I have 14 pullets 22 weeks old. 8 RIR and 6 BR. When they were young and the rooster first started doing his mating thing he would just grab a pullet RIR or BR it did not seem to matter. Well the RIR girls are laying and the BR have not started. Now when I see him mate a hen it is always a RIR. Is it because they are more mature because they are laying?