The only birds that should be fed layer feed are the ones actually laying eggs, no one else (even roosters). I currenty have a mixed flock, consistin of four laying hens, 1 dormant hen, 1 rooster and five pullets, so I have them all on grower crumbles and I have can of oyster and powdered egg shells for them to pick at as they see fit. And the birds actually seem to know what it is and whether they need it or not, as only those that are actually laying bother to eat any, the rest ignore it completely.
I'm thinkng of starting up some sort of fermenter so I can augment their diet.