We have three new ducklings. They are 2 weeks old as of Wednesday. I've noticed one having trouble walking starting at about 10 days old, and another not quite as nimble a couple of days later. Is there a leg weakness syndrome in ducks? The three are Snowy Mallard, Cayuga, Magpie. The Snowy Mallard seems completely normal in her gait. They were started on Manna Pro gamebird/showbird starter (24% protein), then I switched them to gamebird starter with 30% protein when I noticed the leg problem. This was the suggestion of the feed store owner. Any suggestions would be great! Thanks!