In september, I got my 6 sexlinks. they were a product of a broken home, and given to me by my sil. We didn't have much info on them, so I didn't know how old they were etc. They laid fine all through the winter, but since spring, I'm lucky if I get 2 to 3 eggs a day. Their calcium seems to be off, even though I am feeding them layer crumbles w(and I have tried three differnt kinds ) and give crushed egg shells in yogurt quite often. One hen has all of the feathers off of her neck, but nowhere else, (and she is my most frequent layer). Are they just old, is there any way to age a hen? Are their laying days over? If not, is there anything else I can try to help them?