Quail kept in cages won,t get any protein from bugs, perhaps a mosquito or two on occasion and that providing they are kept outdoors.
I do not claim to be expert on nutrition, the fact is as I stated before that my quail feed exclusively Purina Game bird developed Vit B deficiency.
This deficiency dissapeared very soon after I switched to other brand, I believe it was Nutrena at the time.
And I know for sure no plant contains Vit B12, it is foud only in animals products.
Speaking about junk put in commercial feed in general, that,s a fact, just like junk put in processed human food.
All hoopla and propaganda shoveled down our troats by feed industry and most vets that anything else but commercial stuff fed to animals is harmful, is obviously protecting their interest.
I feed my chicks all kitchen scraps exept greasy. spicy and salty stuff, also all kind of grains including whole oats, and some wild bird mix as a supplement beside crumble or pellets. They love it and thrive on it.
I will experiment with quail also as far as alternative foods are concerned.
Somehow all domestic animals and birds survived and thrived for millenia without commercial feed which was developed not long before WW2 I believe.
How about all magnificent chicken breeds like RIR,s Rocks, Wayandottes etc.?
Theese were developed long before commercial feed was invented.