I had a roommate in grad school who was a vegetarian also. She kept a big bottle of pond scum in the fridge that she drank, I think it was called spirillum or something like that. She was always eating weird stuff to give her the nutrients and stuff she wasn't getting from meat.
She also avoided the sun at all costs. So the stuff turned her green.
Having been in art departments all throughout college, I knew lots of vegetarians and vegans, but they were all having issues because of their lack of a proper diet. I mean, sure, you can say that it is ok to eat all vegetarian or vegan, but everyone I ever knew who ate this way had to amend something that they weren't getting.
Sure, sure, religious reasons, or you love animals... sure sure... we can spin all day on whether letting cows and sheep go back out into the wild is humane or not. but, it seems kind of weird for a guy who says that letting a cat stay outside is inhumane to make that argument.
Horses are such a weird thing to see people keeping nowadays. Most people who keep them just do so as field decorations. They are like the MySpace of work animals. And, I guess that makes donkeys the Yahoo Messenger of animals.