My main problem with bread is what it does not have (total protein content, certain amino acids in particular, many vitamins and minerals). A chicken will only eat so much food in a day, so eating more bread means they eat less other stuff. Depending on how much of what other stuff they are eating, they may not get enough of the things bread lacks.There's a lot of hostility on BYC to giving bread, but I see no problem with it as yet (of course time may prove me wrong), and I've not to date read anything to explain what exactly is supposed to be the problem with it. Anyone who thinks they know, please chip in, but I'm not interested in unsubstantiated condemnations; I want to see some evidence please.
Also, bread comes in many different forms. I have no problems with chickens eating small amounts of any kind of bread, but I would not want them to eat large amounts of most breads that can be bought in the stores in my country (USA).
My main problems with the common breads:
--sugar content
--salt content
--the main ingredient is refined flour made from wheat (wheat does not contain everything a chicken needs, and refining it removes even more of the nutrients. Most of them are not added back into the bread.)
My views on feeding bread to people are about the same as feeding it to chickens. It depends on the bread, the quantity, and what else is being eaten with it.