Royal Society Open Science

Oliver Martinic, Luisa Magrin, Valentina Caldart, Rhea Harrison, Margaret Hegwood, Flaviana Gottardo, Harriet Bartlett; The environmental cost of welfare-driven policy changes in UK egg production. R. Soc. Open Sci. 1 July 2026; 13 (7): rsos251830. https://doi.org/10.1098/rsos.251830

Public concern over animal welfare in intensive farming systems such as egg production is rising. Meeting future demand for eggs presents both welfare and environmental challenges. Cage-use regulations could reshape farm practices and environmental outcomes, while necessitating larger hen populations, potentially increasing overall mortality and the number of animals slaughtered. National-scale assessments of such welfare-driven changes remain limited. We used UK egg production data to evaluate the environmental and welfare implications of transitions between furnished cage, barn, free-range and organic systems. Eight national-scale scenarios were modelled, each with constant egg output but differing system distributions: ‘business-as-usual’ (cage, barn, free-range non-organic and organic systems), ‘cage-free: free-range’ with production shifted from cages to free-range system (comprising barn, free-range non-organic and organic systems), ‘cage-free: barn’ with production shifted from cages to barn system (comprising barn, free-range non-organic and organic systems), fully battery cage, fully furnished cage, fully barn, fully free-range non-organic, and fully free-range organic. Life cycle assessment methodology was used to estimate environmental impacts, including global warming potential, eutrophication potential, acidification potential and land occupation, using data from previously published studies of UK production systems. Cage systems had the lowest mortality rates and numbers of hens slaughtered, as well as the lowest global warming potential, eutrophication potential, acidification potential and land occupation. The business-as-usual scenario had lower global warming potential and acidification potential, while eutrophication potential and land occupation were lower in cage and barn systems. The business-as-usual scenario required fewer hens and had lower mortality than the non-cage scenarios, except for barn and cage systems. These results highlight the need to integrate environmental and welfare outcomes when guiding future transitions toward non-cage egg production.