I would say 28% is way to high..I was only feeding 20% when my duck got angel wing...I wrapped him for 3 days and cut the feed back to 15% and feed lots of greens to keep them from eating to much feed...It worked..He is back with the others cant even tell...From the pic I saw it does look like angel wing...
Here is what mine looked like...
Here is what mine looked like...
