I feed out spent grain at a higher rate than 2 ounces per day. The chickens get a small dab of layer pellets am and pm, like 8 cups, and free range the rest of the time. I am using it to fatten up broilers, give some to the youngest chicks successfully, and all are thriving.
I am getting about 150 gallons a week and am going to start drying some on old window screens so I can have some in reserve, just in case. FYI, I also feed it to goats, sheep, and horses with much success. The rabbits either love it or hate it.
It's a great resource!