My hens are 1 and 2 years old. One of my red stars has been laying brittle shelled eggs. They are also loosing their brown color and getting teeny hard bumps. I had a barred rock that did this last year and never went back to laying regular eggs. Sheeventually went to the stock pot. My chickens are being fed a very good feed, it is 18% protein. They have grit and oyster shell in front of them 24/7. The oyster shell is not pieces of shell like it used to be, this is little round balls.