I have four 15-month old hens that several months ago had pasty butt. I put DE in their coop shavings and added a bit of garlic to their water. I removed all the poop stuck to them and clipped the affected feathers. The feathers grew back and the pasty butt disappeared. I still have those hens, plus 9 eleven week old chicks. The pasty butt has returned, but it is only affecting the 4 original hens.They all share the same quarters, eat and drink the same stuff. What causes pasty butt? Why are only the hens affected? Any suggestions for getting rid of it? They all appear to be otherwise healthy and have voracious appetites - at this time of year they are eating a lot of greens and fruits. Does diet make a difference?