August 2017 Genetic Evaluations

摘要

At the summer 2017 meeting of the Holstein Association USA board of directors, several changes were approved to the Total Performance Index (TPI) formula, as well as some of the type composites.UDDER COMPOSITES (UDC) UPDATES: The individual weightings of traits have been updated, and two new traits have been added - Teat Length and Stature. The addition of a negative weighting on Stature is in response to concerns from the industry that the Holstein type composites have too strong of a relationship with Stature, and by selecting for high UDC and/or high FLC, one was inadvertently also selecting for taller cattle. By decoupling UDC from Stature, the index is now more accurate. Additionally, anintermediate optimum is being used for both Rear Teat Placement and Teat Length. Bulls siring cows with rear teats too close together will be penalized, as will teats that are too short or too long.