I have been both sprouting and fermenting whole grains for over a year and have never had a fermented grain sprout, ever. As to whether you could ferment an already sprouted grain I have never tried that and do not know.If you are using whole grains when you ferment the grains will sprout while you are fermenting them. The trick is how sprouted do you want them. I use a large quart size jar and put two tables spoons of seeds (varied seeds a bunch of different ones) in the bottom and soak them the first day and then I will let them grow for up to a week after that to get good and long before I feed them. I have heard that sprouting the grains will increase the vitamins and minerals in the grains. And the chickens seem to love them.