I just got 2 indian runner ducks almost 2 weeks ago from Metzer farms. They both eat and drink and get around well, but one of my ducks has bent legs which causes her to bend over. She still gets around well but is a little more clumsy then the other. I am expecting to get their new feed on Tuesday this week, which is a duck grower feed. Right now they are on New country organics chick starter and I give them brewers yeast in their food and water. Even though I have been giving them brewers yeast since I got them, could this be a niacin deficiency? Please let me know your thoughts, I will attach pictures!