What's a good alternative for Boar/ Hog Hair Paint Brushes?

I'm trying to get into oil painting and right now I just have a set of nylon paint brushes. They're fine I guess but I think most oil painters use hog hair brushes, right? Well anyway, I'm looking for a good alternative to hog's hair like ox hair or something. Any suggestions? What should I use? I don't want to use hog hair because I don't like/ don't eat pork and it just weirds me out to think of using a pigs hair to paint.