Are thicker shell eggs healthier for people and chickens?

[NatJ]

Is it necessary to supplement their diet with some kind of calcium supplement?

The packaging says it's 16% mini-pellet layer feed.

They will probably be OK without a calcium supplement, because "layer feed" usually has enough calcium. But leaving some oyster shell or eggshell available is also fine, and might help if some individual hen needs a little extra.

My girls refuse to eat the crushed oyster shell that I bought for them, so I've been concerned about the amount of calcium they get. I've considered crushing their own shells, baking it, and giving it to them.

You don't need to bake their eggshells--just squish it a little, so it's in pieces instead of looking like half an egg, and toss it to them. They will either eat it or ignore it, according to how much calcium they do or don't need. If they are ignoring the oyster shell, they are probably doing OK on calcium.

 

[Red-Stars-in-RI]

I look at oyster shell or other calcium supplements as cheap insurance. A 50 lb bag could last you years for a small backyard flock. I paid $18 for the last bag I bought that size.

 

[CanadaEh]

My girls refuse to eat the crushed oyster shell that I bought for them, so I've been concerned about the amount of calcium they get. I've considered crushing their own shells, baking it, and giving it to them. Is it necessary to supplement their diet with some kind of calcium supplement

If they egg shell not thin, may be they don't need calcium supplement especially if you are feeding layer feed (which already contains it). When switching from saved egg shells to purchased oyster shells we had to wait for a week or so before they started to eat them.

 

[CanadaEh]

I offered my Barred Rocks at 17 weeks old Oyster Shells in a separate container.
7 pullets consumed nearly a quart in 3 days. None keeled over. It's not like poison. It takes awhile to OD on calcium.

I meant long term health effects of "just right amount calcium" vs. "too much calcium causing super thick egg shells with calcium deposits"

 

[NatJ]

I meant long term health effects of "just right amount calcium" vs. "too much calcium causing super thick egg shells with calcium deposits"

I think chickens usually adjust their calcium consumption to safe levels, when they have the option to do so. So I wouldn't worry about it.