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.

中文翻译：

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做一个鸡蛋需要多少只鸡？加州大学及其他地方用植物性食物替代鸡蛋的动物福利和环境效益

我们的问题是“做一个鸡蛋需要多少只鸡？” 灵感来自加利福尼亚大学圣巴巴拉分校在普通餐厅中用植物性蛋黄酱成功替代鸡蛋蛋黄酱，以增加动物福利。由于鸡蛋消费量减少，我们的动物福利改善指标是在美国鸡蛋行业的压力和不健康条件下鸡数量的减少。为了衡量这一点，我们计算了鸡与鸡蛋的比例，发现需要 6.3 只鸡才能生产 1000 个鸡蛋（每个鸡蛋 0.0063 只鸡）。这相当于每只鸡 158 个鸡蛋，因为从孵化到进入产蛋群的死亡率，包括雄性小鸡的处置，不到每只蛋鸡的鸡蛋数量的一半。此外，温室气体排放、灌溉用水、活性氮、土地利用将比鸡蛋减少 43-98%。虽然植物性蛋黄酱的影响相对较小，但我们也估计了用豆腐代替鸡蛋的影响更大：在所有 UC 校园的一年级学生早餐中，用豆腐代替 50% 的鸡蛋将减少数量鸡蛋行业的鸡只减少了 9245 只。如果由美国人口进行这种替代，福利和环境效益将增加 29000 倍。即使更换了福利认证的鸡蛋，减少鸡蛋消费也会大大改善鸡的福利，因为最常用的鸡福利认证计划的要求对减少鸡的痛苦几乎没有作用。我们还估算了用豆腐代替鸡蛋的影响更大：在所有 UC 校园的一年级学生早餐中用豆腐代替 50% 的鸡蛋将减少 9245 只鸡蛋行业的鸡。如果这种替代由美国人口制造，福利和环境效益将高出 2.9 万倍。即使更换了福利认证的鸡蛋，减少鸡蛋消费也会大大改善鸡的福利，因为最常用的鸡福利认证计划的要求对减少鸡的痛苦几乎没有作用。我们还估算了用豆腐代替鸡蛋的影响更大：在所有 UC 校园的一年级学生早餐中用豆腐代替 50% 的鸡蛋将减少 9245 只鸡蛋行业的鸡。如果这种替代由美国人口制造，福利和环境效益将高出 2.9 万倍。即使更换了福利认证的鸡蛋，减少鸡蛋消费也会大大改善鸡的福利，因为最常用的鸡福利认证计划的要求对减少鸡的痛苦几乎没有作用。如果由美国人口进行这种替代，福利和环境效益将增加 2.9 万倍。即使更换了福利认证的鸡蛋，减少鸡蛋消费也会大大改善鸡的福利，因为最常用的鸡福利认证计划的要求对减少鸡的痛苦几乎没有作用。如果由美国人口进行这种替代，福利和环境效益将增加 2.9 万倍。即使更换了福利认证的鸡蛋，减少鸡蛋消费也会大大改善鸡的福利，因为最常用的鸡福利认证计划的要求对减少鸡的痛苦几乎没有作用。