omnivorous--- the country boy approach. lol
Quail are able to eat a variety of foods (Vegetation's, Grains and Meats). They need higher proteins that are often not found in grains. In adults, I personally never had much luck getting them to eat a mix of grains (scratch) as they picked through the grain for their favorite (millet's) and left the rest and would only eat it as last resorts. Cracked corn and soybean were often left for days, ground soybean always being the latter and wasted. So the better food for the adults is that noted by most all of those who are aware of their needs (Higher Protein commercial feeds) 21-28% and the higher the better.
As young Chicks, I see grains useless and vegetation as more a summer supplement opposed to the more important foods they feed on and many unknowing feeders/owners seem to ignore. Meats.
Meats are insects, other and yes that can actually include the red and white meat products. Meats are much higher in proteins than a lot of the meal grains. In my arsenal meats play a larger role in the young chicks natural growth. In early hatches, i use Tuna and sardine's a supplement to any high protein chick starter. It takes the chicks a while to figure it out and that is fine, but they eventually eat all of it. In later summer, I supply them with their natural source of insects in the brooder and finisher.
The Omnivore status is obvious to most as the species I know of are labeled as being cannibals by nature, just like a chicken or other species of such natures. If you look at the quails, chickens, pheasants... beak it will confirm its omnivore status as it is curved at the end and though it is not as strong, it is roughly the style of a hawk beak, thus confirming its ability to tear away at flesh like meats. This is not to say go out and shoot some squirrels and throw them in the pen, but that is not a bad summer idea and depends on your squeamish natures, maybe even a health code issue for some.
In the hot summers, Dead animals and certain other foods will attract flies and other insects which lay eggs and make those gross little larvae we call maggots. Gross as it may be to us, most all birds enjoy the little white squirmers of human distaste as they also pack a punch of proteins. Thus I occasionally will let the insects have their way on a Pan of "Whatever" for a couple of days and when the maggots emerge, place the pan in the pen.
If you consider maggots beyond your stomach endevor but feed meal worms, then they too are from the same family of larvae so to speak. Meal worms are noting more than the Black Beatles larvae, laid in the ground and feeding on the compost of vegetation until and before they molt/mutate and reach adults.
Financially, all the above helps out as well as keeps the quail in their natural diets. But in spring/summer new comers should realize that a larger portion of the diet consist of the population and variety of insects (meats), as well as the editable vegies and grains they may encounter along the way. Winter time is the months when most quail will resort to the only available sources of foods "Grains" as the main food source as the others are more limited, thus the foraging of the grains sustains and keep them alive until the spring.
Personally, I have to agree with Quail in summer, I wouldn't pass up a rib-eye steak for a granola bar.