I open a can of mackerel for the molting chickens once or twice a week. Tofu with Poultry Nutri-drench is a favorite of hard molters that have little appetite. Occasionally, I give a seriously underweight chicken plain dry crumbles when she isn't finding fermented feed appealing.
There's a quirk chickens have. They get bored with their regular feed and see any alternative as a special treat.