April 2019 Base Change
April proof run in Italy is base change time. As a consequence, all the proofs go down because the reference point for the genetic evaluation has moved from the cows born 2010-2012 to cows born 2011-2013 and because the genetic level of the new reference group is higher than the previous one. There are no changes in GPFT on average because the GPFT formula gets adjusted for the expected variation in the proofs due to the genetic base change.
When changes are positive like for BCS this means that the genetic level of the cows in the base population April 2019 was lower for BCS compared to the genetic base group April 2018.
The average change for each trait evaluated is reported in the table below: