I have 2 ISA Browns, 2 New Hamp Reds, and 2 Silver lace Wyandottes, all bought at the same time and age this last spring. Only one of the ISA Browns is laying eggs and has been for about 10 days now. They are getting egg laying feed, scratch grains, and many veggy scraps as well as bugs and plants in the yard. They get locked in the coop at night, penned up in an enclosure during the day when no one is home and free range in the fenced in yard when we are home. Why have the others not layed yet? Is there anything else I can do to encourage them to start?