Not sure if this is helpful in the context of permaculture, but offered for what it's worth. My dad used to be a treasurer for a large commercial brewery. They sold their spent mash to pig farmers. At a certain point, they decided to buy a string of breakfast restaurants and the pigs to supply them because the mash was such nutritious food for the pigs, and they had essentially unlimited access to free pig food. My point is that it's good food, and economic at the commercial level.
