Winter molts?! I swear they choose to do so to drive us crazy sometimes. I've had it happen before with some of the rocks and brahmas I had.
I feed 20% normally unless the store has the Egg Producer in? Then it's 21%. I do give them cat food fairly regularly during molt. It's a treat the rest of the year unless you're the old lady who knows where the cat bowl is and will sneak in the house if she can.
I do mix in game bird starter 30% if everyone is doing a heavy molt. Usually half and half for a month. None of the birds I have now molt like that. Actually I've never had a silkie or ameraucana do it.