Academics have suggested that shifting to an entirely free-range and organic method of egg production would raise emissions by 60% while almost doubling land occupation.
The study, which compared several possible scenarios for the egg industry – including shifts to barn, free-range, and organic systems while maintaining current egg output – suggests the need for the sector to integrate environmental outcomes when guiding future transitions away from caged egg production.
The feed efficiency trade-off
The authors found that although cage-free systems may align more closely with public concern for hen welfare, they may require larger overall hen populations, which could increase environmental pressures.
They estimate the total impact at 2.3 million tonnes of CO2 equivalent for a fully organic model, compared to 1.4 million tonnes for the present production mix and 1.1 million tonnes if every hen were caged, based on baseline data going back to 2009/2010.
Caged birds convert feed to eggs more efficiently than birds in cage-free systems. Consequently, fewer hens and less feed produce the same volume of eggs – a critical factor given that feed represents the largest component of the industry's environmental footprint.
Report author Dr Harriet Bartlett, senior research associate, Smith School of Enterprise and Environment, Oxford University, said: “Our research highlights the importance of considering animal welfare, environmental impact, and food production together when shaping the future of egg farming. Being aware of these tricky trade-offs will help us make better decisions for both the environment and animal welfare in the future.”
UK market trends shift away from cages
Figures from the British Free Range Egg Producers Association (BFREPA) from July show the organic laying flock standing at 1.7 million birds out of a UK total of 43 million—a share of just under 4% that has remained relatively static in recent years.
However, the broader free-range market has expanded significantly, growing from 70.3% in July 2022 (26 million birds) to 78% (33.5 million birds). Meanwhile, barn-housed birds grew to 2.6 million over the same period.
Conversely, birds housed in cages fell 38.3% over four years, dropping from 8.1 million to 5 million, with caged capacity falling 25.4% in the last 12 months alone. The caged share of birds housed has almost halved from 21.9% to 11.6%, with cage-free production of all types accounting for 88.4% of housed birds in July 2026, up from 78.1% in July 2022.
Holding total egg output constant, as the Oxford study does, means that a fully organic sector would require the organic flock to expand more than 25-fold—and even further once lower productivity rates are factored in.
Industry leaders respond
Lee Holdstock, head of Regulatory and Trade Affairs at Soil Association Certification, noted that while the study has merit, it presents an incomplete picture of environmental impact. A truly sustainable food system must account for biodiversity, soil health, water quality, synthetic inputs, and animal welfare alongside carbon emissions per unit of output, he argued.
Gary Ford, head of strategy and producer engagement at Bfrepa, said members were delivering a transition of out cages and into free-range and barn: “Measuring them against a fully organic scenario that no retailer is asking for and no rearing capacity exists to supply tells consumers very little about the choice on front of the.”
The paper, 'The environmental cost of welfare-driven policy changes in UK egg production', has been published in the journal Royal Society Open Science.
