My 2yr old hens have abruptly stopped laying after quite a few of them had already started laying for the year. We went from getting six eggs a day out of seven hens to absolutely nothing for two weeks. We do free range them, but we've left them locked up in the coop for four days during a cold spell and still no eggs.... Do you think that it could be due to stress? I've never seen anything bother them during the day, and they sleep inside a very predator proof coop at night, so I am at a loss. Thank you for your time!