January 2010 Genetic Evaluation Changes

Several changes are being incorporated into the January 2010 genetic evaluations. Changes are being made to the TPI formula (Total Performance Index) to further assist dairymen with their breeding decisions and identification of superior cattle.

In both Canadian and American systems changes were applied to the genetic base. The genetic base updates are made annually to the LPI and every five years to the TPI formula. These changes are a sign of genetic progress and will not create any changes to bull or cow rankings. Instead the change will be seen in individual proof figures, with most traits decreasing.

Genetic Base Change: Genetic bases are updated every five years in the USA with previous updates occuring in 1965, 1974, 1984, 1989, 1995, 2000 and 2005. The next base change is scheduled for 2015. Major trait changes for each breed are listed below. For more detailed information on the genetic base change by breed please visit:

Additionally, the TPI formula was updated. Holstein USA has researched and analyzed traits that are important to dairymen in the USA and around the world. Dr Tom Lawlor, Holstein USA (HAUSA) Research Director has announced the genetic progress for both Production and Conformation has been very good in the past five years with additional improvements being made in Productive Life, Daughter Calving Ease and Daughter Stillbirth. Recognizing a need for greater improvement in health and fertility traits as well as the needs, strengths and opportunities available to HAUSA, modifications have been made to the TPI formula.

"The change leads to an increase in emphasis on productive life and daughter pregnancy rate; maintain the current emphasis on udders and feet & legs; slow the increase in body size; and reduce, by a small amount, the emphasis on production," says Lawlor. "These changes coincide with the views being expressed by commercial dairy farmers throughout the U.S. and abroad."

These differences are very slight, with the old TPI and new TPI formulas correlating at .97. Here is a quick look at the differences:

  • Production Emphasis: Decreases from 45% to 42%
  • Health & Fertility Emphasis: Increases from 27% to 33% (additional emphasis placed on Productive Life and Daughter Pregnancy Rate)
  • Conformation Emphasis: Decreases from 28% to 25%

For further details please visit:

Additionally, the Net Merit $ calculation was updated for all breeds, putting more emphasis on health traits like Productive Life, Somatic Cell Score and Daughter Pregnancy Rate, while decreasing production traits. Check out: for more information.

Genetic Base Change: Each year, Canadian Dairy Network updates the genetic base used to express genetic evaluations in Canada in conjunction with its first official release of the year. For more detailed information on the genetic base change by breed please visit: