Leghorns dont lay eggs as offten as other chicken species black australorps too dont lay as much eggs. If they are old 20 weeks and not laying at all then somthing is wrong...
What!?!
Both breeds are Super Egg Laying Machines! Both can put out 6-7 eggs/week. If yours aren't putting out at least 5 or 6 a week, they're either sick, stressed, or starving.