I don't have those answers, but it's been widely reported that the carbon footprint of a calorie of chicken is about one quarter the footprint of a calorie of beef.
Just switching animal proteins is a big change. And chickens are omnivores. Feeding them invertebrates instead of feed corn would be a more natural diet for them, and you can use food no longer fit for humans as the feedstock for those invertebrates without switching humans to cricket flour.
I know of a guy who uses cows, pigs, and chickens to control pathogen load on his farm. The lifecycle of flies on cow manure are very predictable, and with some discipline you can use it as feedstock for the chickens. We know how to do this outside, I doubt they know how to do it in a feed lot (although, making it work in a feedlot would necessarily result in better sanitation for the cows/pigs, since you'd have to isolate their waste chronologically).
Part of pathogen control is sending your inputs through as many diverse digestive tracts as you can. Or using a ton of chemicals. Mammal->insect->chicken->human is pretty good for eliminating parasites, though maybe not salmonella.
[ETA]
Most of what I said about chicken feed is also true of pigs, although their footprint is somewhere between the two extremes.
Just switching animal proteins is a big change. And chickens are omnivores. Feeding them invertebrates instead of feed corn would be a more natural diet for them, and you can use food no longer fit for humans as the feedstock for those invertebrates without switching humans to cricket flour.
I know of a guy who uses cows, pigs, and chickens to control pathogen load on his farm. The lifecycle of flies on cow manure are very predictable, and with some discipline you can use it as feedstock for the chickens. We know how to do this outside, I doubt they know how to do it in a feed lot (although, making it work in a feedlot would necessarily result in better sanitation for the cows/pigs, since you'd have to isolate their waste chronologically).
Part of pathogen control is sending your inputs through as many diverse digestive tracts as you can. Or using a ton of chemicals. Mammal->insect->chicken->human is pretty good for eliminating parasites, though maybe not salmonella.
[ETA] Most of what I said about chicken feed is also true of pigs, although their footprint is somewhere between the two extremes.