Shell-less eggs becoming common

About a month ago, we started finding that we were often getting shell-less eggs laid in the coop at nighttime. Since four of my hens had just begun laying, I thought that it was just a little pullet mess-up and it would be back to normal soon. However, I have had many, many shell-less eggs by now (at least 10). There were multiple times when all four of the pullets laid a normal egg in the nest box after one of the hens laid a shell-less egg the night before, and there was once or twice when there was only one hen who didn't lay an egg after a rubber egg incident. This leads me to think that the one laying rubber eggs is our white leghorn Cloud, one of our three 1 year old hens. She's always been a little weird. Her poop has always been watery (except for cecal poops) and she didn't start laying until she was 8 months old. I'm worried she has egg yolk perontitis or something similar. Any opinions?

 

The only type of feed I can get without having to drive 1.5+ hours is Purina Layena pellets for laying hens. I think it's stupid that the feed is vegetarian, but I can't do anything about it. I have a one gallon feeder that I keep oyster shell in, but it gets buried in dirt all the time and the amount of oyster shell doesn't really go down at all. They do get treats. (which backyard chicken doesn't?) I try to limit the treats, but it's hard. About half a pie tin of treats a day, in which at least half are eggshells or crushed bones for calcium. This problem didn't come up for six months of my chicken-raising history, in which I fed a lot more treats; it just decided to come up a month ago. If I feel really tempted to give them a treat, I add water to a pan of normal feed and they go nuts for it.

ETA: Six months ago, I only had three hens, who shared that half a pie tin of treats. Six months ago, I got four chicks, and now I have seven hens sharing the same amount of treats.

 

I actually live in a suburb. Sorry that was unclear. Around here, (Silicon Valley) the only feed stores with good feed selections for livestock are all in the little rural towns.

I suddenly thought of something yesterday. I have one pullet who has never laid a normal-looking egg in her life. All her eggs have calcium deposits and darker coloring near the top. Could she be guilty of rubber egg-laying? Whenever we give them crushed eggshells, shrimp skins or crab shells, she always seems uninterested and doesn't join in the Grand Fight for Treats.

 

Thanks for the link! I'll consider it. However, it seems a little bit pricey. I think I'll do a bit more research on it.