JPITM Update At Right Time To Move Breed Forward
With the release of the official CDCB-AJCA genetic evaluations on April 4, updates to Jersey Performance IndexTM authorized by the AJCA Board of Directors at its March meeting will be implemented. Three new traits were added—CFP Milk, Body Weight Composite, and Livability—and weights were adjusted for previously included traits. Because of that, plus new economic weights and standard deviations, there’s a new range in JPIs and, yes, there was re-ranking.
The traits and weights in JPI2017 are PTA protein, 30%; PTA fat, 15%; CFP Milk, 8%; Functional Trait Index (incorporating Jersey Udder IndexTM, Body Weight Composite, and mobility), 20%; Productive Life, 6%; Livability, 4%; Somatic Cell Score, 6%; Daughter Pregnancy Rate, 7%; and Cow Conception Rate and Heifer Conception Rate, 2% each.
Overall, 53% of the emphasis is on production (-5% from the previous version), 27% on fitness (no change), and 20% on functional type (+5%).
We expect you’re asking, “Why change JPITM now, instead of waiting for the scheduled update in 2020?”
The answer is simple. Because opportunity presented itself, and to postpone action would have been to delay breed progress.
The revisions made are as bold and forward-looking as any ever made to JPITM. They draw on new research as well as the key findings from the 2012 Capper & Cady study, that Jersey sustainability requires increasing milk yield, maintaining—or better yet improving—component levels, and maintaining characteristic body size.
The innovations are two new components that each, in their own way, are tailored to Jersey breed progress.
The first is CFP milk (8% of the index) because of its objective: for every pound of PTA milk, there needs to be 0.088 pounds of combined fat and protein. Few will argue with the premise that it is preferable to have the same amount of fat and protein come in more concentrated milk than in a larger volume of watery milk. To illustrate the effect of CFP milk on JPI, consider two bulls that have the same combined pounds of PTA fat and PTA protein (160 lbs.), but a large difference in their PTAs for milk (1,600 lbs. vs. 2,500 lbs.). Relative to the target of 0.088 pounds CFP to one pound PTA milk, the bull with a PTA of 1,600M exceeds that concentration and will gain JPI points. The other bull, at PTA 2,500M, transmits more water relative to components and therefore will lose JPI points.
The other innovation is Body Weight Composite (7% of the index). It is a proxy for feed efficiency. BWC was developed from actual weights and linear type data from Holstein research herds that also have measured feed intake. CDCB uses those relationships to predict body weight of all dairy cows. Because of that, BWC is far from a perfect measure for Jerseys, leading the Board of Directors to approve an aggressive program starting right now to get Jersey data. Until there’s a Jersey BWC, however, the penalty of 7% on body size included in JPI2017 is larger than what is applied in the CDCB Net Merit index. It will select in the direction of moderate-sized, efficient cows.
Jersey Performance Index2017 is a formula for increasing production and improving milkfat and protein levels in the milk, moderating body weight in service of greater productive efficiency, and at the same time selecting for longer herd life, greater fertility, and better udder health.
It’s a formula for moving the breed forward.
Neal Smith, Executive Secretary & Chief Executive Officer