most of the crops fed to animals are parts of plants people can’t or won’t eat.
Not relevant. The field that is used to grow food stock for animals could have been used to grow food stock for humans. Potatoes have a high calorie count and are not particularly difficult to grow.
You’ll get far more calories out of the field of potatoes than a field of cows, unless you’re packing them in at the same density as the potato plants which I’m assuming you’re not.
You’ll get far more calories out of the field of potatoes than a field of cows,
if the land is unsuitable for crop production, you can often still raise cattle on it.
You still need to grow food to feed the cattle, if only for winter stock, so you have to find a fertile field to grow food stock, so that field could be used for growing crops and the field that’s unsuitable for anything else could just be, well not used. There’s absolutely no scenario where cattle are going to be more sustainable than crops.
