I'm not a vegan or veggie, but can appreciate the philosophy behind those who adhere to the proper diet without mocking it. I watched on CNN how the Chinese raise cats and dogs by the boat load in deplorable conditions and then kill and skin them for their hides. (Who knows maybe they eat them too)
Now we all think that's wrong because we have dogs and cats as pets, but that's how the vegans and veggies feel when it comes to the inhumane mechanized farming and slaughtering cows, chickens, lambs, etc...
Same goes with animal testing on cosmetics and other non-medical products. I've seen smuggled video of testing on animals and chimps. I'm thick skinned but felt sick at what I saw. The horrific suffering and down right torturing of these poor creatures. If you guys saw it, you'd be disturbed. A simple Google search brings up loads of it.
There a bunches other sources of protein and iron out there besides meat. As long as you're knowledgeable, you can live a vegan lifestyle. I know 2 girls over the years who live it and are extremely healthy. It's a total lifestyle committment.
Rabbi, I'm no PETA fan, but your daughter can check out their wesbite as there are loads of links for vegan lifestyle and recipes, etc... This way she can be informed on the subject.
I'm a meat eater (just made chicken/vegetable stir fry and rice), but understand why people have philosophical, moral or religious objections to meat eating or animal testing.