Mine love Greek yoghurt. They especially love it when it is mixed though scrambled egg. I have tried this method of running warm water from the tap and placing the chicks butt underneath and gently breaking the poop up with my fingers.
http://www.the-chicken-chick.com/2014/03/pasty-butt-in-chicks-causestreatment.html
http://www.the-chicken-chick.com/2014/03/pasty-butt-in-chicks-causestreatment.html