From what I understand, the roos without the black are showing the columbian gene which is restricting it. If your pullets have the black, then it may not matter which roo you keep... but I wouldn't want to get rid of the dark one.. just in case.
Males without columbian will have black mottled breasts, no colour or very little. Ideally one wants enough melanisers to give a black line between the white & the red. Columbian is necessary in order to be able to have the correct coloured breast. These birds which have red with white mottles but insufficient black line between the white mottle & the red colour are lacking melanisers.
Males without columbian will have black mottled breasts, no colour or very little. Ideally one wants enough melanisers to give a black line between the white & the red. Columbian is necessary in order to be able to have the correct coloured breast. These birds which have red with white mottles but insufficient black line between the white mottle & the red colour are lacking melanisers.