If you want them to lay well, especially if you have hybrids, it's advisable to feed layers pellets, which will have been designed to provide a balanced feed to cover their whole nutritional needs, including vitamins, minerals, and the extra calcium they will need to continue laying eggs with good shells. Have this available all the time, never let the feeder get empty, so they look on it as their main food source. Then you can add very small amounts of extras, such as not more than an eggcupful of mixed corn per hen per day, at teatime is a good idea, to help keep them warm overnight. Not too much as its fattening. They do need access to suitably sized chicken grit, the right type of flint in order to grind up food in their gizzards, and although yours may get this whilst out in the garden, it's still a good idea to provide a hopper of mixed grit and oystershell in the run in case they can't find enough of the right size and type in your garden. The oystershell may help to supplement their diet with extra calcium at times of stress, and they will just nibble when they feel the need. They won't eat large amounts of this mixture but it's cheap to buy and it's good practice to offer it for them to choose if they want it. Best to let them eat pellets first thing, a bit like bread and butter before pudding, so they get enough of the good stuff before filling up on greenery. A simple diet is really all they need, if they get fat on unsuitable extras it will affect their capacity to lay properly and may even lead to prolapse or peritonitis in some cases.
