My girls free range and get most of the nutrients outside, but I want to give them oyster shells. Do I put it in a container next to the feeder in their coop or mix it with their pellets? I just got my first egg yesterday (finally) and will recycle the eggshells back to them, but for now don't have the shells to give. Also, my other girls haven't started laying, but should very soon (they are 19 and 20 weeks old), so will it harm them if they consume the oystershell I am leaving for my one layer? I would appreciate any input!