Changes to Evaluation System - May 2004


New variances for Jersey and and Brown Swiss type

By George Wiggans and Jan Wright

New variance components for evaluation of Jersey and Brown Swiss type traits were introduced. The new estimates for Brown Swiss were necessary to allow use of the same model that is used for the other non-Holstein breeds. Changes for Jersey variance components should more accurately reflect the current data by being based only on appraisals since 1995. They also should better estimate the relationships between the 14 linear traits without body depth, which is no longer scored. Current genetic parameters are found in the Type Evaluation Description document. Changes in heritabilities (new - old) for these breeds are:

Trait Brown Swiss Jersey
Final score -0.127 -0.035
Stature 0.120 -0.025
Strength 0.009 -0.036
Dairy form -0.001 -0.022
Foot angle -0.016 0.001
Rear legs (side view) -0.022 -0.034
Body depth 0.019 ···
Rump angle -0.020 -0.096
Rump width 0.001 -0.021
Fore udder attachment -0.004 -0.035
Rear udder height -0.012 -0.006
Rear udder width -0.007 -0.005
Udder depth 0.035 -0.110
Udder cleft 0.000 -0.030
Front teat placement 0.004 -0.046
Teat length -0.012 -0.072

Jersey Interbull type evaluations

By George Wiggans

Changes to U.S. evaluation methodology for Jersey type traits were accepted by Interbull based on March test run results. However, because of rather large changes in variance for some traits, the May U.S. Jersey type evaluations were not accepted for inclusion in Interbull evaluations. Instead, the U.S. evaluations submitted for the test run (appraisals included for February U.S. evaluations but with variance component changes described above applied to calculations) were used for May Interbull evaluations. Officiality of evaluations (Interbull vs. U.S.) was determined as outlined in "AIPL Changes to Evaluation System - May 2001."