Going to need a source for that because all the information i've seen shows that there is absolutely not enough land to be able to sustain the current levels of meat consumption.
You're sort of mixing up things here. Yes, there is enough land in some parts of the world (Canada, US), but that's not the point.
I specifically said not full grass feed. That's what people believe and assert there is not enough land for. You can still have some grass feeding, conjoined with grain feed. The animals get to be outside, have space to move around, but 1000 acres instead of 100k acres needed for full grass feeding the same herd.
As factory farms already feed those herds, clearly there's enough grain to feed them.