Our birds went through a tough moulting this year, I've never seen such a thing until BYCers started posting pics and my girls were mild! (thanks guys), but while moulting, I feed a feed with higher protein and fat so that they would have the energy to grow new healthy feathers. They most certainly did at that. Still, they are not back to laying yet, if lucky we will collect 2 eggs a day.
It really takes a lot of energy to go through it, almost like how our bodies heal from a surgery, the feathers don't hurt as long as they are not pulled or pushed, then it appears to bother them. Also, they will seem depressed, shy away from everyone almost embarrised.
But, now my girls are fully feathered, winter coats on, they are happy, healthy and vibrant!
Good luck to you and just give them some good wholesome foods, yogurt, fruits, veggies, sprouted wheat, oat +rye seeds(human quality!), they love it and it will help give them nice vitemans.