I can't seem to find any information on this topic anywhere online, I am looking for a little advice. My husband and I left on vacation for four days over this past weekend. We left our five hens (they are all of laying age but not all are laying yet) in the run while we were gone. We left them enough fresh water for two weeks with a nipple system. We also have a feeder that will hold enough food for a week. They didn't end up getting their feeder filled before we left because we each thought that the other had done it. I texted our tenant and asked him to feed the hens. Was very specific about how to do it and where to find the food, but he has a few learning disorders, is high functioning autistic we believe. When we came home last night I saw that their feeder was mostly empty yet had about an inch of some white substance. To my horror I realized that he had filled their empty feeder with Oyster Shell rather than their layer crumbles. They ate nothing for four days but oyster shell and they went through their entire two week supply of water. I am amazed that all five of them are still alive!! I am worried about liver or kidney issues. They were all bright eyed and active this morning when I let them out to free range. Does anyone have any advice as to what I should keep an eye out for with them? Or any supplements I can give them to help regulate levels? Thank you in advance!