I used to have fertile eggs. I have full size and bantam hens and I had 3 bantam roosters and 1 full size rooster. 2 of the bantams were fighting too much so I gave them away. I kept the sweetest bantam rooster and the head rooster, a Jersey Giant. But ever since those little troublesome bantams left I have only inferile eggs. My two roosters are responsbile roosters who take good care of the 7 hens and they are... very sexually active... but the bantam and full size hens are laying infertile eggs. I don't suppose there is anything I can do about that is there? I got all my chickens as chicks in late summer last year so I know they are old enough.