Impact of corporate commitments to source cage-free eggs on layer hen housing: Preregistration for an observational study


Over the last decade, hundreds of companies around the world have committed to source cage-free eggs by 2025 or earlier. Commitments sometimes result from conversation with groups advocating to improve the treatment of animals, as cage-free housing is widely believed to provide better welfare for egg-laying hens. When conversation does not work, advocacy groups may run a campaign of public pressure, including protests or shaming in the media, which usually leads to a commitment. In this preregistration, we describe a detailed plan to use data from many countries on the share of hens living cage-free to understand the effect of cage-free commitments. We expect that commitments will shift the industry from caged to cage-free housing for hens. To test this, we will look at data from before and after commitments were made and in countries with and without commitments. We will also consider other factors, like changes in the law and illnesses that kill hens, that could affect how they are housed. We suspect that commitments and housing affect each other, so we will use advocacy groups’ campaigns as a statistical tool to further clarify the cause-and-effect relationship. When we complete the planned study, it will provide thorough evidence on the impact of cage-free commitments, which might be useful to advocacy groups, companies making commitments, and the egg industry.