My adults are just a year old and I have not noticed any problems with the higher protein. My ducks gets 2 cups flockraiser and 2 cups layena everyday mixed together. Sometimes they eat it all and sometimes they don't. My ducks are extremely active and spend the majority of their time foraging...
I take away the overnight food at 4 weeks of age but they always have water around the clock as ducklings. My adults also have water buckets in their houses at night.
Yes I think they would be ok, just make sure to make any diet changes gradually.
I added layena to the flockraiser when I started to get eggs. The geese get more flockraiser than layena because they don't like the layena very much. The ducks get about half and half. I do this because I have...
I also use flockraiser for my ducklings and goslings without adding extra niacin. For my chicks I am using medicated chick starter and will switch them to flockraiser when they are 6 weeks. It is a pain to buy separate feeds but the best start you can give them the better. Everyone gets some...