Exploring The Carbon Footprint Of Laying Hens

It is widely recognised that the global population will continue to grow, driving an estimated 20% increase in demand of terrestrial animal protein between 2023 and 2050. In 2015, the global livestock sector was responsible for emitting 6.2 billion tons of CO. equivalent – accounting for 12% of all human-induced greenhouse gas emissions and 40% of the total emissions from the global agrifood system. Within this, global egg production contributed approximately 3.3% or 0.2 billion tons of CO. equivalent.

Reducing the carbon footprint of egg production is essential for mitigating climate change, ensuring environmental sustainability and supporting responsible future growth.

For decades, breeding programs have prioritised selecting laying hens with improved feed efficiency. Genetic advances in egg production, liveability, and feed utilisation – particularly through the use of alternative feedstuffs - have contributed to a significant reduction in carbon emissions per egg produced. By continuously selecting for traits such as feed conversion efficiency and the number of first-quality eggs per hen housed, the overall sustainability of the global egg industry continues to improve.

Beyond genetics, several additional factors influence the carbon footprint of egg production. Let’s explore some of them.

The choice between brown, black or white laying hens is often driven by consumer preference and marketing rather than production efficiency or environmental impact. However, because the genetic lines behind white and brown egg layer have been separated for centuries, there are notable differences between the various laying hen breeds.

In terms of carbon footprint per kilogram of eggs produced, white laying hens outperform brown laying hens. The difference is approximately 5.33%, with brown laying hens emitting 2.06 kg CO2 per kg of eggs up to 90 weeks of age, compared to 1.95 kg CO2 per kg of eggs for white laying hens up to 90 weeks of age. At 100 weeks the difference becomes even bigger, 6.31%.

The length of the egg production cycle also impacts sustainability. Shorter egg laying production cycles result in higher overall hen-day performance while the birds are in production, but as flocks age, egg production and feed conversion efficiency decline. Conversely, extending the production cycle reduces the need for flock replacements, which decreases emissions from the pullet-rearing phase.

For example, the carbon footprint of rearing brown pullets to 17 weeks of 7.88 kg CO2 per pullet, compared to 7.27 kg CO2 per white pullet, which is a difference of 7.74%!

In-ovo sexing technologies and fattening brother males offer potential solutions to ethical concerns associated with the culling of male layer chicks. Current in-ovo sexing techniques, applied between the 7th and 13th day of incubation, can identify and remove male embryos before hatching, significantly reducing the number of unwanted male chicks. However, these methods often require additional resources, such as laboratory material, labour and energy.

Alternatively, male chicks can be raised for meat production instead of being culled at day-old. While this approach addresses ethical concerns, it also increases resource consumption, including feed and housing, which negatively impacts the overall sustainability of egg production. Today, common practice involves culling day-old male chicks and using them in animal feed, biogas, or other industrial applications. The true sustainability impact of these alternatives remains an open question, as further research is needed.

Housing systems significantly influence the carbon footprint of egg production. Conventional and enriched cage systems have lower environmental impacts due to higher feed efficiency and reduced land use. Barn and aviary systems require more resources, as they generally lead to higher feed intake and slightly increased mortality rates.

Free-range and organic housing systems typically have the highest carbon footprints due to increased land and feed requirements. However, these systems may qualify for carbon credits, which could help to offset their overall environmental impact/lower their carbon footprint.

As the global egg industry moves towards greater sustainability, optimizing genetics, extending laying cycles, and making informed decisions about housing and male chick management will be key to reducing emissions while maintaining efficient and responsible egg production.

For this article, carbon footprint calculations were sourced from Eggbase Ltd, using data from Bovans Brown and Dekalb White laying hens.