>Any form of meat isn't going to be environmentally friendly compared to a
So you'd plow under native grasslands to plant a vegetable garden?
There is a big disconnect -- yes, many modern methods of factory farming meat are not environmentally sound. Confined animal feeding operations dependent on grains have a plethora of ethical, environmental, and health issues.
But because vegetarians/vegans may have an advantage in that narrow view does not follow that they are superior in all ways to proper meat production.
The simplest example is a goat.
Why, in an arid region like the Mediterreanean, should you limit your diet to vegetables when there are large areas of where goats can go up in the hills where you can't grow your own food, and convert plants inedible to humans into valuable human food?
Even cows are perfectly understandable. It doesn't take many man-hours to maintain pasture. For relatively few man hours, the cows can go out, eat, convert something inedible to man (grass), and produce large amounts of valuable food in milk, meat, and if you're a Massai tribesman even blood.
Pigs provide a great way to take spoiled foods -- breads don't do much for a compost pile, nor cheese or eggs for that matter, or the odd dead chicken found in the yard -- and produce useful meat for people (as well as good manure for gardens, properly composted of course.) Like cattle, certain cuts of pork are also easy to cure for long term storage of a year or so at room temperatures...providing high density protein and fat year round even if weather has caused crops to fail.
Vegetarianism / Veganism is not environmentally responsible, truly adopted it requires limiting our food choices and expanding the land we intensively raise human foods on while abandoning to human consumption much land where food animals can co-exist quite nicely with a diverse ecosystem. A mixed diet including responsibly raised meat on pasture and open rangeland would have a smaller footprint on this planet.