what is ddg? never heard of it...

There are two big beer breweries here in Colorado, Coors, and Budweiser. I know the feed stores up in their area buy and bag the distillers grain and sell it in their stores. I don't know what percent protein, etc., they have. I know of people with market goats that routinely feed it, but am not sure about dairy goats, since they require a higher protein level. I have also heard of market goat people going to the smaller micro breweries and getting the grain "wet" from them. Most of the smaller places give it away, as it is problematic to try to store it and dry it for resale. I would think the wet stuff would have a short shelf life, as it could grow mold, etc.

i left some in their bags overnight and they smelled wretched the next morning. but they must be sterilized by the distillation process or whatever -- i've seen them piping hot sitting out in those barrels!

The brewing process does not sterilize the grain. It sanitizes it, but its still highly vulnerable to fungi (any antifungal would stop the yeast from working on the wort, the sweet water boiled out of the grain). If you dry it quickly nothing will take off in it in a major way, most of the water 'loving' (hygroscopic) simple carbohydrates (and almost all of the carbohydrates are simple because of the malting and mash processes) are rinsed out of the grain (lautering) because they will be fermented into alcohol.

Its though stuff to digest, lots of cellulose, but I'll bet that goats can handle it, I wouldn't make it the full diet, diversity is key.