After some research I found that game bird feed works for ducks. I have had my ducks on it for more than a month with no problems, and they seem to like it. Though ducks do seem to like most everything. Most feed stores will have the game bird feed, I use the purina brand.
I don't actually have any chickens. I do have 10 ducks, 8 Rouen, and 2 Harlequin Welsh. I also have 12 Jumbo Coturnix quail. We were going to go with chickens, but we were worried about the noise, then after getting the ducks we found out my neighbor had some, so now we will have an egg...