I called a feed rep. and asked why the instructions on the bag of layer pellets insisted it not be fed before the birds were 18 weeks old. The answer was if the bird was not mature enough, being on the layer too early could cause some problems. My Australorp obviously was one of those late maturers and also had gone through moving to a new place and heat stress. She molted out her neck feathers, which I've read is directly related to the too-early feeding of layer feed. I believe all this has stalled out her first egg. She's about 5 1/2 months old now, which is certainly not old!, but her sisters at the seller's house were laying weeks ago. Love the birdie anyway.