AIPL Changes to Evaluation System - May 2003


New variances for type traits

By George Wiggans and Jan Wright

New estimates of variance components were introduced for evaluation of type traits for the Brown Swiss, Guernsey, and Milking Shorthorn breeds. The February 2003 data were reanalyzed using the new variances and the results for Brown Swiss and Guernsey were submitted to Interbull for the March test run. The new variance components were estimated using data since 1995 to force the estimates to reflect current data. Only small changes were seen in bull evaluations. The primary benefit is for traits such as udder depth where the variance has changed over time. An associated change was made in the method for adjusting for age and stage of lactation. New additive adjustments were computed and will now be used. New variances and age and stage adjustments are planned for the Jersey and Ayrshire breeds after the September Interbull test run. The Red and White breed will only have new evaluations calculated twice a year.


Parent averages provided for all traits

By Paul VanRaden and George Wiggans

Parent averages for net merit $, productive life, somatic cell score, and daughter pregnancy rate (DPR) were added to the cow evaluation format. All traits now have a parent average similar to the bull evaluation file, and these values are also displayed through the on-line queries. Bulls and cows without DPR data now have parent averages instead of zero in the DPR fields.