Older definitions are not always correct definitions. If you followed what you said, then you would be saying that a chicken and a peafowl are the same thing just because they can create offspring?
What? What are laughing emojis supposed to tell me?
The scientific name of a chicken is Gallus gallus domesticus, while the scientific name of red junglefowl-their wild ancestors-is Gallus gallus. So you said two different species there.
Just because chickens like something does not mean it is good for them. Chickens also eat plastic and other random things, but that does not mean they should be eating it.
When fed in large/medium amounts of too often, it will bloat chickens and all other birds. Eating too much bread can cause death by bloating, or obesity. Bread has no real benefits for chickens, it is more of a filler than anything, which is why it bloats. Because it is not beneficial for them...
Anything with too much salt. Chickens get poisoned from salt easily if fed too much of it, since salt is not regularly found in what they normally eat.
Foxglove. All parts of a foxglove should not be fed too chickens, as it is toxic.
Nightshade. Nightshades can be very toxic to chickens and...
Cat food is definitely not bad for chickens. I feed my chickens cat food alongside chicken feed because their normal feed does not have enough protein, plus they love it anyways. I think bread should be added to the list. While bread is not toxic, it can easily bloat chickens when fed in large...