Isaac Emery

PNAS 2018 February, 115 (8) E1703.

In “Nutritional and greenhouse gas impacts of removing animals from US agriculture,” White and Hall (1) imagine a future without animal agriculture but fail to address perhaps the single most influential aspect of livestock on US agriculture: land use for feed crops. The authors unrealistically assume that without livestock, Americans would continue to grow animal feed and incorporate it into human diets. Feed crops are unpalatable for humans without processing, increasing our consumption of processed foods containing corn and soybean oils and high-fructose corn syrup in White and Hall’s scenario (figure 3 in ref. 1). Feed crops take up roughly 75% of US cropland, and when fed to livestock represent an inefficient source of edible calories (2). Without livestock, those 240 million acres could be used to grow vegetables, biofuel crops, food for export, and provide critical habitat for native wildlife. White and Hall’s (1) assumption that biophysical, rather than economic, factors limit the production of specialty crops in the US Midwest is not supported by historical data or current practices by small vegetable producers nationwide (3, 4). Additionally, high fertilizer loads and other farming practices used to maximize grain yields are the primary drivers of biodiversity loss in American streams and recurring dead zones in the Gulf of Mexico and elsewhere (5, 6). By eliminating the need for animal feed, farmers could transition to a wider variety of grasses, grains, pulses, vegetables, and fruits that would be healthier for humans and the environment.

See http://www.pnas.org/content/115/8/E1703