Depends on the question, doesn't it?
I'm vegan because the workers in the blood industry suffer both workplace related and psychological trauma from working in slaughterhouses. Not only are they treated badly by management, but being surrounded by so much suffering and death actually causes incredible psychological harm to the people forced to do this kind of work. Killing always takes a toll on the mind because we're empathetic apes - on an industrial scale it's simply inhuman.