Setting aside arthropods for a moment, I worry about the idea that switching to slower-growing breeds of broilers could lead to an increase in the total number of broiler-years endured in factory farm conditions (just because they might live for 70 days each rather than 40).
You’re then right to then raise an additional concern about land use change and its impact on insects in the scenario where meat production is held fixed but slower-growing breeds are used.
I tend to think of it like this: broiler and cage-free campaigns are not really aiming to change methods of production while holding fixed the amounts produced. They’re aiming for a reduction in the size of the industry, at least compared with what it would have been otherwise, due to growing consumer concern about the way the cheapest products on the market are produced.
This way of thinking about it reduces your particular concern while raising others. It now assumes lives in factory farm conditions are not worth living overall, and it assumes these campaigns are cost-effective ways of counterfactually reducing meat consumption. I hope they are, at least in some countries, but it’s hard to tell.
It’s great work, very thoughtful and well designed. Thanks for this summary.