Roy Kirkwood & Phillip Thacker 
Non-Traditional Feeds for Use in Swine Production (1992) [PDF ebook] 

Feed represents the single greatest expense associated with bringing pigs to market weight. Therefore, if you can reduce the cost of feeding without detriment to pig performance, the economics of swine production will improve. The ingredient list for swine rations has become fairly limited, and the majority of diets fed to pigs consist of a few staples, such as corn, wheat, barley, and soybean meal. Non-Traditional Feeds for Use in Swine Production explores over fifty non-traditional feedstuffs in terms of their nutritional content and their viability as alternative, cost effective food sources