i myself have concluded they are genetically faulty/a failure, man has bred them too much and they have so many weaknesses and things like heart and liver problems..... most of out comercials have died from mysterious things, the most experienced of the forum are even confused about....
i mean like the standard chook you buy from a farm store, the ones that grow REALY fast, and lay nearly a egg every day, not pure breeds but the standard commercial breed.... they come in red/brown black and white.....