are chickens born with defective shell gland or can it develop over time?

[chitownhens]

How were/are you applying this.....pilling, mixing in feed..??
What dosages?
Any Vit D?

a 1/4 teaspoon to about a quart of water which is a little over 700 mg basically one avg size calcium tablet. No vitamin D but now that you mention it I will add a spray of some that I have for human use.

I have also used half tablets of crushed calcium sprinkled on to a watermelon slice where it dissolves into the pulp.