The above listed site suggests that they weigh in at around 50% protein. They're quite easy to raise.
Redworms are easy to grow indoors on vegetable kitchen waste as well. I assume they have an equally high protein content. Worm farm instructions are available many places on line, as are starter packages of redworms. Basically you put moist newspaper and some vegetable trimmings in a plastic box, throw in some worms, and you get out more worms, and the finest fertilizer you can find. They reduce the vegetable matter to what looks and smells like good, black, dirt. I assume it is all worm poop though.
Anyway, there's two easy to raise "bugs" that you could feed to quail. They both can eat what is more or less waste, and provide a boatload of protein.