Ranking the top sires of AI sons and the top herds contributing sons to the AI industry was begun by Larry Specht in the mid-1970s, explains Chad Dechow, associate professor of dairy cattle genetics at Penn State University. Known as the Specht Report, the tool’s value continues today to help you identify elite cows, bulls and breeders.
You can use the three reports (Sire-Son, Prefix, Bull-Mother) contained within the Specht Report to rank bulls for a variety of traits.
In addition, you can see how many sons have entered AI during the past 25 years, the age of those sons, the Lifetime Net Merit $ (LNM$) of the bull and his sons, average son predicted transmitting ability (PTA) for yield (milk, fat, and protein), average son PTA for type, and average son PTA for health traits (productive life, daughter pregnancy rate, and somatic cell score). Only sires and herds with at least 20 sons in AI during the past 25 years are considered. Cows are required to have 10 sons to be listed.
Source: Dairy Digest