Abstract
Our question “How many chickens does it take to make an egg?” was inspired by the successful replacement of egg-based mayonnaise with plant-based mayonnaise in general dining at the University of California, Santa Barbara, in order to increase animal welfare. Our indicator of improved animal welfare due to decreased egg consumption was the reduction in number of chickens in the stressful and unhealthy conditions of the US egg industry. To measure this we calculated the ratio of chickens to eggs and found it takes 6.3 chickens to make 1000 eggs (0.0063 chickens per egg). This equals 158 eggs per chicken, less than half the amount of eggs per laying hen because of mortality from hatching to entering the laying flock, including the disposal of male chicks. In addition, greenhouse gas emissions, irrigation water, reactive nitrogen, and land use would be reduced 43–98% from that of eggs. While the impact of plant-based mayonnaise was relatively small, we also estimated the substitution of eggs with tofu, which had a much greater impact: substituting 50% of eggs with tofu in first-year student breakfasts on all UC campuses would reduce the number of chickens in the egg industry by 9245. If this substitution was made by the US population, the welfare and environmental benefits would be 29 thousand times greater. Reducing egg consumption would greatly improve chicken welfare even if welfare certified eggs are replaced, since the requirements of the most commonly used chicken welfare certification programs do relatively little to reduce chicken suffering.
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Abbreviations
- CO2e:
-
Equivalent carbon dioxide emission; the amount of carbon dioxide emission that would cause the same amount of heating over a given time as the emissions of a mixture of other greenhouse gases
- GFI:
-
Global Food Initiative, University of California
- GHGEs:
-
Greenhouse gas emissions
- MT:
-
Metric ton
- NGO:
-
Non governmental organization
- SPI:
-
Soy protein isolate
- UC:
-
University of California
- UCSB:
-
University of California, Santa Barbara
- USDA:
-
United States Department of Agriculture
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Acknowledgements
We thank the University of California’s Global Food Initiative for the fellowship that funded AH during the 2016-2017 and 2017-2018 academic years. We thank Steven E. Smith (School of Natural Resources and the Environment, University of Arizona) for statistical analyses; Daniela Soleri (Geography, UCSB, for discussions and comments on drafts; Danielle Kemp (Residential Dining, UCSB) for data on mayonnaise use; John Lazarus (UCen Dining, UCSB), Katie Maynard (Sustainability, UCSB), Andrew deCoriolis (Farm Forward), and José Elias (Humane League) for discussions and suggestions for research; and four anonymous reviewers for Agriculture and Human Values.
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Cleveland, D.A., Gee, Q., Horn, A. et al. How many chickens does it take to make an egg? Animal welfare and environmental benefits of replacing eggs with plant foods at the University of California, and beyond. Agric Hum Values 38, 157–174 (2021). https://doi.org/10.1007/s10460-020-10148-z
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DOI: https://doi.org/10.1007/s10460-020-10148-z