as stated, you can feed whatever you like. they are your little buddies. I am feeding GBS (Game Bird Starter)
to maintain optimum condition and growth rate in quail from hatch to whenever- I have gathered by reading, I am a faster reader, 28-30% Game Bird Starter is recommended by 95% of the avatars on this forum.
you want your quail to gain as much nutrients per mouthful as they can. the big companies spend lots of time and research figuring out how to get the most bang for their buck and pass on the result to you (retail).
if "I" wanted to supplement the birds diet of GBS, I would feed:
>90% of their diet as GBS.
<10% anything else in moderation, what would that be.
anything "I" like, put it in a separate container for them to pick at, watch them, if they start eating too much cut it down. I am not sure what is poisonous to quail, (some think catfood and can make a good argument). that is a good topic for a post, people do ask repeatedly.
what would "I" try to add to their diet?
spinach? I want quail that look like they have little popeye wings.
alfalfa? I want them to be big as draft horses. in case the tractor breaks down and they need to pull it.
apples? I like apples. like the matt damon line in Good Will Hunting, "how do you like those apples?"
If "I" wanted to bust out a blender, which I may, with garage door open and fan on.
oatmeal?
ground soymeal? higher protein, as someone already suggested.
ground oyster shell, as already recommended.
egg shells?
"I" would feed this separately, to control my 9:1 ratio.
"I" may even blend the GBS to a little finer, to aid in digestion. read that someone very knowledgeable does that.
"I" would consider a handful of mealworms, millet seed, cracked corn or scratch as a "treat" for them, as already suggested. I read a few posts back they come running for it. again "I"intend to keep this % low compared to their staple diet of GBS.
also good advice a few posts back on what to get if you can't get GBS (Game Bird Starter).
in my humble opinion, if "I" intend to eat their eggs or them, consider this- would I eat what I was thinking of feeding them.
also, I would not give them any of the coffee that made me type this.