National Selection Index

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Source: USA Cattle Genetics

Lifetime Net Merit $ (NM$) is the national selection index in the U.S. Net Merit predicts net profit over the lifetime of the animal’s average daughter, expressed in U.S. dollars. Net Merit ranks dairy animals through a formula that factors a combination of traits that are genetically and economically important to dairy herds.

The genetic contribution of several traits, like milk production, conformation, health and fitness, are factored into Net Merit. Traits are weighted based on their genetic impact on dairy farm profitability.

Net Merit was developed in 1994 by renowned USDA geneticists and is updated periodically with new traits and the latest research and economic values. Since 2021, Net Merit has included 39 individual traits for Holsteins. Not all traits are calculated for all breeds, so the Net Merit formula differs slightly between breeds.

Evolution of Net Merit

Genetic indexes are updated periodically to add traits, incorporate new research and reflect current economics.

Net Merit was introduced by USDA in 1994, as an index that combined the familiar production and type traits with two new traits, Productive Life and Somatic Cell Score. This new index blended fitness, conformation, and production – unique to indexes in most countries at the time.

Net Merit has been updated as new traits became available:

  • 2000: Udder Composite, Feet and Legs Composite and Body Weight Composite:
  • 2003: Daughter Pregnancy Rate
  • 2006: Calving trait sub-index
  • 2014: Heifer and Cow Conception Rate
  • 2017: Livability
  • 2018: Health trait sub-index
  • 2021: Heifer Livability, Early First Calving, RFI

Since 2021, Net Merit has combined 39 individual traits for Holstein animals. In 2021, three new traits were added to help breed cows that are more (feed) efficient: heifer livability, early first calving and residual feed intake . Economic values for all traits were re-evaluated and updated where needed.

In August 2020, the trait weightings in Net Merit were slightly adjusted in connection with the new phenotypic base for calving traits. Four calving traits – Sire Calving Ease, Daughter Calving Ease, Sire Stillbirth and Daughter Stillbirth – are included in Net Merit $ through a calving ability index (CA$).

As new traits are developed, Net Merit – and other selection indexes – will continue to evolve to include the most current and relevant research and economic values.