Stumbled on a study about chicken feed and egg shell thickness

I was digging around online after my hens started laying thin shells. Found a fact from a poultry science journal that said calcium carbonate particle size actually matters more than total calcium amount. Bigger particles stay in the digestive tract longer for overnight shell formation. I switched to a mix with larger oyster shell pieces instead of fine powder and within 2 weeks the shells got noticeably harder. Cost me an extra $4 per bag but worth it. Has anyone else played around with different calcium sources and seen a difference?

3 comments

3 Comments

james_ramirez2mo ago

Hang on, you sure it was a poultry science journal that said bigger particles are always better? From what I've read, the size matters for sure, but it's more about the combination. If the particles are too big, they just pass through without breaking down enough for the hen to use overnight. You want a mix of sizes so some breaks down fast and some stays around longer. But hey, if the switch fixed your shells, that's what counts.

jason5242mo ago

My neighbor Bob tried the exact opposite approach last year. He ground his oyster shells down to almost dust because he figured the hens would absorb it faster. His eggs got so fragile you could crack them just looking at them wrong. I told him he was basically feeding them calcium sidewalk chalk. He switched back to the big chunks after one of his hens laid an egg that cracked before it even hit the nesting box. Sometimes you just gotta let the birds do the work themselves I guess.

verap5228d agoOG Member

james said it best about the mix of sizes. I think the real trick is finding that sweet spot where the bigger chunks hold in the gizzard overnight for the shell building, but not so big they just get passed whole. The hen's crop and gizzard do the grinding, so the dust approach jason's neighbor tried just skips that natural breakdown and gives them nothing to hold onto. My vet explained once that the calcium needs to be available in the bloodstream at night when the shell is forming, and the finer stuff gets flushed out too fast. So yeah, blending some larger oyster shell with a bit of the smaller stuff gave me the best results overall.