I'm hoping others will chime in here, but I know that chickens will molt when it is a different season, under stress, or because of parasites. I would switch all of my chickens to a high protein diet, but still keep out the regular feed if you feel it necessary. If your chickens are molting for seasonal reasons, then all of the will molt and grow new, shiny feathers that look better than before! They will look a little patchy for a couple of days or weeks, and they may stop laying for the molt, but they usually only do this once a year, and their feathers will be better than ever when they are done molting!