It is popular “common knowledge” that a diet with less or no animal products is healthier for both the people and the planet. However, academic studies continue to question this conclusion.
A recent investigation by a pair of researchers from Virginia Tech and USDA Agricultural Research Service asked what would happen if animals were removed from U.S. agriculture. The result of the data analysis countered the “common knowledge.” While removing livestock would slightly lower greenhouse gases from agriculture, the nutritional output of U.S. ag would fall below the population’s needs.
“The 2015 Dietary Guidelines Advisory Committee claimed that plant-based diets would promote health and improve long-term sustainability of the U.S. food supply,” read the introduction of the paper documenting the investigation. It was published in the Nov. 13, 2017 issue of the Proceedings of the National Academy of Sciences by authors Robin White and Mary Beth Hall.
“Implicit in such reports is the idea that modification or elimination of animal agriculture would offer benefits to society with minimal and acceptable deleterious effects,” they continued. However, the findings of their data analysis suggest otherwise.
Currently, all of U.S. agriculture is credited with 9 percent of the country’s total greenhouse gas (GHG) emissions. Half of that—or about 4.5 percent of the country’s estimated total—is generally credited to U.S. livestock.
The widely-repeated claim that livestock account for 18 percent of total GHG emissions comes from the mostly discredited “Livestock’s Long Shadow” report from 2006 by the United Nations. Even before the report was criticized for effectively comparing apples to oranges in its method, the 18 percent figure supposedly applied to the global community overall, not specifically the U.S. Despite this, the 18 percent figure is often quoted in even U.S. media by those unfamiliar with the report’s history or scope, or the fact the U.S. livestock industries are among the most efficient in the world.
White and Hall’s data analysis suggested that the removal of livestock would reduce total U.S. GHG emissions by 2.6 percentage points. The reason the total removal of livestock would not remove the GHG emissions currently attributed to them would be the GHG emissions associated with the production of synthetic fertilizer in place of manure and the disposal of feed byproducts currently eaten by livestock.
Regarding human nutrition, the researchers noted that, “Animal-derived foods currently provide 24 percent of the energy, 28 percent of the protein, 23-100 percent of the essential fatty acids, and 34-67 percent of the essential amino acids available for human consumption in the United States.”
This included half of food-sourced calcium and essential vitamins A, B12, and D, as well as several essential amino and fatty acids necessary for healthy brain development in infants.
“Although modeled plants-only agriculture produced 23 percent more food, it met fewer of the U.S. population’s requirements for essential nutrients,” the report read. “When nutritional adequacy was evaluated by using least-cost diets produced from foods available, more nutrient deficiencies, a greater excess of energy, and a need to consume a greater amount of food solids were encountered in plants-only diets.”
The researchers concluded their report, calling the diet that would result from the removal of livestock from U.S. agriculture “nonviable in the long or short term.”
Other issues
Though the investigation focused on the two points of GHG emissions and nutrient availability, the researchers pointed out that the impact of livestock on the U.S. culture and economy is wide-ranging. They estimated that U.S. livestock industries directly employ over 1.6 million people and accounted for $31.8 billion in export value, for instance. The export value attributable to livestock-sourced exports accounted for 22 percent of the income for all agricultural exports.
“From a global standpoint, export of nutrient-dense livestock products from developed countries has been identified as a critical priority for promoting global food security in the face of a changing climate,” the researchers wrote.
They also noted that livestock give more than food.
“A multitude of animal-derived products are used in adhesives, ceramics, cosmetics, fertilizer, germicides, glues, candies, refining sugar, textiles, upholstery, photographic films, ointments, paper, heart valves, and other products.”
Specifically, regarding fertilizer, the researchers estimated that livestock give approximately 4.5 million tons of nitrogen fertilizer in the form of manure.
Another noteworthy contribution of livestock to the overall U.S. condition is as recyclers. An estimated 47.6 million tons of “human-inedible food and fiber processing byproducts” are consumed by livestock. If not consumed by livestock, these byproducts would need to be disposed of in other ways.
Outside the realm of human nutritional needs, the researchers pointed out that the most common pets in the U.S.—cats and dogs—are carnivores needing animal protein. If livestock were to be removed from U.S. agriculture, the nutritional needs of millions of pets would additionally need to be met by plant-based protein.
White and Hall acknowledged that their research was limited by incomplete data, which necessitated several assumptions. The most unrealistic of these were:
- Grain previously consumed by animals will be available for human consumption;
- Tillable land previously used for livestock feed will be used for human food production;
- Most increases in plant-foods will be in grains and legumes rather than fruits or vegetables; and
- Humans can and will consume soy flour with no negative health impacts.
“Future work should focus on a more systems-oriented approach to use socioeconomic modeling to evaluate likely land-use changes associated with livestock removal,” they recommended. — WLJ
