What fertility do you get from Coturnix quail at that ratio. The paper that I remember seeing was that fertility dropped off if you exceeded two females per male in colony breeding. This study had a lot of birds in a pen. Do you mate two males and 20 females in separate pens?
I've started with a limited number of birds so my inbreeding is probably pretty high, but I only get around 50% hatch at a ratio of 2 females to each male for two lines that I maintain. They are color variants that aren't fixed and I usually cull pretty heavily on the males, but I try and maintain a 2:1 ratio.