To cut down on waste of your oyster shells I would feed the shells separately. Chickens love egg shells. I usually just dump mine on the ground. I don't bake them either.
I wasn't baking them but they seem to be much easier to crunch up when baked...I usually just slide them in the oven after my wife bakes something and leave them until it cools down.
I usually set the eggshells out in the sun for a couple day and they get crispy.
I found when I rinsed the insides they crunched up easily (after they dry in a bowl too) without the egg whites acting as a glue and sticking egg bits to my fingers.
People have used whatever has been available to them. My grandma didn't even know what an oyster was
That's a whole lot of work! Why do you rinse them? And why both dry and bake? Seems like too many steps to this process. And why crush them to a powder? The chickens need to be able to see and identify the eggshells, so they can regulate how much they eat based on their needs. If you hide eggshell powder in the feed, they won't know how much they're eating, and too much isn't good for them in the long run. Commercial feeds that have calcium added have a formula of calcium to feed that's supposed to provide the right amount, but it's hard to guess if you're just eyeballing it. Especially because chickens' calcium needs vary greatly throughout the year and their lives. When they slow down or stop laying because of molt, winter, sickness, or age, their needs decrease, but if you have a mixed flock, and you pre-mix the calcium (or use layer feed that has added calcium), you're feeding everybody the same amount regardless of their needs, so some chickens will get too much while others may not be getting enough. Having the calcium in a separate container is best, so they can regulate themselves. They know best how much they need.
Broody hens eat the shells of the eggs after the chicks hatch, and those shells only break in two halves, so they resemble an egg a lot more than crushed shells do. And yet hatching chicks doesn’t turn hens into egg eaters. Eating their own shells is literally part of their nature, and nature has ensured that this act won’t sabotage their reproductive success by turning them into egg eaters. The hens that do start eating eggs are rare and are probably responding to the insides of the egg, like if one broke accidentally and they saw what was inside. I highly doubt it’s the shell that’s doing it - because they are meant to eat it after the chick hatches, to replenish their bodies’ reserves, without that becoming a problem.
Egg eaters suck, especially when they start teaching the others! But I bet she would've still done that even if you'd never fed her eggshells. Even people who feed oyster shell (or only use layer feed with no other calcium) report the occasional egg eater, so it can't be the egg shells... just bad luck...
