Thanks for the info. When my neighbor saw my hen who didn't look right, it was 5 in the afternoon that hot summer day. I suspect she may have already died by then. She was in the same position the following morning, and that's when he knew she was dead. I think he said her head was down and she was on her right side. It may have been heat stroke. Who knows? It is haunting not knowing. I ran the weird egg by a poultry expert when it happened, and he said it might have been a freak thing and that if it happened again it might be a sign of an internal disease/infection that would kill her. It never happened again, and I had thought we were out of the woods. But she had panted harder all summer in the heat than her sister, and I suspect the feather picking was a clue to something-- probably fatty liver disease, but I never could figure it out. I'm glad your hen's egg came out. One thing is for sure-- I'll never give my girls scratch again.
Hatchery broiler type chickens are bred to put on too much weight to be healthy. I don't eat chickens. I keep them as pets, so rationing food is important, I think. Otherwise they gorge and get fatty liver disease which leads to stuck eggs, etc.