I have 8 girls-two leghorns, two orpingtons, a bramah, a production red (I think), a cochin and a mutt. This will be my second summer with them- and they came to me as mostly adults last march. They all free range almost daily, for several hours in my stone/dirt driveway and the leghorns actually free range more than the others because they tend to get out without my help. I offer oyster shells at all times but have gotten lazy about the grit since they have access to my driveway and very rocky soil. I have noticed over the last month or so- at least three or four days a week one if not both of the leghorn eggs is cracked. Not large spoil the egg crack- but when I wash them I see it. I put them in the bin in my fridge that is for me- and when they cool back down the cracks are barely noticeable and I have eaten several of the eggs and they are fine. I just don't understand why its just the leghorns. Could it be an age thing? They are probably going on three years old if the guy I got them from was honest. Would I see changes already>?