Hi Kathy, Thanks for your comment. I appreciate you pointing out the eggshell quantity does matter, you are most certainly correct. In much of the cited literature, the most important thing to be concerned about is feeding your hens a professionally balanced layer feed at free choice, much of the calcium they need will be supplied there. That is why I was very clean in the beginning of the post to point out that you should always supply a purchased source of calcium for your hens if you are not feeding a balanced layer feed. Additionally I pointed out that if your hens eggshells are a little thin, supplementation other than eggshells will also be necessary to prevent problems. It's also important to note that even with oyster shell supplementation or other forms of supplemental calcium, hens will still draw calcium from their body supplies. (Basics of Animal Nutrition and Feeding (Chapter 26), 5th edition, Pond et al., 2005). Thanks again for stopping by!

Yours in Poultry,
Kathy Shea Mormino
The Chicken Chick®