I am not a duck expert, this is only my first year with them, but I have done tons of research, a lot of which may be bogus! What I have found, is people feed all kinds of things and the ducks do fine. I keep males and females together and free feed, and was told the drakes shouldn't have layer feed because the drakes can't process the higher mineral and calcium content, and it can lead to organ failure in drakes, and shorten their life span. Now, since I am a newbie pretty much, I am not sure what info is right or not, but I feed a waterfowl food, and then have a bowl of crushed calcium for the girls, which they eat up. Again, like anything, you read all sorts of things, but in the end, it seems all kinds of food is fed, and the ducks are fine. I am just over cautious, and if it is reasonable to do, I try to do what I read is best, whether 100% true or not!