I am not a vegan; I have some friends and acquaintances who are. I think that part of the moral issue is that cows do not surrender their milk willing and are made to live uncomfortable lives. However, I would venture to say that when you injest somebody's semen, there has to be at least some level of consent, even in "forced" masturbation scenes and that any discomfort on the part of the donor is temporary, and likely even desired . . .