I have started using DDG as it is cheaper than corn here and has more protein in it, but you still need a good protein supplement like soybean meal or fish meal with it. I have used up to 15% of the ration as DDG with no problems. The birds don't seem to care and eat it fine. Be sure when buying DDG that it has not been burnt in the drying process. They should be a nice light brown color, a little darker than a manilla envelope. If they get darker than say, cardboard, they have been over heated and burnt. DDG should also have a pleasant sweet smell to them. Hope this helps.
DDG can be bought at just about any feed mill. You won't find it at a feed store. It is but one component in a complete mixed ration. Feeding just DDG and a few scraps of fish, meat and bugs will not work. The birds will not eat DDG straight up (at least not much of it), it has to be mixed to be eaten well. Like I said, 15% maximum in the ration, even Tyson will not go higher than this and they always use a lowest cost ration formula. Everyone always looks at the protein number, but the quality of the protein is also very important. DDG is 25% or so protein, but it is only so-so quality, deficient in lysine and a couple other amino acids. When you feed protein you are really feeding amino acids. If they are not present in the correct ratios it doens't matter how high the protein content is, the birds will not be at full potential and can even die. That's why feed has things like soybean meal, fish meal, etc. in them - to balance out the amino acids and increase the protein. Of course, if any of the ingrediants have been handled poorly in production it can also degrade the nutrients. You have to shop carefully for feed ingrediants.
What about feeding it fresh? My DH brews his own beer, can we give them the mushy stuff that's left? It's not fermented at that point, so the chirps won't get drunk! Would there be any harm in giving it to them before it's dried? and what's the best way to dry it myself?