h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Well, all the other meat animals would too. And, it may be WORSE for the environment in a way, there would be no vegetables left to create fuels like ethanol. Also, with all the beans we would be eating, would we add more methane?

No, cows would not overpopulate the planet. Cows didn't overpopulate the planet before humans evolved, so what possible logic dictates that they would now.

Obviously we would have to give up milk too. If we didn't we would have to still kill all the bulls but not eat them (not very environmentally friendly) or let them loose and then bulls would overpopulate the planet!

The British population is not monolithic! The point being that not everyone will stop consuming meat at the same time (in reality, I expect few people would even care so much as to reduce their consumption without government-intervention) and we wont be left with a surplus of live animals.

I hope that you are either quite young or not serious but you should realise that most animals destined for cellophane packaging in your local supermarket are deliberately reared for your consumption and that it is not necessary for us to prey upon them to keep their numbers under control.

As regards your point about using up all the vegetables; a) the land freed from grazing animals would be available for much more energy-efficient growth of more vegetables and b) the grain that is currently used for animal feed would be available for human use. It takes approximately five times as much grain (possible more?) to enable a human to consume meat than if the human were to sustain themselves on the grain directly (this is due to the various inefficiencies of the process including the energy wasted by the movements, heat and excretions of the animal).

Even though they are kept especially for human consumption, what exactly would happen if everyone became vegans? All the meat animals would, most likely, be let free. Of course, all the animals would now breed, and with only a few wild animals who only take what they need, they would overpopulate. You may just say that we should kill them all, but that would really just defeat the purpose. Also, though I may be serious, I didn't expect many serious responses to a conversation with the word "moo" in the title.