That is incorrect. Around 40% of fields are used to grow food for livestock, as well as a quarter of fish caught being fed to animals. I found this article saying we could slightly increase byproduct use for feed, but they are minor improvements. https://www.nature.com/articles/s43016-022-00589-6

[–] commie@lemmy.dbzer0.com 1 points 2 hours ago (1 children)

from the abstract

We then analysed the potential of replacing food-competing feedstuff—here cereals, whole fish, vegetable oils and pulses that account for 15% of total feed use—with food system by-products and residues.

a distinct minority of animal feed competes with human food

[–] Squirrelsdrivemenuts@lemmy.world 1 points 54 minutes ago (1 children)

Yes, humans cannot eat grass (for example), but grass is also not a byproduct. And fields used to grow grass could be used either for other (human-edible) crops, habitation or for wildlife restoration.

[–] commie@lemmy.dbzer0.com 1 points 49 minutes ago

fields used to grow grass could be used either for other (human-edible) crops

some. I doubt that's true for most grasslands.