It's a myth that egg shell is not sufficient. If fed in adequate quantities, it is sufficient. Calcium from egg shell is absorbed just as well as that in OS. The issue with egg shell is this: if you are only returning egg shells to your flock from the eggs that they lay, then you will reach a point of diminishing return. But, if you have a safe source of egg shell, then it would be an adequate substitute for OS. I can believe that someone who is alergic to oysters may very well have a reaction to the OS in feed, or OS supplementation.
I have a friend who is highly reactive to gluten. Simply being exposed to the dust in a bag of chicken feed will send him into a reaction. I am allergic to scallops. The reaction caused by them is immediate, and includes digestive as well as cardiac responses.
For the poster who is allergic to OS, what about doing the math, and providing Ca++ from calcium pills?
I'd love to hear someone with experience using limestone as Ca++ supplementation. What is "high quality" lime, and how much would be used, and how would you use it?
