It's actually not a stupid idea, given that broadly speaking it takes several kilos of grain to produce one kilo of meat. This ought to be done somewhat gradually, though, since most people probably don't want to eat copious amounts of feed corn or soybeans.
And the idiot speaketh. Livestock is the cheapest way to turn low value feed grain and forage into protein. There is lots of land that is fit for nothing else but foraging livestock, and much more ground that cannot support high intensity vegetable production needed to offset the lack of protein from reducing or eliminating livestock, and that is before you wade into a discussion of the merits of organic versus conventional farming, and all you need to know about that is to look into what has befallen Sri Lanka mandating their farmers go organic.