few different ages. It could be 2 of my males are getting too old they are around 4 years old. Didn’t quite realise how old they where!It could be that there isn't enough protien then. How old are they? What lines? I have a male that the entire line I hatched was infertile, so no more baby quail for Jacin
I have had fertility eggs from them before, I hatched a few last year
But always keep your eyes open for the highest protein possible. You could always supplement them with a small bit of cooked plain ground beef or turkey meat. 1/2 teaspoon per day per bird. This would probably get them up into the proper protein range. Good for feather growth and sheen too.