I have a mixed-age and mixed-species "flock" (only 3 little ones). I have a 4 week old Cayuga, 2 week old Rouen and just about 1.5 week old Embden. Is it about time to change their food from chick starter? If so...what now? Just adult "waterfowl feed"? Do I need to supplement with greens/peas/oats/niacin? Thanks in advance! Newb here and just want to make sure I"m doing all that's necessary to raise 3 healthy babies!