The problems that frequently lead to the argument for cutting meat consumption for ecological reasons are all actually concerns with industrialized meat production practices, not with meat production itself. We don't need to cut meat production, we need to change how we raise, process, and distribute the meat. Raise thousands of cows in concrete pens in a remote area will always require too many inputs and produce too many unwanted outputs because it's not part of a larger ecosystem.
Ruminants like cows and sheep play a vital role in managing pasture and creating fertilizer. Chickens play a vital role in pest management and creating compost. Chickens and hogs both play a role in making productive use of waste products, eating food scraps and garden waste that would otherwise be lost.
Heck, we couldn't even have egg and milk production at all without producing meat or culling animals along the way. Only 50% of eggs hatched are female, we have to do something with the males. And dairy cows will only produce milk for 6-12 months after giving birth, meaning there are calves that need to play a part in the system as well.
That doesn't even get to the challenges of trying to raise crops without animal byproducts. Where does all the fertilizer come from?