I am not a farmer so don't take what I say too seriously, but why not feed meat to hens?
I seriously disagree with feeding meat to sheep and cows which are herbivores, and not designed to eat meat, but hens and pigs are omnivorous like us. Hens even eat each other. Will meat really hurt them? Pigs are resistant to BSE and I would not be surprised to hear that hens rarely get it too.
I would no sooner feed a sheep on brains than expect a cat to thrive on potatoes, but I am not so sure on hens and meat.