They Free range and eat bugs, if they act hungry when I shut them in at night I give them chicken layer pellets (I know that can also cause problems too, we don't give it to them as ducklings)
My one duck (a call duck crossed with khaki Campbell, I think? The person I bought her from said she was khaki, but she's way too dark and looks a lot more like a call duck) Has been limping for about a month now. She kind of stands on it, but she walks low to the ground with it out to the side...