Nutritional and Greenhouse Gas Implications of Removing Animals from U.S. Agriculture

Available at: https://doi.org/10.1073/pnas.1707322114

Commentary

Agricultural greenhouse gas (GHG) emissions are one of the main environmental problems, and it has been suggested that reducing the consumption of livestock and animal-derived foods will reduce GHGs.

Therefore, eliminating animals altogether provides extreme bounds to potential mitigation options and requires minimal assumptions to model, resulting in a study that quantified the annual nutritional, and GHG impacts of eliminating animals from U.S. agriculture.

First, foods of animal origin account for 24% of the total energy available for human consumption in the United States. Protein makes up 48%, essential fatty acids 23-100%, and essential amino acids 34-67%. And the U.S. livestock industry accounts for $31.8 billion in exports, while 1.6 x 10 employs 6 people. Livestock recycling is more than 43.2 x 10 9 kg of human inedible food and fiber converted into human edible food, pet food, industrial products, and processing byproducts, and 4 x 10 9 kg of fertilizer.

The modeled plant-only agriculture was supposed to produce 23% more food than today, but less than the U.S. population requirement for essential nutrients. Using available foods and least-cost diets from these models and assessing nutritional adequacy, it was found that a plant-only diet would encounter many nutrient deficiencies, much excess energy, and the need to consume more solid foods.

However, although the simulation system reduced the estimated agricultural GHG (28%), it did not completely offset the animal contribution to GHG (49% in this model). This research assessment suggests that eliminating animals from U.S. agriculture would not only reduce GHG emissions, but would also leave the U.S. population unable to support its nutritional requirements.