Spiritually the only real sin is the illusion of seperateness. The idea that killing something is inherently wrong comes from a presumption that life is somehow better than death, and that life is something opposed/seperate from death. Have you ever seen life without death? Have you experienced an inhale without an exhale?? Why is it permissible to give life, yet not to take life? Is the death of the body not just the release of the soul? Does the loss of that life somehow make the universe less whole?
The idea that one must try to stay alive is what takes the life out of living. To live fully; be thee animal, plant, insect, or fungus one does not hold onto the thought of keeping death at bay, such a thought keeps one where one is not instead of where one is! If you do not believe death is evil then you can take life with love and compassion. Ultimately it is the intention behind the act that determines whether it is born of sin or not. So if the act comes from a place of love and not fear then it is in line with the unity and therefore not sinful.
That being said, I believe that the reverence has been by and large forgotten, and that goes for everything! The way everything is treated on this planet right now is pretty horrid, be it soil, mountain, stream, insect, fungi, animal, plant, whatever it is!
All that to say that I see no inherent sin in killing, and consuming. Nor in being killed and consumed.
The Space Monk-€-Nigmatron