Since your feeding starter are you supplementing with any form of niacin chick starter doesn’t have the amount of niacin water fowl need for strong legs and since both your breeds are large breeds they really need it to be able to carry the weight. I'd start by getting some liquid BComplex TSC has the best it’s in the cattle dept it will say injectable but you can peel off the foil and use a 1 ml dropper and start giving this daily to your little Rouen and your Pekins too. Put it over something they really like. I think I’d do your littleRouen separately to make sure it’s getting the full 1 ml. It’s amazing what it can do. Pekins are such good a eating are you sure this little one is getting enough to eat? This is what your looking for I understand it has a new label but it’s exactly the same contents .
View attachment 1798050 If possible I would also buy an all flock for your ducks it is formulated for all poultry and will meet the nutritional requirements your duckling need.
