Butcher in the family.

My mother and I have close relatives who are farmers and raise a large number of cattle for slaughter; they are convinced that what they are doing is truly good for the animals—that it constitutes good animal welfare. Most of the cattle graze outdoors, though they are transported elsewhere for slaughter. Additionally, they bought two pigs for their children, intending for the kids to learn how to earn money from them when they are eventually slaughtered. The pigs are kept indoors because the farmers don't want them wallowing in mud and subsequently getting sunburned; they believe this is what is best for the pigs as well.
We don't want to get into an argument with them, as we disagree on *every* point. We know they do this because they grew up with it—it is their entire life and livelihood. We need advice on how to handle this situation without losing some very close family members.