I heard that internal laying is very common in those breeds bred mainly for laying eggs, so what about dual purpose hens? Also, what's the main cause for this? I've also heard that there's no cure for it other than performing surgery on the hen and removing her ovaries. Is it just best to put the bird down when you find out it's laying internally?
I think this thread, and particularly this post, will be of interest to you: https://www.backyardchickens.com/t/79443/tell-me-about-your-internal-layers/90#post_6235380
