I only have 4 girls left out of 10. They have not laid any eggs at all since the middle of summer. They are only 2 1/2 or so and I just can't find any reason for this. They look fine, nice feathers with no parasites. They have slowed down on their feed with less interest in scraps. We have a very nice coop with a roost and nice nesting boxes and it is very secure with good ventilation. The girls are buff orpingtons, which are my favorite breed, and all the others I have had have been healthy and usually lay until they die. Can anyone tell me what to do, or look for? I don't have any vets here that deal with chickens.