Breed purity is a hot topic for Jerseys.

Many of the elite sires have been upgraded from Holstein heritage through the Jersey Genetic Recovery and Jersey Expansion programs. These programs allow breeders to enroll animals with a Jersey appearance, or those sired by a Jersey bull, into the herd registry. While they have proven beneficial in growing the registered Jersey population, some unforeseen impacts have left many producers confused as to just what qualifies an AI bull as a Jersey.

The American Jersey Cattle Association (AJCA) board of directors has worked with animal ancestry via pedigree and genomic data to come up with some visual cues to eliminate confusion on Jersey purity.

Generation Count and a JX prefix have been added to full names to signify a hole in the pedigree or unknown dairy ancestry. Breed Base Representation (BBR) is now displayed on all animals recorded with the ACJA to represent the amount of Jersey blood within the pedigree.

Generation Count (GC)

Generation Count demonstrates the depth of Jersey ancestry. An animal’s name will include a suffix enclosed in braces { } to indicate the number of generations of AJCA-recorded ancestry from 1-6. A GC of 1 means the animal is one generation removed from an unknown or non-Jersey in the pedigree. A GC of 6 means the animal is six generations removed from an unknown or non-Jersey animal.

The GC is dropped when seven or more generations of ancestors are recorded by the AJCA. The offspring of a mating with be one generation count higher than the lowest parent.

JX Prefix

A JX prefix is now found on the majority of the pedigrees that contain a generation count. The JX prefix indicates that there is unknown dairy (most commonly Holstein) parentage in the pedigree. The GC will then indicate how far back in the pedigree the unknown dairy breed can be found.

If you find a bull with a GC but no JX prefix, that means that the missing part of the pedigree is an unidentified Jersey. 

Breed Base Representation (BBR)

BBR is a genomic-measured trait that compares the DNA of a genotyped animal to a Jersey reference group and all other breeds. The Council on Dairy Cattle Breeding (CDCB) policy is to report BBR values of 94 or greater as 100 due to standard deviations. Bulls below 94 will have an expressed value. The AJCA will publish a BBR value for all recorded animals.

Males will be published on one of two reports.

Males on the main list include those who:

  • are Herd Registered
    • more than 6 generations of identified Jersey parentage
  • have a Generation Count of 4-6 and a BBR of 100

Males on the secondary list include those with a:

  • Generation Count of 3 (regardless of BBR)
  • Generation Count of 4-6, if their BBR is less than 94


Here are a few examples to show this Jersey breed purity lingo in action.

JX Ahlem Jumbo Kaa { 5 } – ET   BBR 100

  • KAA is 5 generations from an unknown dairy breed and is BBR 100
  • Offspring will be Generation Count 6 and 100 BBR IF he is mated to a GC 5, 6 or HR female

JX Oomsdale Brazo Gratitude Ghent { 2 } – ET   BBR 82

  • GHENT is 2 generation from Holstein influence and is BBR 82
  • Offspring will be Generation Count 3 and Non-HR.


At Alta, we are committed to supplying our clients around the globe with the most reliable genetics available. In order to fulfill this promise, we offer a diversified Jersey product lineup focusing on the traits that are most profitable to our clients’ dairies.

We have the highest level of confidence in the genetic and genomic predictions of BBR 100 bulls and the performance those daughters realize in the milking herd. We recognize that clients have choices, so we will always market with full transparency.

To learn more about the Rules for the Registration and Transfer of Jersey Cattle, click HERE.