I don`t want to start any controversy or seem a little harsh. But the eating of halaal was never mentioned in the Granth Sahib, and it should not be justified that is what our religons asks us to do. In essence every animal suffers when we kill it, and modern day way of killing an animal is much worse than the way Muslims kill the animal, and pray. Our religion teaches us to be tolerant. Guru Nanak traveled and ate everyones food, and their meat, meaning he tolerated and accepted ways of other people. Why should we make rituals in order to justify what we would like.