Shell-less Eggs Are Suddenly Appearing

[LeastinID]

We have & chickens, 4 20-month old EE, 2 8-month old White Leghorn and 1 8-month-old RI Red.
The 3 youngsters have been consistent in their egg-laying.
The older hens have endured their 1st molt and are now getting back into production.
All seemed to be going well until . . .

The weather turned downright nasty- snowy, windy and quite cold which lead them to choose to stay in their well covered run.
About 5 days ago, I discovered a frozen shell-less egg which had been pecked at (see attached photo).
2 days ago I discovered 2 partially frozen shell-less eggs.
This morning, as I approached the enclosure, I heard a very persistent tapping.
I opened the chicken door and only 5 hens came out and the tapping increased.
I peeked inside to see another shell-less egg being assaulted by the remaining 2 hens.

To quote Slim Pickens,"What, in the Wide World of Sports is a-goin' on here?"
Since the young'ns have been consistent in their production, I'm pretty sure the shell-less eggs are coming from an older hen (older hens?)
After their molt, does it take a while for the chickens to get back into the swing of producing a good shell?

 

[BobStuart]

Lack of calcium it must be. What do you feed her?

 

[LeastinID]

Lack of calcium it must be. What do you feed her?

All the girls have the same food source, and we always have crunched up eggshell available.
Recommendations are more than welcome!
Without knowing who's dropping shell-less eggs, any supplement would have to be in either their water or feed.

 

[BobStuart]

All the girls have the same food source, and we always have crunched up eggshell available.
Recommendations are more than welcome!
Without knowing who's dropping shell-less eggs, any supplement would have to be in either their water or feed.

Do you feed them laying feed? Maybe switch brands for a bit. See if it changes.

 

[Wyorp Rock]

About 5 days ago, I discovered a frozen shell-less egg which had been pecked at (see attached photo).
2 days ago I discovered 2 partially frozen shell-less eggs.
This morning, as I approached the enclosure, I heard a very persistent tapping.
I opened the chicken door and only 5 hens came out and the tapping increased.
I peeked inside to see another shell-less egg being assaulted by the remaining 2 hens.

Are you finding any shell around the frozen eggs? You sure they are shell-less or have the hens already picked the shell and ate it before you discovered the frozen egg yolk/white.

Even shell less eggs usually have some type of membrane around them.

If you are feeding a nutritionally balanced layer feed, you really shouldn't have to switch feed.
Do provide oyster shell free choice for your girls. You can find it at most feed stores.
You can still give them their egg shells back too.