A heavy-hitting scientific journal, Proceedings of the National Academy of Science of the United States of America, published a paper late last year which examined the scenario of the total removal of animals from US agriculture.

The publication ranks in the top 200 of almost 30,000 listed academic journals globally. The study was conducted by researchers from Virginia Tech and the USDA.

The goal of the study was to determine the impacts of removing farmed animals on food supply adequacy and greenhouse gas emissions (GHG).

Greenhouse gas

Animal agriculture accounts for around 49% of the USA’s agricultural emissions at present. Because of the needs to synthesise fertiliser to replace animal manures, dispose of human-inedible by-product feeds that had been used to feed animals and produce additional crops on land previously used by animals, total GHGs from US agriculture reduced by 28% when animals were eliminated, as opposed to the full 49%. In terms of total US emissions, a plant-based production system would reduce emissions by 2.6%.

In terms of total US emissions, a plant-based production system would reduce emissions by 2.6%

However, when the authors looked at the breakdown of consumer’s diets in a plant-only agricultural system, problems arose.

Firstly, they state: “It is entirely possible to meet the nutrient requirements of individual humans with carefully crafted, unsupplemented plant-based rations, but this can be a challenge to achieve in practice for an entire population.”

Essential micronutrients

Relative to an animal-based diet, plant-based diets were shown to provide sufficient macronutrients but lacked some essential micronutrients - namely calcium, vitamin A, vitamin B12 and fatty acids EPA, DHA (vital for well-functioning neural and cardiovascular systems and intellectual development) and arachidonic acid (proper hormone function).

Another limitation to the plant-based dietary scenario was the total amount of food that an individual needed to consume to derive enough nutrients.

The simulated plant-based diets required a person to consume between 444g and 522g more food solids (less water fraction) than diets including animal products. The lower solids intake is evidence of the higher essential nutrient density of animal-based foods.

In a scenario where only products produced on USA soil were used to make up these diets, the animal-based diet proved to be 15% cheaper. Where imports were permitted, it was 37% more expensive than the plant-based diet.

Other difficulties

Further points also mentioned included:

  • The fact that animal products are currently used in adhesives, ceramics, cosmetics, fertiliser, germicides, glues, candies, refining sugar, textiles, upholstery, photographic films, ointments, paper, heart valves, hormones for medical use, vaccines, blood coagulation agents and wound cleaning agents.
  • Animal agriculture directly employs more than 1.6m people in the USA and generates $32bn annually – the equivalent to 22% of all US agri-exports.
  • A serious concern about whether inevitable increase in soy product consumption would lead to increased rates of hormone-related health disorders. At present there is a gap in the literature such that a maximum recommended daily intake of soy products has not been determined.
  • What to do with the 1.68m hectares of untillable land in the USA, currently only suitable for ruminant-based food production?
  • The authors conclude broadly that the removal of animals from US agriculture would reduce the sector's GHG emissions, but would also create a food supply incapable of supporting the US population’s nutritional requirements without supplementation.

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