One potential problem with feeding chicken grower to ducks or other water fowl is that it may not have enough Niacin. Waterfowl that don't get enough Niacin are prone to leg problems. Tractor Supply starter is supposed to be formulated for both chickens and ducks, but there is probably a lot of chicken feed out there that isn't. A lot of duck owners here say they supplement their diet with brewers or nutritional yeast for Niacin.
