Medieval animal use patterns are way greener than what we have now. Pigs acted as garbage disposals, then by day a professional swineherd would take everyone's pigs out to the forest. Cows and sheep ate grass off useless rocky land, and were walked to where they'd be slaughtered.

But I don't really think this is a deep argument for how things should be today. How can you restructure cities so pigs can commute between homes and the forest? How can cows walk all the way to pasture and back to the city for slaughter? I don't think it's actually possible; the density of modern cities breaks these models. But that same density is ecologically required a thousand other ways.