 The fact that the birds are very big, they grow very fast, isn't guaranteed to cause health problems, but it does seem to be associated with some health issues. The one that's gained the most attention really would be problems with walking that some birds have. Another is when birds are left to sit around in their own muck. And that can cause skin problems for the birds. And although chickens in some systems have enrichment, things like hay bales to perch on and hanging things to play with, that's not the case for all indoor birds.