I have read that Australorps, big black ones from Australia, are good for heat. But I’ve never owned them.
I found a lot of Extension information, including stuff from Texas A&M, on the net.
That said, we have barred rocks, a dual-purpose breed, right now.
Indiana summers can have tropical humidity. In hot weather, we run a floor fan; put out extra water; pull the bedding back so they can rest on the concrete barn floor; but what works the best is to let them out so the birds can spread out.
In heat stress they will hold their wings out and pant. If 10 percent or more of your birds are doing that, you have a problem. If any of their combs and wattles turn blue or purple, they are about to croak. That’s a sign that their hearts are giving out.
Heat stress and panting will make their egg shells thinner because the extra carbon dioxides screws up their blood chemistry and calcium balance. You can offer more calcium (oyster shell) but a lot of times they are listless in the heat and don’t eat well, anyway.
Breeds that have larger combs and more exposed skin would be more heat tolerant. For instance, Australorps have big combs and Turkens or “naked necks” have more bare skin.
Hope that helped!
“Hope that helpede!”
It did! Thank you!