What is JUI™?

JUI^™ - what is it and how should it be used?

Jersey Udder Index^™ (JUI) was established as a reference tool for Jersey breeders to use when selecting sires. Formulated by the American Jersey Cattle Association, JUI is based on lifetime profitability. The respective weights of each trait in the formula are based on the traits relation to lifetime profitability.

Calculation of the Jersey Udder Index

This index is the sum of a sire’s Predicted Transmitting Abilities (PTA) for udder traits multiplied by their weights in the Functional Trait Index: Jersey Udder Index (JUI10) = [(.30 x FU) + (.35 x RUH) + (.61 x RUW) + (1.0 x UD) + (.85 x UC) + (.10 x TP) + (0 x TL)]

When you split out the weights of JUI, the highest priority trait is udder depth. Nearly one third of the index is based on this trait. Following udder depth in importance is udder cleft. Udder depth and udder cleft together make up well over half of the JUI index. The third and fourth priority traits are rear udder height and rear udder width respectively. Rounding out the final traits for the JUI index include fore udder and teat placement.

The thing to keep in mind when referencing the JUI index is that JUI needs to be balanced with production traits. Because there are such high weights on udder depth and udder cleft, often times functionally correct and highly profitable sires will not see the extremes in their JUI rankings. As a reference point, based on the August 2013 sire summary, ranges for JUI on all active sires is -3.00 to +7.53.

The top Genex JUI sire is 1JE00812 HAWTHORNE (Zuma x 90 pt. Paramount). HAWTHORNE comes in with a +5.12 JUI and complements this with huge Cheese Merit Dollars (CM$) of +584. In the number two spot, 1JE00806 TORONTO fits in with a +5.06 JUI. TORONTO hails from one of the most popular cow families of the breed with TORONTO’s dam being Heartland Nathan Texas-ET, EX-95%. When highlighting JUI, 1JE00654 ALLSTAR has to be mentioned. With over 300 daughters scored in his type proof, ALLSTAR keeps climbing on his JUI ranking and comes in at +4.51 with 96% reliability.

When looking at the Genex active sire listing, post August 2013 proofs, we boast an impressive JUI across all active sires of +2.85. Our GenChoice™ active lineup comes in just a hair under +3.00 JUI (+2.97) and carries an industry leading total number of available sires as well as elite pedigree diversity. As with any index, JUI should be used as one tool in the bigger picture of fitting your genetic needs.

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Author Leah James is our U.S. Jersey Marketing Manager.  James grew up on a family dairy farm and graduated from the University of Wisconsin-River Falls with a bachelor’s degree in agriculture education. She has since worked within the artificial insemination industry and for the American Jersey Cattle Association. Today, she and her husband also operate a 125-cow dairy consisting of registered Holsteins, Jerseys and Milking Shorthorns.