Editor’s note: This article appeared in the most recent CDCB Connection and walks through the 2020 Genetic Base Change for all breeds.
The Council on Dairy Cattle Breeding has just released the following document outlining the changes that will take effect with the April 7, 2020, triannual evaluations.
The genetic bases to which (most) dairy traits are expressed in the United States have been updated every five years since 1980.
For the last base change in 2015, the average predicted transmitting abilities (PTA) of cows born in 2010 were set to zero. Milking cows born in 2015 define the new base, and their PTAs will be set back to zero with the April evaluations.
Because gains were made across five years for most traits, most PTAs will be lowered by the amount shown in Table 1 in the complete article.