Mine love leftover meat. They've eaten bits of steak as well as picking the meat bits off pork chop bones, which we string to their cage to make it easier for them to pick at. For peace of mind we only give them scraps that are cooked through, nothing raw. If there are any pathogens in the meat, in theory they could be transferred from the raw flesh to the birds, so everything they get is fresh and cooked to the same doneness as we like.
Also, as we discovered shockingly this afternoon, the hens love mice. So if you have a mouse problem and lay traps (not poison!), you could probably feed the chickens the dead mice if they were "fresh" (again to avoid pathogens). Yuck, that makes me shudder, but my hen Rose was extremely happy when she caught that mouse....
