The relationship between yearling SC and age of daughters' puberty is way overplayed...
"The most often quoted data relating scrotal circumference of the bull and reproductive traits of his daughters indicates that for each centimeter larger a bull's scrotal circumference:
his daughters may reach puberty 0.8 days earlier
his daughters are more likely to calve for the first time 0.8 days earlier
his daughters' calf weaning weights are likely to be 0.75 lb. heavier
Hence, while the genetic relationship between scrotal circumference and age at puberty is "real", the impact of selecting for scrotal circumference on when a bull's daughters are bred and calve or on their potential lifetime productivity is small."
More good stuff on SC here:
http://www.kakahuangus.com/news/the-scr ... bandwagon/