Once a week every Monday our pods have one day without eating meat. That day our girls get eggs yolks. I am a supporter of the natural, separate diet, so even with dogs meal I don't mix anything. This kind of meal gives us the opportunity to give our body full of vitamins and minerals. I give eggs yolks completely separately, as a dish for supper. I put eggs into a boiling water for one minute, next I put them to cold water. I spill egg white to bowl and I leave it for us. Our lovely pods get yummy eggs yolks high in vitamins. I leave also eggshells to dry. I put them into a glass and cover some gauze (to close access for insects). You can also put these eggshells into a paper bag. After a few days (3-4) dry eggshells are ready to mill. I use stone mortar but if you want to make it faster you can use coffee grinder. It's good to use eggshells every day, with a meal. Our pods get one teaspoon of eggshells every day (not in days when they have bones with meat).