 There's something so wonderful about that story, your vegan neighbours taking care of the survivor chickens. Yeah, well, there you are. Charles has seen all kinds of systems, good and bad. His current set-up is a relatively small-scale indoor system. Two barns, about 20,000 birds in each. Now, 40,000 birds may sound like a huge amount, but the really big broiler farms in the UK can hold over a million birds at one time.