I noticed that no one had commented on this
thread, which is sad because it provides some very useful and accurate information (just follow Walter's link)
I've been making our own yogurt for our family for many years. I don't own pigs, but I can't see any reason why they wouldn't benefit the same way we do from the healthy effects of eating it.
I read Walter's link, and everything seems to be a reasonable and simple way to create large batches of yogurt.
Yogurt can be made from any kind of milk from raw, unprocessed, milk to pasteurized and homogenized skim milk from a grocery store. I've even made it from powdered milk, just to prove I could.
This allows you to tailor the fat content and also allows you to use whatever is available or your budget can afford.
I agree with Walter than the multi-cultured yogurt tastes better and seems to work better, but you can make yogurt from a single culture. The easiest way to start if you don't want to find special cultures, is to buy a "live cultures" yogurt from the store. It will work just fine as a starter.
Home made yogurt tastes great and is far less expensive. In large batches it cost pennies a serving. Exact cost is dependent on the ingredients you choose, of
course.