Until the government stopped it, some people here were feeding chicken droppings (which of course has wasted grain in it, etc) from poultry farms to cattle to fatten them. Of course, it might not be any worse than concentrates that you buy...
Sustainable Plantations and Agroforestry in Costa Rica
this is supposed to be a surprise, but it smells like a tiny ad:
permaculture thorns, A Book About Trying to Build Permaculture Community - draft eBook