American Simmental Association is building the next $API & $TI – What do you need to know?

One of the biggest changes is that breed composition matters…

The updated indexes evaluate Simmental breed percentage in 10% increments rather than applying the same relative trait emphasis to every animal. Why does this matter? A 1/2 Simmental and a PB Simmental bull bred to Angus cows don’t contribute exactly the same expected amount of heterosis and breed complementarity. The new model may better account for those differences by adjusting the economic importance of individual traits based on the animal’s breed composition.

What does this mean when looking at your cattle and their indexes?

Expect $API and $TI values and potentially rankings to change when the updated indexes are implemented. That doesn’t mean an animal’s genetics have changed (they haven’t), however, the economic model and assumptions used to assign a value to them have changed. The indexes are becoming more specific to the production system, current economics, and breed composition being evaluated. This is why it is vitally important to ensure your actual phenotypes are being submitted to the association in complete contemporary groups and used in the genetic evaluation. EPDs are predictions built from all of the information available: phenotypes, pedigree and relationships, genomics, progeny data, and contemporary group information. Without actual phenotypes from your herd, the evaluation has less direct information about how those genetics are actually performing within your contemporary groups (helps account for environment). The more complete the data going into the evaluation is, the more opportunity we have to accurately describe the genetic differences that ultimately feed into $API and $TI.

Remember, the index is a tool that is meant to assist producers by including multiple traits within one simple to compare profitability driver. Two bulls can arrive at a similar $API or $TI through very different combinations of traits. Use the index to identify cattle with profit potential for your production objective, then look at the individual EPD traits to better understand how they arrived there.

The figures below show how relative trait emphasis differs between half-blood and purebred Simmental cattle in $API and $TI in the updated models.

Read more information on these changes from Dr. Jon DeClerck on the American Simmental Association website by clicking here.