All the calcium that a hen uses in the production of egg shells is first withdrawn from her skeleton. Feeding oyster shell is only intended as a replacement source of calcium needed to refortify or rebuild the hens' bones. What no one ever considers however is the effect of vitamin D or especially vitamin D3 on the health of their hens. Without vitamin D3 neither a hen nor a human can properly utilize the calcium in their diet. Without sufficient vitamin D3 it is possible for your hens to develop a condition known as hypocalcemic tetany. To learn more about this condition or vitamin D follow through with the link below. Excess calcium especially in the young can result in deformed skeletons and other problems. The sole source of vitamin D3 is from animal protein, even the vitamin D found in fortified orange juice.
http://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
"Vitamin D promotes
calcium
absorption in the gut and maintains adequate serum calcium and phosphate concentrations to enable normal mineralization of bone and to prevent
hypocalcemic tetany
. It is also needed for bone growth and bone remodeling by osteoblasts and osteoclasts [
1
,
2
]. Without sufficient vitamin D, bones can become thin, brittle, or misshapen. Vitamin D sufficiency prevents rickets in children and osteomalacia in adults [
1
]. Together with calcium, vitamin D also helps protect older adults from osteoporosis."
At the bottom of the above link notice that egg yokes are a good source of vitamin D3.
If you can't find certified organic oyster shell in your feed store you can make your own at home. To make organic oyster shell you first must catch an organic oyster. Because the word "organic" means "Based on the element carbon" all oysters are organic because of the thick calcium carbon-ate shell surrounding them. Because organic oysters lack eyes to see you with, and both feet or legs with which to runaway from you, it is not difficult to bag an oyster. The next step is separating your oyster from its organic shell. It helps if you love
eating raw oysters, or oysters cooked any way for that matter. I love them so well that one time I got very good at evicting oysters and you will too. After you have evicted the unlucky mollusks from its digs, what you have left is 100% pure organic oyster shell, waiting on the hammer mill or rock crusher..