I've been against animal rights and related ideas/movements for years.1. You can love animals and still eat meat. Saying otherwise is like saying "You can't have morals and be an atheist." It's disgustingly generalized, and I'm sure you can pick out many exceptions. I'll give you one - me. I love cats and dogs and have spent five years studying dog training. I am for animal welfare, but not animal "rights."
2. It's not "proteins" you need to worry about. It's getting enough animal proteins and vitamin B12. Animal proteins are part of what we run on and B12 helps with brain development (or something related to neurons).
But all-in-all, it's your life, do what you will. Just whatever you do, don't be moved by graphicly violent PETA-esque ads. Things die, big deal. Chances are it looks worse than it really is, like Kosher slaughter. When the animal's throat and jugular are slit, the blood loss is so rapid they lose consciousness almost immediately.


