Giving shell to chickens

Your hens should self regulate their calcium intake, though they could be eating the shells for the protein in the membrane. I use oyster shells, but will also toss out the egg shells on occasion. I just dump mine on the ground and step on them to grind them up. Chickens don't mind dirt as long as it isn't poopy dirt. You might want to switch to oyster shells for now, and use the eggshells as an extra source of calcium after they are laying.

 

Egg shells are fine, but go thru pretty fast for only source.
Oyster shell will stay in gizzard longer for better absorption.

How much they use and eat may depend on what kind of feed your providing.
I use a high protein - low calcium feed, so they gobble them up.

I rinse, dry, and crush egg shells and mix into the oyster shells.
This is how I put them out....these pics have no oyster shells added:

 

This is what I do....I rinse out my shells and dry them on paper towels...I have people I sell my eggs to too also do the same...I only use the shells from my hens...I crush them and mix with the oyster shell...I have a two sided wall mounted feeder hung at hen height..One side is grit the other is oyster shell...When I have enough egg shells I add them...They will only eat as much as they need....

Hope this helped?

Cheers