I just moved my ducklings into a bigger cage. I just noticed that one of the Pekins that I got about a week ago can barely walk. I'm sure it's a niacin problem, but I've been adding 5-6 NaturVet Brewer's Dried Yeast Formula tablets to approximately each pound of food. The bottle says that each 500 mg tablet has 0.500 mg of Niacin. There are 6 ducklings. Should I be giving them more. Please help me. This is my first time raising ducks, and I really don't want to lose one of my babies. The one with the problem also has a pale pink bill while the other one has an orange bill.