Sire Summary Update

April 2020 Sire Summary Updates and Adjustments

PLAIN CITY, Ohio, April 6, 2020 — The April sire summary is coupled with substantial genetic updates including relevant changes to index formulas and evaluations and the introduction of additional wellness traits.

Genetic base change

A scheduled base change will adjust Predicted Transmitting Abilities (PTAs) of all animals to account for the genetic change that has been made over the past five years. Resetting the genetic base prevents PTAs from becoming extreme by setting the average PTAs of animals born in 2015 at zero. Because genetic progress is typically made over time, most PTAs will be lowered. However, if the trends were unfavorable, the PTAs will generally increase. Exceptions to this trend being Somatic Cell Score (SCS) and the four calving traits as lower values are more desirable in these traits. The full chart of estimated changes for all linear traits can be seen at             

Key Progress Points

  • All lifetime merit indexes showed genetic improvement for all breeds.
  • Genetic gains were made in all three yield traits (Milk, Fat, Protein) for all breeds.
  • Changes for Somatic Cell Score (SCS) in April will be small for all breeds except Holsteins which will increase by 0.08 due to their progress in lowering somatic cell counts.
  • Guernseys, Holsteins, Jerseys and Milking Shorthorns all increased their genetic capacity for longer life.
  • The Holstein breed improved for all three fertility estimates.
  • Mastitis resistance was among five wellness traits that showed improvement in the Holstein breed.
  • The rate of genetic improvement in Holsteins and Jerseys was more than 1.5 times faster between 2010 and 2015 than it was in the previous five years.

Holstein Association USA adjusts TPI® formula

The Holstein Association USA, Inc. Genetic Advancement Committee reviewed genetic progress of the breed and analyzed the current and forecasted changes in milk pricing and identified improvements for TPI.

Key Points

  • PTA Fat and PTA Protein will now receive equal weighting of 19 percent.
  • Using the most recent economic assumptions for Cheese Merit Dollars (CM$), based on USDA research, the Feed Efficiency formula is being updated.
  • CDCB health traits will be added and all traits will be combined into a Health Trait Index for an overall economic value.
  • The Feet and Legs Composite (FLC) formula has been modified to include Rear Legs Side View as a two-way trait with an intermediate optimum.
  • Fertility Index will now include Early First Calving and total weighting on all fertility traits will remain at 13 percent.
  • The weighting for Productive Life (PL) will increase by 1 percent. The 1 percent was taken away from Dairy Form.

Calving Ease, Stillbirth Evaluations Enhanced

The following updates will be implemented for calving traits. Genetic parameters were reestimated and will be updated on all calving traits.

  • Any herds reporting more than 95 percent of their calvings as category 1 (no difficulty) will be excluded from the phenotypic data used for genetic evaluations.
  • Calving ease categories 4 and 5 will be combined into a single category.
  • Estimated birth years will be used for missing Maternal Grandsire (MGS) birthdate information.
  • For both calving ease and stillbirth models, parity will be included in the random contemporary group effect and an interaction effect of parity-sex-birth year of sire and MGS will be included.

This last modification is needed to better account for the impact the increasing use of sex-sorted semen is having on the calving traits. The changes will result in less favorable trends in the calving traits and reranking of animals, especially in Daughter Calving Ease (DCE) and Daughter Stillbirth (DSB).

Jersey adds CDCB health traits and adjusts JPI™ formula

CDCB will be releasing Jersey health traits to help alleviate six costly health conditions impacting the breed. These will help build resistance against Displaced Abomasum, Milk Fever, Ketosis, Mastitis, Metritis and Retained Placenta.

The American Jersey Cattle Association board of directors adopted modifications to the Jersey Performance Index™ (JPI™). New traits included in 2020 JPI are the six Jersey health traits and two type traits, Rear Teat Placement Side View and Rear Teat Placement Rear View. The trait name Milk Density replaces CFP Milk. For the complete JPI formula breakdown visit

Zoetis Changes

Zoetis’ CLARIFIDE Plus test now includes dairy genetic evaluations for abortion, twinning, milk fever, cystic ovary and cow respiratory disease. These traits are expressed as genomic Standardized Transmitting Abilities (STA) with values centered at 100 and a standard deviation of 5. These genomic predictions for additional fertility and wellness traits provide both Holstein and Jersey breeders with valuable genetic information to increase individual cow performance and overall herd profitability.

Both Dairy Wellness Profit Index® (DWP$®) and Wellness Trait Index® (WT$®) have been adjusted to account for additional traits and recent evaluations from industry research.

Key Points

  • New traits included in the DWP$ formula include cow abortion and twinning for both the Holstein and Jersey breed. Cow respiratory disease and cystic ovaries have been added to Holstein DWP$.
  • Regarding the WT$ formula, cow respiratory joins the existing traits for both Holstein and Jersey variations of the formula.
  • Industry research has offered insight into the impact of specific traits. Feet & Legs Composite and Udder Composite, both indirect predictors of Productive Life, have been removed from DWP$ 2020.
  • Economic values for fat and protein are increased to reflect current and future milk pricing.
  • There is a greater negative economic value for Body Weight Composite (BWC).

In addition to new traits and reformulation of indexes, Zoetis has also updated the genetic base to offer the most valuable genetic predictions.

Based in Plain City, Ohio, Select Sires Inc., is the largest global A.I. cooperative and is comprised of six farmer-owned and -controlled local organizations in the United States. As the industry leader, it provides highly fertile semen, as well as excellence in service and programs to supply dairy and beef producers with the world’s best genetics.

®TPI is a registered trademark of Holstein Association USA. ™Jersey Performance Index and JPI are trademarks of the American Jersey Cattle Association.