Some mash goes direct to the farmer and is fed wet. I'd stay away from it, it rots teeth. Cattlefolks here are finding out!
Some is dried, and this is good to use, as I said, depending on cost for protein and tdn compared to other feeds.
Aflatoxin is not a huge problem for distilling, so no troubles there. They'll take it. I would imagine the process will kill it, as it involves heat.
I actually read yesterday about a meat goat farmer successfully feeding 50% chicken litter and 50% grain to his Boers. So what is economical and acceptable to the goats is only limited by our own minds. I feed mine browse, grass, hay and cottonseed, in that order. The cost increases in that order, and the amount fed decreases. They get nothing but browse and grass 7 months a year. Even in the dead of winter, they are limit-fed the cottonseed to what they can eat in 10 minutes.