Kevin McDermott Sheep IReland explains some of the difference found in the CPT between 2013 and 2015 when comparing 1 Star vs 5 Star at an individual trait level over 7,500 animals.  In this case the 5 Star, 5 Star mating combination, resulted in an extra 17% lamb at the point of weaning compared to the 1 Star, 1 Star mating combination. The differences are stark and prove that extra profit can be made if continually selecting 4 or 5 star animals for breeding. Granted the difference here are using the extremes, if even a fraction of this increase could be applied across the national flock it would have a major impact on the industry.