It all depends on how bad the problem is. I had one with wry neck that took two months to get fixed finally. But the Rouens I had I saw improvement in their legs in a week but they hadn’t gotten to the level your baby is because they were smaller when it started.
Between rest and good vitamin...
I provided it for bigger ducks regularly. But my light and little ducks I do it only a few times a week when they are young unless they show injury or problems. But I feed nature wise which has a higher niacin content.
I would try to keep the weak legged baby off it’s feet as much as possible. Use swimming for exercise like @Miss Lydia said plus epsom salt soaks. Don’t let it drink the epsom salt water. Also try to make sure the injured one is the one getting the 1 ml a day for sure. Usually if you can get...