I moisten the feed and add a little apple cider vinegar to it. You do not have to ferment the feed for days either. I tend to make mine in the morning about an hour before feeding time. It swells a LOT so cover the feed to be given with about 1/2 inch of water then let it sit. I also only give them enough of the wet feed that they can finish it within about an hour. We are getting freezing temps so that way it gets eaten before it can freeze.
Cooked rice or oatmeal will also encourage them to take a bite. Don't panic to much they will eat eventually usually.
Cooked scrambled egg is a good suggestion too. Mine also go nuts for canned mackerel.