well... layers are for eggs, so they are kept and loved for this reason. (when they stop laying they are usually too old fer eating but go into a respected retirement nonetheless, what with time served an all that)
then unnecessary male chickens (coz you cant have too many, and this only stands if you hatch your own - you obv wouldnt buy males you dont want) you fatten up to 20weeks and then, yup, eat em!
win-win innit