In most cases, this is actually done to create feed crops like soy and corn. Most of the agricultural fields in the world are used to feed animals either used for slaughter or for dairy and not to feed people directly.
Feeding the same amount of people directly instead of feeding animals and then eating them could be done with a fraction of the agricultural resources.
Dairy production is actually one of the most environmentally impactful things that we do, if we want to go that route.
Soy and corn, particularly corn, have many uses beyond animal feed.
> Most of the agricultural fields in the world are used to feed animals either used for slaughter or for dairy and not to feed people directly.
Please support that statement.
> Livestock is the world's largest user of land resources, with pasture and arable land dedicated to the production of feed representing almost 80% of the total agricultural land. One-third of global arable land is used to grow feed, while 26% of the Earth's ice-free terrestrial surface is used for grazing.
So a lot of that land could be used for reforesting. And if it would be so simple to use that land to raise cattle, why are there factory farms then?
It sounds cheaper to raise the cows on grass which is free food, unlike rations. Clearly the amount of meat produced that way is not sufficient for the demand.
There are all sorts of alternatives to that paradigm, but none allow us to compare a single metric for both. The nature of the debate reminds me of the apocryphal drunk, looking for his car keys below the streetlamp even though he knows he didn't lose them there.
If we keep attacking the problem from the wrong angle, we won't ever have a good solution.