If you watch Super Size Me 2, they go into a lot more detail on why the selective breeding is so disturbing.
Amoung other things, the birds are bred for meat muscle development, their cardiovascular systems have not been equally enhanced and as a result, chicken farmers know that the birds are big enough for slaughter because some of them will just start dropping dead of heart failure.
If you watch Super Size Me 2, they go into a lot more detail on why the selective breeding is so disturbing.
Amoung other things, the birds are bred for meat muscle development, their cardiovascular systems have not been equally enhanced and as a result, chicken farmers know that the birds are big enough for slaughter because some of them will just start dropping dead of heart failure.