Hmmm...I have my doubts the problem was a calcium deficiency. Hens lay lash and shell less eggs for many reasons.
In general, if the rest of the hens here are laying eggs with decent strength shells then their diet with regard to calcium is about right. They all eat much the same stuff and their size dictates the quanitity. The same applies to protein and fat. If you've got one hen carrying too much fat then the likelihood is they all are.
The hen stores calcium in a special type of bone. These bones are primarily found in the hens legs. What usually happens when a hen is severely calcium deficient is first the shells get thinner and eventually she suffers from osteoporosis.
You can find lots of information about this on the sites that deal with commercial layers.
Once again, in general, a hen doesn't suddenly run out of calcium deposits. It takes time. A sudden change in egg shell quality is usually another problem. I've never been quite sure why whenever a hen lays a shell less egg but shows no other signs of ill health forums such as this recommend calcium supplements. Unfortunatley the science behind egg laying gets forgotton and because after the calcium increase the hens next egg seems good the tendency is to believe that a lack of calcium was the problem. If a hen cannot produce any calciuim or that little then she would have bone related illnesses. Lots of battery hens used to get osteoporosis when I worked on my uncle farm which was before more was known about diet and how the hen manages her calcium supply.
I’ll look for a compromise.
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