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An update to Jersey Performance IndexTM (JPI) and Jersey Udder Index (JUI) will be implemented December 5, 2023, when the Council on Dairy Cattle Breeding (CDCB) releases the December official genetic evaluations.

The new weights of JPI2023 and JUI were approved by the Board of Directors of the American Jersey Cattle Association at a special meeting on September 28.

JPI2023 will have 55% of the emphasis on production (+6% from the previous version), 15% on fertility, 10% on survival traits (+2% from previous version), 10% on udder traits, and 10% on health traits. Traits included and their weights are PTA protein, 30%; PTA fat, 25%; Productive Life, 10%; Cow Conception Rate, 8%; Daughter Pregnancy Rate, 7%; Somatic Cell Score, -5%; Mastitis resistance, 5%; udder depth, 4%; fore udder, 4%; and rear udder height, 2%.

The inclusion of udder depth, fore udder and rear udder height traits to the JPI2023 formula are a direct result of the findings from the Risk of Culling study done by Dr. Kent Weigel and associates at the University of Wisconsin-Madison in 2022. With the new formula emphasis has been placed on increasing production and longer herd life while maintaining strongly attached udders. Some rescaling and re-ranking is to be expected in December as the focus on herd health with mastitis, components and udder depth has been increased.

Jersey Udder Index Updates

The AJCA board of directors also approved a new JUI formula at the September meeting. The formula is designed as a standalone publishable index. Weightings in JUI will change to 23% udder depth, 18% rear udder height, 17% fore udder; 15% rear udder width, 7% udder cleft and 5% each for teat placement, rear teat placement rear view, rear teat placement side view and teat length.

Additionally, emphasis was shifted in the JUI formula by making Udder Cleft, Udder Depth, Teat Placement, Rear Teat Placement Rear View, Rear Teat Placement Side View and Teat Length two-way traits with an intermediate optimum. Fore Udder, Rear Udder Height and Width will now be capped at maximum value.

Performance -Based Indexes for the Jersey Breed

“JPI2023 is a strategy to identify high-performing, healthy, and long-lived Jersey cows, while driving the breed to higher protein production,” Neal Smith, Executive Secretary said. “The new JUI index follows the same strategy as the performance-based JPI2023 index as it rewards high-performing, long-lived cows with durable udders. These two indexes are a positive step for the breed.”

The American Jersey Cattle Association, organized in 1868, compiles and maintains animal identification and performance data on Jersey cattle and provides services that support genetic improvement and greater profitability through increasing the value of and demand for Registered Jersey™ cattle and genetics.

For more information on the association’s complete line of services for dairy business owners, visit or connect at