IMO fertility shouldn't be a problem, meaning it is a rare thing. An infertile tom can't produce young so he stops what ever his problem is right there.
It shows up in very inbred stock, of any kind is my understanding though usually other issues present themselves first when inbreeding is the cause. And fertility can be attributed to other things as well. If you have two boys and they constant y keep each other occupied, then who is breeding the lonely girls. TIme of year, feeding, lack of a specific micronutrient; many factors.
If you need to know if there is a fertility problem, keep him with the girls and then incubate test eggs.
It shows up in very inbred stock, of any kind is my understanding though usually other issues present themselves first when inbreeding is the cause. And fertility can be attributed to other things as well. If you have two boys and they constant y keep each other occupied, then who is breeding the lonely girls. TIme of year, feeding, lack of a specific micronutrient; many factors.
If you need to know if there is a fertility problem, keep him with the girls and then incubate test eggs.