Many products that are used to condition hens for breeding, such as wheat based ones, must be used carefully as they tend to encourage the hen to promptly lay eggs, often prematurely, which results in many infertile eggs.
Recently, when I started my birds on Calcium gluconate 23% solution (1 tablespoon to 1 gallon water used daily in the water till breeding season is over), I noticed what a positive effect it had on the birds coming into condition naturally rather than prematurely. All the birds became more active and when I check the hens abdomens they were becoming bare and red and felt much warmer. When hens lay prematurely before they are in condition, laying is out of sequence happening before their abdomen are bare and hot.
The positive effect of using this product in the condition process makes good sense as having calcium available communicates to the hen that conditions are favorable for laying eggs as well as the effect of calcium on reproductive hormones.
Extremely high blood calcium levels are necessary for laying hens. When a bird lays in the morning hours, like canaries, when food intake and subsequent intestinal absorption is decreased, bone calcium is mobilized from the calcified medullary space of the long bones particularly the femur and humerus, which was stored primarily during approximately ten days before egg formation. If calcium is deficient in the mobilization process it can result in reduction in FSH secretion and thus can even stops the laying process.
An added benefit of shells with proper thickness is increase fertility as when eggs have the proper thickness they develop and hatch normally rather than dehydrate.