Try just giving them fruit, table scraps, any source of calcium (if you have hens for eggs), and a source of protein ex. cooked meat that falls apart on a fork or meat that's easy to pull apart.
I have two roosters to mate with my 14 hens, one is a gray Orpington, the other one is a Barnevelder, and I have had them for 3 months now. My question is, how much older do they have to be to successfully mate?