Yesterday one of my Rhode Island Reds laid an egg about as big and round as a quarter (a fart egg as some would call it), and today I had a normal sized soft shell egg. I have been feeding my chickens Purina Layena Pellets w/oyster shells since they were 18 weeks old (they are almost 7 months now). I have had fart eggs and shell less eggs in the past, but I chalked it up to them being pullets. And, I have had days and weeks where all 7 of my hens gave me great eggs. What can I add to their diet to help to prevent any more of these small and soft eggs?