What I feed from season to season sometimes varies... but so far for this season I've been feeding a mix of several feeds to my adults, for variety and also because I have a Turkey Hen in with one flock and 4 Peafowl with another AND because I eat a lot of their eggs, so I want them to have a varied diet... (I feed WAY out of the norm, and spend WAY more on feed than I have to, but it works for my flocks).
Here's what I mix together: 16% layer pellets, 24% game bird pellets, some rabbit food, some scratch grains, some sweet feed and either a few cups of cat fish diet, Ultra Kibble, or 4Health cat food (small amounts for extra protein)... and I usually refill their feeders every 5-6 days or so. All feeders are set to gravity feed at the slowest rate possible, so the birds can't pick thru the feed easily, but they typically leave a lot of the corn from the scratch as the feeders near needing to be refilled, which I empty out and give to my goats.
I mix up all the different ingredients in varied amounts depending on what I have, (but I try to use the layer pellets and game bird pellets as at least 50% of the entire mix) and I try to keep the total protein level of what I mix together at about 20% (adult Guineas really only need and can utilize 16% protein as adults tho). I also try to mix in more layer pellets in the laying season and more game bird pellets in the off season.
They also have free choice to oyster shell, grit, fine stem leafy alfalfa hay and they also get greens... plus free range time (1 flock is free range 24/7, 2 breeding flocks get kept in until most Hens have laid for the day then get let out to free range, and one flock is penned full time for the breeding season, for color control. They get wild bird seed mixes (mostly millet and BOSS) and extra sweet feed for treats each night at coop up time.
My full time free rangers only want a little sweet feed or some wild bird seed mix for a treat 2X a day, they don't care for commercial feeds, mixed or not. They eat alfalfa with the horses and goats, and have access to a feeder full of oyster shell, but typically get most of their diet off the land while free ranging.
My keets get medicated game bird starter up to 6 wks of age, then switched over gradually to a non-medicated grower feed that's 22% protein until they turn 12 wks of age (sometimes I'll use Flock Raiser, if I have to). They also get grit, wild bird seed mixes (that don't have BOSS in them), greens and grass/weeds after they are a several weeks old. After they turn 12 wks old then they are weened over to what I feed my adults, and also free ranged, unless they are birds that are for sale.