I eat mostly large animals. The majority of my daily calories come from pasture-raised beef and I have often pondered whether this results in less overall mortality to animals than a vegan diet.
In the interests of fairness, I have used soy as my sample vegan food. I chose this because it is the highest in calories of common legumes and thus, I have tried to not skew the results by choosing a low-calorie vegan food.
I have also used the lowest possible estimate, derived from the scientific literature, of animals killed per acre by plant agriculture and have excluded secondary deaths resulting from predation, ancillary deaths from secondary poisoning, or deaths of insects from my primary workings.
How many animals are killed by plant agriculture?
This is a difficult question to answer. There are many nuances, including primary deaths (from threshing and harvesting) through to pest-control, and secondary deaths resulting from predation due to loss of plant cover (a significant factor in loss-of-life from agriculture).
Many estimates have been made and Fischer and Lamey in a 2018 have summarised these. (1) Included in this review are previous estimates of 15 field animals killed per acre by Davis in 2003, whereas Archer in 2011 estimated a much higher all-cause mortality rate resulting from plant agriculture of around 40 animals per acre. Fischer and Lamey do an excellent job of examining the available research and disputing the oft-quoted 7.3 billion lives taken per year by plant-based agriculture and I highly recommend you read it.
If we use the very lowest estimate of deaths per acre, excluding deaths from agriculture related predation, we get a figure of approximately 2.5 deaths of animals per acre from plant agriculture.
I have used for these calculations, an average man’s baseline caloric requirements of 2200 kcal per day.
Estimation of soy required:
Yields in New Zealand are estimated at 20 bushels per acre, (2) and there is around 27.3 kg of soy beans per bushel. (3) This would provide for 545 kg of soy beans per acre. There are 4.46 calories per gram of soya, and therefore, to provide the 803,000 kcal required per year, 180 kg of soya would need to be consumed.
Thus, 1/3 of an acre would support someone’s reasonable, minimum requirements for energy over a year, resulting in the loss of a minimum of 1 life, or as many as 5-13 animals with higher estimates drawn from the research above.
Estimation of beef required:
The average yield of meat from a fully-grown beef steer is approximately 62.5% of a weight of 550 kg. This results in around 344 kg of meat. Each gram of beef supplies 3.32 kcal, and so, to supply the same amount of energy as above, we would require 242 kg of beef (or less than ¾ of a beast). So, the cost to life of the beef is approximately 1 life. There may be some ancillary deaths resulting from beef raising but these are likely to pale in comparison to those of plant-based agriculture.
Pasture-raised beef provides little ancillary damage to life compared to raising protein-crops, especially in a pastured agri-system like that in New Zealand. Beef supplies nutrient-dense, and calorie dense food. Soy conversely results in at least as much loss of life, likely to be much higher, and is less nutrient-rich, especially with respect to the essential and non-essential nutrients required by the omnivorous human animal. So, soy and more importantly less ‘calorie-dense’ vegetarian foods would therefore offer a worse life-calorie ratio and would result in significantly greater numbers of lives lost when compared to large ruminants. It is highly likely that vegan protein foods result in more loss of life than beef.
This in no way means that we should eschew all vegetables or legumes. In fact, the opposite. I believe it provides a rationale for healthy, ethical omnivourism, with a focus on:
- Reducing food waste
- Appropriate land use (i.e. not ‘forcing’ land inappropriate for either cropping or pasturing to be used as such)
- Proper consideration of the impacts of all types of food production
1. Fischer B, Lamey A. Field Deaths in Plant Agriculture. Journal of Agricultural and Environmental Ethics. 2018;31(4):409-28.
2. Blair ID, Tan CF, Palmer TP. Soya bean trials in Canterbury. New Zealand Journal of Agricultural Research. 1966;9(4):894-908.
3. Rules. JCoA. SECTION 600.TABLE B STANDARD WEIGHT PER BUSHEL FOR AGRICULTURAL COMMODITIES: US Government; [Available from: ftp://www.ilga.gov/jcar/admincode/008/00800600ZZ9998bR.html.