I have 20 chickens 2 are roosters. So I thought I should be getting 18 eggs but I'm only getting 14-16 eggs a day. They are peeps from last year. Why am I not getting 18? I got 18 from tractor supply and 2 were hatched out they are mix breed. 4 hens and 2 roosters are Australorp. the others brown egg layers is what the sign said.