Enhancing welfare in commercially hatched chicks through naturalistic environmental enrichment

Laying hen chicks hatched in commercial hatcheries experience an industrialized process that induces long-term negative welfare effects. The static and homogenous industrial rearing environments contrast with the natural environment of fowl. Introducing environmental complexity has been shown to improve coping abilities, spatial learning, and foster positive affective states. This study aimed to assess if enriching the early environment of commercially hatched chicks could buffer hatchery stress. A total of 58 chicks were hatched at a commercial hatchery and randomly assigned to control (CC) or enriched (EC) pens. Beyond the standard conditions, the EC group received additional UVA/UVB light, peat, fake grass and plants, and a daily scattering of muesli and mealworms. After 4.5 weeks, chicks underwent behavioural, cognitive, and HPA-reactivity tests. In a cognitive judgement bias test, EC exhibited a more positive bias and in a spatial memory test they demonstrated shorter completion latencies and fewer immediate errors compared to CC. Although no differences were found in a novel object test, CC displayed higher general activity behaviours, whereas EC engaged in more comfort behaviours during an open field test. Despite higher baseline and post-restraint corticosterone levels in EC, both groups showed similar corticosterone reactions to a brief restraint. The higher basal levels in EC are probably related to higher activity level as a result of the enrichment. Lastly, EC had significantly fewer fault bars on their R1 feathers. In conclusion, enriching the rearing environment of commercially hatched chicks with naturalistic elements improves welfare by promoting positive affective states, enhancing exploration, and moderating acute stress levels. Moreover, by doing so, it could mitigate stressful experiences commonly incurred at commercial settings. • Environmental enrichment was offered chicks from commercial hatcheries. • The enrichment consisted of naturalistic items including UVA/UVB light. • Enriched chicks had a more positive cognitive judgement bias. • Enriched chicks had fewer feather fault bars. • Naturalistic enrichment can possibly mitigate early stressful experiences.