I've had good luck feeding spent-grains to pigs...I actually use if for all the animals. I find that it stores much better without getting too "sour" if you drain it. I get it in 55-gallon drums, and when they had a hole in the bottom and could leak out excess moisture, it stays "sweeter" longer.
I've had good with the sbg up to 50% or so. I feed lots of sweet potatoes as a carb replacement. The easiest was strip grazing the pigs across the sweet potato pasture and letting them do the harvesting. I also add some kelp and conventional feed at times. I also feed scraps from the house and a restaurant I sell to. They keep the scraps refrigerated so I don't pasteurize it. It only lasts a day or two, but I figure it gives them some nutritional variety. I also feed excess milk/yogurt from my cows...which usually isn't much.
I'm working on planting out some "pig-fattening" paddocks in the next few weeks....lots of sweet potatoes and jerusalem artichokes, and I'll mix in extra garden seeds, sorghum, etc. It's all in an old pecan orchard that will hopefully produce in years to come. I also plan to add some apple, pears, and chestnut trees, but I will have to figure out a way to keep them protected cheaply. good luck!