Canada's dairy supply management system provides milk year-round but unnecessarily disposes of overproduction. A lack of transparent data on discarded milk means that the scale of this issue is unknown. This hinders actions to mitigate the potentially large environmental, economic and nutritional costs of avoidable, on-farm milk waste. Here we estimate the volume of surplus milk discarded on farms using a material flow analysis approach, and assess the related environmental and nutritional costs. By our estimates, over 6.8 billion liters of raw milk vanished from Canadian dairy farms since 2012 (totaling a value of $14.9 billion CAD). We calculate this is equivalent to 8.4 million tonnes of CO2 emissions and enough milk for 4.2 million people (11 % of the Canadian population) annually. We suggest increasing transparency on the volume overproduction, reducing incentives for farmers to overproduce, and updating quotas to reflect shifting dietary needs as actions to align the Canadian dairy sector with broader food-system sustainability objectives.

中文翻译：

---

自 2012 年以来，加拿大牛奶浪费了超过 60 亿升


加拿大的乳制品供应管理系统全年提供牛奶，但不必要地处理过剩的牛奶。缺乏关于废弃牛奶的透明数据意味着这个问题的规模是未知的。这阻碍了减轻可避免的农场牛奶浪费可能带来的巨大环境、经济和营养成本的行动。在这里，我们使用物料流分析方法估算农场丢弃的剩余牛奶量，并评估相关的环境和营养成本。据我们估计，自 2012 年以来，超过 68 亿升生牛奶从加拿大奶牛场消失（总价值 149 亿加元）。我们计算出这相当于每年 840 万吨二氧化碳排放量和 420 万人（占加拿大人口的 11%）的足够牛奶。我们建议提高产量过剩的透明度，减少对农民过度生产的激励，并更新配额以反映不断变化的饮食需求，以使加拿制品行业与更广泛的食品系统可持续发展目标保持一致。