We have 3 week old ducklings and one of them is showing signs of (what i'm guessing) a niacin deficiency. He has a really hard time walking, when he does walk he fumbles a lot and cant stand up straight. He walks in zigzags and looks like hes's drunk. He spends most of his time sitting while the rest of the ducks are walking around being a lot more active. He is also a lot smaller than then rest of them. He also is unfortunately getting stepped on sometimes by the other ducks because he cant really stand up and move as fast. Can just one single duck out of the flock suffer from a niacin deficiency or would I see symptoms in all of them? Is there maybe something else wrong? Any info will help, I am new to this whole duck thing! Thank you!