Summary
The authors calculated the land use and demographics of the chickens that would be required if the United States continued to consume 20 million metric tons of chicken meat annually, but switched to slower growing breeds with outdoor or pasture management.
The authors created estimates of current conventional flocks (Ross 308) and flocks of three slower growing chicken breeds. They derived estimates from data and guidelines published by the USDA National Agricultural Statistics Service (NASS), National Chicken Council, Global Animal Partnership (required outdoor access space for certification), Humane Farm Animal Care (required pasture space), Aviagen (data on slow-growing breeds).
If all conventional chickens were replaced with slower growing breeds, the chicken population is estimated to increase by 44.6%–86.8%, depending on the breed. Using CAFOs to raise the slower growing breeds would require 19.9%–30.6% more land. Occasional outdoor access only resulted in a minor increase in land compared to exclusive CAFO housing. However, 43.8%–60.1% more land would be required to house slower-growing breeds on pasture.
If the goal was to switch to slower growing breeds, but keep land use the same, it would require a significant reduction in meat consumption. For example, a 17.3% decrease to maintain intermediate growing breeds raised in CAFOs.
A strength of this study is the consideration of direct and indirect (land for feed) land use to raise chickens. A limitation acknowledged by the authors is that the estimates do not take into account factors such as the potential differences in mortality or slaughtered carcass rejection rates.
According to the authors, this study implies that significantly reducing chicken consumption could reduce the barriers to shifting to slower-growing breeds while mitigating the impact on wild habitats.
In 2018, over nine billion chickens were slaughtered in the United States. As the demand for chickens increases, so too have concerns regarding the welfare of the chickens in these systems and the damage such practices cause to the surrounding ecosystems. To address welfare concerns, there is large-scale interest in raising chickens on pasture and switching to slower-growing, higher-welfare breeds as soon as 2024. We created a box model of US chicken demographics to characterize aggregate broiler chicken welfare and land-use consequences at the country scale for US shifts to slower-growing chickens, housing with outdoor access, and pasture management. The US produces roughly 20 million metric tons of chicken meat annually. Maintaining this level of consumption entirely with a slower-growing breed would require a 44.6%–86.8% larger population of chickens and a 19.2%–27.2% higher annual slaughter rate, relative to the current demographics of primarily ‘Ross 308’ chickens that are slaughtered at a rate of 9.25 billion per year. Generating this quantity of slower-growing breeds in conventional concentrated animal feeding operations (CAFO) would require 90 582–98 687 km2, an increase of 19.9–30.6% over the 75 577 km2 of land used for current production of Ross 308. Housing slower-growing breeds on pasture, the more individually welfare-friendly option, would require 108 642–121 019 km2, a 43.8–60.1% increase over current land use. Allowing slower-growing breeds occasional outdoor access is an intermediate approach that would require 90 691–98 811 km2, an increase of 20–30.7% of the current land use, a very minor increase of land relative to managing slower-growing breeds in CAFOs. In sum, without a drastic reduction in consumption, switching to alternative breeds will lead to a substantial increase in the number of individuals killed each year, an untenable increase in land use, and a possible decrease in aggregate chicken welfare at the country-level scale. Pasture-based management requires substantial additional land use. These results demonstrate constraints and trade-offs in animal welfare, environmental conservation and food animal consumption, while highlighting opportunities for policies to mitigate impacts in an integrated manner using a One Health approach.