Jumbo eggs

[Tebogo]

Breeding a hybrid like ISA Browns or other layer mix is going to yield very inconsistent results.

Better to look at the anatomy of chickens that lay larger eggs and breed for the physical form.

Leghorns lay very big eggs relative to their body size. Such that I feel any large-laying project should include them (and I did in mine).
What physical attributes let them lay so large?
The part I know of is that their bones are thinner. That is carried through the whole skeleton so the pelvic aperture has less bone material, making more room for an egg to pass. Those thin bones make for thinner shanks as well, which are visible for the breeder to see. The roosters leg width matters for his daughters as well.
I'm selecting for skinny legs in my project. Also for bigger birds.

There are probably more secrets to big eggs out there, but I haven't learned of them yet... if anyone does, please share!

Thanks you for the insightful reply