I don't even need a broomstick for cervical dislocation. Two fingers, one on each side of the neck right behind the head. Spin body in a circle until you feel the neck separate from the head. Then a quick jerk to complete the dislocation. Small birds will have the head pop right off.
A lot of people make their own feed and have no idea how poor quality feed it is. The corn and sunflower seeds are low protein high fat foods that need to be limited. Some add in flax seed which is another 50% fat food.
Of course if your object is to get them fat in a hurry for processing...