1) If you’re that bothered about animal welfare, why are you eating at KFC?
2) If you’re not religious, or you are of a religion which is not Islam, why are you bothered if someone recited an Islamic prayer over the animal as it was killed? If you don’t believe in Islam, why does it matter to you? To you, those prayers would just be meaningless words. As an atheist, I wouldn’t care if prayers from every religion the world has ever known were recited over my dinner, any more than I would care if someone read passages from The Very Hungry Caterpillar.