Hi everyone! We just picked up some ducklings that needed a good home. There is one I am concerned about. He is apparently about 4 weeks old and seems to have a bad leg. He gets around ok but not as easily as the other 2 we got him with (all the same age). The leg does not seem to be painful, only his left leg is affected. We are fairly new to ducks we have 4 khaki females that are just over a year old and we haven't seen anything like this before. From the research I've done online it seems like maybe he has a niacin (B3) deficiency, I'm hoping someone can confirm that's issue or point me in the right direction. The people we got him from said they noticed his leg was bad but didn't know of any trauma that would gave caused a fracture or injury. The leg is held away from the body and the foot is rotated inward.I appreciate any help and information that you can offer. Thank you! I have attached 2 pictures of his left (bad) leg.