It is often reported that 6-20kg of cereals are required to produce 1kg of beef. These figures certainly do not apply in the case of Europe and the calculation is incorrect even at a global level!

Taking the EU ruminant production system as an example, this is based on grazing and mixed systems. Grasslands provide a significant role in fodder used to feed the livestock, converting grass into highly nutritious food. Also, concentrated feed given to livestock are composed of crop residues and by-products of cereals (from milling starch factory, distillery), protein crops (pea co-products), oilseed (oilcake rapeseed, sunflower), fruit (pulp citrus), vegetables and tubers (pulp beet, potato) as well as milk (whey from cheese factories). 

Therefore, the ration of human-edible food in the ruminant sector grazing and mixed systems is very low. At global level, human-edible feed materials represents about 13% of the global livestock feed ration.

Source : GLEAM, FAO

A recent study carried out by some researchers of the Friedman School of Nutrition Science and Policy[ref]available on  <https://www.elementascience.org/articles/10.12952/journal.elementa.000116/> Elementa magazine – Science of the Anthropocene, [/ref], has showed how comparing ten different diets, the more vegan oriented shows a worse and less differentiated use of the “resource soil”. 

Ten very different diets representing ten ways to influence the environment, ten ways – perhaps – to influence our and natural life, so also world biodiversity and somehow the cultural heritage such as the landscape. Among the ten diets, those excluding animal origin food, generally believed more “virtuous”, have revealed to be less efficient in land managing as focusing only on arable and comfortable land exploiting.

According to the results, land use connected to vegan diet would be able to feed fewer people than a land use based on omnivores diet. So, it means that completely and suddenly eliminating animal-based products may not be the most sustainable option in the long term for mankind. 

A vegan diet may not be the best choice in function of the human population, protein needs and world soil resources management. Indeed in a paradox scenario made of 100% vegans, we would need more arable lands, as ingredients of the vegan diet are produced with a very low efficiency i.e. in grazing lands.

Not all agricultural lands are comparable in terms of theoretic productivity: some of them, for example, give their best with cereals, but they are inefficient for fruit and vegetable productions (i.e. clayey soils poor in water resources ), other lands, on the other side, fit only for pastures as vegetable cultures would represent a too high energetic factor choice (stones density, soil depth, slope incidence, etc).