A change for TPI

摘要

The Total Performance Index will now include more information on feet and legs. Holstein producer Chuck Worden always knew the rear legs of his cows affected longevity at his 800-cow dairy in Lovington, N.M. "When you milk in a parallel parlor, you really see how the rear legs affect mobility," he says. However, until January 1996, the Holstein Association did not publish data on the rear view of rear legs for the cows it classified, so producers like Worden could not select on that trait. Now, in addition to publishing the rear leg/rear view score, the Association will use that trait in its most popular index — the Total Performance Index (TPI). And, the weighting it gives to feet and legs will increase from 7.5 percent of the index's type data to 25 percent. Those changes should help Holstein breeders select on longevity. While most geneticists would not look initially to the TPI index for longevity, they agree the change has improved the correlation between the index and longevity traits. Prior to 1996, the Holstein Association evaluated feet and legs on the following two linear traits: side view of rear legs and foot angle. Now, rear legs/rear view has been added to the overall Feet and Legs Composite score (FLC). The FLC is an overall score assigned by the classifier in addition to linear traits — similar to how Udder Composite is scored.