If the issue is how the animal is treated, as opposed to the strict moral issue of taking its life, organ donation wins over food production every time. One of the animal rights lobby's strongest talking points is the horrible way in which food animals are raised. The animals raised for organ donation live a much more comfortably, much more humane life.

Animals feel pain and are capable of suffering; I get that. So causing them to suffer so our food can be made cheaply seems right. But their lives, on their own, don't have the moral weight of a human's, so if they are treated well and killed painlessly, I just don't see the problem. Especially if killing a pig saves a human life.