Hi David.. and this is an issue that can and will go on for eternity. It's true to say that in "effect" we are all killers to some degree. The natural food chain that we are all aware of ... As an example will never cease. As Altair says... Even if one is vegan , we still feed our pets with food which comes from that chain. I would even go as far as to say even picking and eating nuts is "killing " something . It's all a fine line. Otherwise we would eat nothing and all perish. On the other scale, there is a difference between killing something and keeping something that is alive , in captivity to live in abject misery.