicks from Choice environments had higher natural antibody titres, lower H/L ratios, required more attempts for tonic immobility induction and were more successful gaining novel food rewards in a repeated challenge test. Results imply that their improved natural immune response better prepared Choice chicks for coping with pathogenic challenges, that they experienced less chronic stress and were less fearful. To conclude, the increased potential for control and stimulation arising from making decisions in an early complex environment seemed to better prepare birds for a variety of challenges to come, boosting their adaptive capacities and their ability to make the most of opportunities.