When I have had a cockerel running with my girls I noticed that the two ex-barns are the ones who lose the most condition from mating and even now, a couple of months after the last cockerel went, one of the girls has not refeathered as well as the others as a result. You will need to keep a close eye that he doesn't favour just one of them as although a strong purebreed would be able to cope with this an ex-bat may find it too stressful and will suffer more. Although a saddle would solve this problem in terms of feather loss if they still have weak bones there could be more serious damage.
I love having a cockerel in with the girls and don't by any means think I am trying to put you off as I think if they are strong enough to go ahead and try as they will actually prefer having him around
![happy :)](https://chat.allotment-garden.org/Smileys/green/smile.gif)
We have forgot to tell you we need pics of all your little feathered ones - 'tis the law on here
![biggrin :D](https://chat.allotment-garden.org/Smileys/green/biggrin.gif)