First evaluation framework based on the one welfare concept in extensive broiler rearing systems.

The One Welfare concept has emerged to counter the traditional separation of human well-being, environmental sustainability, and animal welfare, emphasizing their interdependence within specific ecological and socio-technical contexts. Despite its promise, the practical operationalization of One Welfare as an evaluation framework remains limited. This study proposes and tests an operational One Welfare approach (OWA) for extensive broiler rearing systems (ERS), explicitly promoting direct and indirect links between animal and human welfare and situating them within the environmental performance. Although ERS constitute a minor share of EU broiler output (≈ 5%), interest in and adoption of ERS have grown markedly over the past two decades, underscoring the need for assessment tools that capture their broader contributions. Conventional evaluation methodologies, designed around intensive systems, tend to prioritize yield, short-term efficiency, and market indicators, and may therefore underrepresent the ecological, social, and welfare advantages achievable in diversified, outdoor systems. We implemented a multicriteria decision analysis (MCDA) using the One Welfare Approach to synthesize indicators across the animal welfare, environmental, economic, and social pillars in a broiler case study. The framework proved feasible despite data constraints (limited availability and some invariant parameters typical of ERS, and its outputs aligned with published evidence on slow-growing genotypes in outdoor systems, supporting construct validity. The Key results showed that: (1) Environmental enrichment with olive trees improved OWA performance: all enriched options outperformed their non-enriched counterparts, showing that tree/shrub cover increases outdoor use, reduces predation and fear, and improves integument condition in free-range birds. (2) Under enrichment, RJ_E ranked first overall. Flow decomposition indicated that CB_E exhibited higher positive flow (Phi+), but RJ_E had a lower negative flow (Phi⁻); given the non-compensatory OWA stance, suppressing negatives proved more decisive than marginal gains in positives. A weight-sensitivity check showed ranking stability across pillars, with limited shifts confined to the Economic pillar, where criterion values were tightly clustered. Taken together, these findings indicate that One Welfare assessment can capture trade-offs and synergies that conventional metrics overlook, offering actionable guidance for extensive organic broiler systems. The approach is compatible with prevailing outcome-based welfare assessment practice. It can be simplified into a transparent index for on-farm self-assessment and external communication, provided that its governance and evidence base meet current best practice expectations.