Organic and free-range eggs are twice as bad for the environment than eggs from chickens kept in cages, a new study has found.
Shifting to an entirely organic free-range method of egg production would raise carbon emissions by 60 per cent while almost doubling land occupation for the birds, according to researchers at the University of Oxford.
Only producing organic free-range eggs would lead to greenhouse gas emissions equivalent to 2,316,000 tonnes of CO2. In comparison, only producing chicken eggs using caged birds would emit 1,184,000 tonnes of CO2.
That is because although organic free-range is preferable for animal welfare, more chickens are needed to produce the same amount of eggs as caged chickens are more efficient at laying.
Organic free-range is also worse for water pollution and land use, the researchers warn.
“Our research highlights the importance of considering animal welfare, environmental impact and food production together when shaping the future of egg farming,” says author Dr Harriet Bartlett, at the Smith School of Enterprise and the Environment, University of Oxford.
“Being aware of these tricky trade-offs will help us make better decisions for the environment and animal welfare in the future,” she added.
For the study, published in the journal Royal Society Open Science, Dr Bartlett and colleagues examined data from UK poultry farms and calculated the environmental impacts of each, such as greenhouse gas emissions, land used and other types of pollution, such as water pollution.
Researchers also looked at animal welfare, including death rates and the number of hens needed to produce a certain amount of eggs.
The study revealed chicken mortality was also highest in organic free-range farming. Greater exposure to disease, injuries and feather pecking, could all be contributing to the high death rate, study authors suggest.
However, the study used data collected between 2009 and 2010 and the authors acknowledged that progress has been made in the 16 years since.
The global food supply chain is responsible for 26 per cent of human-caused greenhouse gas emissions. It’s also responsible for 78 per cent of eutrophication, the harmful over-enrichment of water, which can kill fish and 32 per cent of soil damage.
Global production of eggs is a key driver of these impacts, having quadrupled over the past 50 years, according to researchers.
Dr Bartlett explained that caged birds are associated with a lower environmental impact because they consume less feed while producing the same quantity of eggs.
Feed production is a major contributor to the environmental footprint of egg production, using less feed reduces the inputs required to produce eggs and therefore lowers associated emissions.
“Organic free-range systems generally have higher environmental impacts because they tend to have lower productivity, higher feed requirements per egg produced, and lower crop yields for organic feed production. Together, these factors increase the land, feed and other resources required to produce the same quantity of eggs,” Dr Bartlett said.
“Reducing these impacts will require continued improvements in genetics, nutrition, feed production and farm management. The long-term goal should be to develop cage-free systems that combine high standards of animal welfare with improved production efficiency and lower environmental impacts,” she added.