I am sorry to tell you this but bread is one of the junkiest of junk foods for poultry. It has WAY to much fat and almost no nutrients/vitamins that are digest-able for the birds bodies to use. They get a load of fat and a full stomach telling them they don't need to eat much more that day but...
I found the best way to take my teenage chicks was to take them off the perch and hold them then put them back on when you are done. After less then a week doing that 6 out of 10 got to the point I can pet them and put of those 6, 2 of them I can pick right up with no warning and they don't ever...