A study conducted by researchers at the University of Oxford has found that organic free-range egg production has the greatest environmental impact compared to other systems, including caged, barn, and conventional free-range hens. The research, published in the journal Royal Society Open Science, indicates that shifting the entire British egg industry to organic free-range methods could lead to a 60% increase in carbon emissions and nearly double the land required for production.

The study evaluated the environmental footprint of four egg production systems, assuming equal egg output. Organic free-range hens, which are allowed outdoor access and fed organic feed, performed the worst due to lower productivity, higher feed consumption per egg, and reliance on organic crops that yield less compared to conventional feed crops. This led to increased waste production with a higher risk of river pollution.

Lead author Oliver Martinic noted that while the demand for free-range eggs is driven by concerns for animal welfare, differences in production efficiency may result in unintended environmental consequences. Hens in caged systems tend to consume less feed while maintaining egg output, thus requiring fewer resources and generating a smaller environmental footprint.

The researchers also highlighted higher mortality rates among hens in free-range systems, citing risks such as disease exposure, predators, injuries, and feather-pecking. However, they emphasized that mortality rates provide only a partial measure of animal welfare and do not account for benefits such as increased freedom of movement.

Harriet Bartlett, a research associate at Oxford’s Smith School of Enterprise and the Environment, stressed that the findings are not an endorsement of returning to caged methods, which have been criticized for restricting natural hen behaviors. Instead, the study aims to inform both producers and consumers about the complex trade-offs between animal welfare and environmental impact.

The analysis was based on farming data from 2009 and 2010, which the authors acknowledged as a limitation, given possible improvements in farming practices since then. They stated, however, that this represented the most comprehensive data set available for direct system comparisons.

The researchers concluded that no current egg production system performs optimally across all environmental and welfare criteria. They suggested the development of cage-free systems that combine high welfare standards with advances in breeding, nutrition, feed efficiency, and farm management to mitigate environmental impacts while supporting animal well-being.