That's not really the question though, the point is that it is very inefficient converting vegetable protein into animal protein, you could feed more humans on the vegetable protein than you could by feeding it to livestock and feeding the livestock to humans. So it's very strange for dutchguy to suggest that we couldn't convert to a plant-based diet sustainably.
I was talking about land where it is not possible to grow vegetable protein, which is quite a lot of farmland in this country.
Places where it is only possible to grow decent grass, and at a pinch cereal crops.
Both situations where animals can be grazed, finished or topped off with a small amount of grain and then be a source of good quality concentrated protein via meat and milk.
That comprises quite a few latitudes, climactic, and soil conditions,
Many upland and northerly latitudes in the UK for example.
And in many places overseas too, where for other reasons arable monocropping is inadvisable.
We can't grow soya beans at scale in this country for instance.
We can grow field beans and peas as a source of human protein (complete at least when combined with grains)
These do particularly well when rotated with grazing breaks.
'Continuous arable' - that is growing only plant crops with no grazing ley breaks is very bad for soils it depletes, them and is inherently unsustainable.
Healthy soil life is adapted to grazing herbivores, herbivores drive the nutrient cycle, via dunging, and even via their saliva, when grazing.
We are losing topsoil at an alarming rate by over mechanised farming, and by killing soil life with chemical inputs.
Combining livestock back into mixed farming systems where they can be part of the nutrient recycling, and waste management systems can boost overall productivity, and build soil, whilst reducing inputs, and regenerating ecosystems and biodiversity.
It's being done already on quite a few farms .
We also can't grow nuts in large enough quantities - at least not until we sort out the squirrel, rabbit and deer populations - there's a good argument for eating more of those critters.
We could definitely grow a lot more vegetables and fruit in this country.
But there's a different set of issues stopping us doing that - with which I've bored everyone rigid already.
Dutchguy has some 'strange' ideas about many things (imo) but in terms of him understanding farming and food production systems, and the problems / solutions therein I believe he's a bit more clued up than most on here.