I have fermented Purina Flock raiser and it never smelled sweet. And could get pretty strong after a few days (my husband gagged lol but it wasn't a rotting smell), I'm guessing that whats happened to yours. My experience with Purina Flock raiser was it smelled bad fermented. I now use Nutrena NatureWise and right from the opening of the bag it has a sweet grain smell and never loses it, even when fermenting. I like it so much better. I make a big bucket using the back slop method. The first time ever I fermented it for 3 days, now I use from the bucket until theres maybe a cup left, re-fill it with feed and water again, mix and the next day it's ready to be fed out to the chickens. Ive had no issues with mold or anything like that, but it can get stronger smelling as you reach the bottom of the bucket, especially if its hot out. You can certainly sprinkle a little dry over the FF but just make sure that's the only food you give them. They'll get hungry and eat it. I've not met a chicken that won't eat all kinds of crazy stuff when they are hungry. They just aren't used to it. I started my second flock right off on it and they come running whenever they see the bucket......unless they just decimated the flower bed and are full