TSC usually carries Purina duck feed. if you are going to keep your ducks separate from any other poultry you have. I have ducks chickens and geese so I feed NON GMO poultry feed and add Nutritional yeast for extra niacin. Even using waterfowl specific feed young ducks need the extra niacin. And Pekins may need it all their lives. The liquid B complex will say injectable but we use it orally if your duck has a special treat she'll gobble down put the liquid B on it just enough treat that she'll eat it all and get full dose.