You concede this point but surely the omnivorous diet uses the least amount of arable land since we can augment our caloric intake with meat.
Arable land is defined: capable of being ploughed and used to grow crops. I imagine land allocated for poultry could be easily put to the plow, less so for pork though, and hardly at all for beef, dairy, mutton, or goat. This after all is probably why man first started to keep herds in the first place, to make use of poor soil to produce food for a growing population and as a hedge against famine resulting from drought or blight.
Essentially I’m willing to let someone else share some of my 1.024 acres of arable farmland in exchange for meat raised from non-arable land. If our concern is in feeding the most people then reducing our dietary options is clearly not the best idea.
And then there’s fish! Although I’m sure vegans might prefer us to eat kelp, it’s not because farming kelp is more “sustainable.”
Vegans have only two appeals: eating vegetarian is healthier or killing animals is morally objectionable. There is plenty of evidence to suggest that attempting to consume only vegetables is fraught with as many nutritional pitfalls as attempting to eat only meat. Many advocates of vegetarian diets focus on replacing animal protein, but animal fat is just as important to a healthy diet. Any attempt at resolving all of these dietary needs while simultaneously eliminating the animal kingdom as a food source is foolhardy.
Which leaves the moral question. Vegans argue that taking the life of a young animal, especially one bred for that purpose, to feed your family is evil. So I ask this… if a group of Vegans we’re trapped on a lifeboat and ran out of food and water, would it be preferable to eat a fish or a fellow vegan? Ultimately that’s what they’re arguing. If it’s “wrong” to eat meat, billions of people will have to leave the lifeboat. It may seem noble to take chances with one’s own nutrition in order to save an animal from suffering, and if you live in a post-modern country where there is a vast supply and variety of foodstuffs, you’re not really risking much. But to proclaim moral superiority of a lifestyle that cannot be applied globally without people dying makes no sense.
Surely any sane person would agree, killing an animal to keep one human alive for one more day is worth it. Killing billions of animals daily to ensure billions of people get enough to eat must also be morally right.