I found this interesting article from ATTRA’s Organic Matters publication series. ATTRA is a project of the National Center for Appropriate Center for Technology in the US. Here's the link and an excerpt from the article.
"When it comes to organic livestock, hog production appears to be relatively unexplored territory. With few good guidelines or precedents to follow, it is useful to consider the animals’ natural behaviors so that the appropriateness of different housing options, herd management schemes, and so forth, can be assessed."
