Simmental
& SimGenetics Cattle
Data Driven.
Member Focused.

Update 9/16/2026

by Dr. Elizabeth Dressler, ASA Lead Geneticist

Economic selection indexes are a valuable tool for selection and mating decisions. One major benefit is that selection indexes combine several traits into one number that estimates expected progeny profitability for a specific production system.

When you open a sale catalog to compare two bulls, economic indexes are designed to help answer a practical question: “Which bull is expected to sire the more profitable set of calves within this production system?” ASA publishes two economic selection indexes: the all-purpose index ($API) and the terminal index ($TI). These indexes help Simmental breeders make more informed decisions by bringing the economic importance of several traits together in one easy-to-use tool.

Why is ASA updating $API and $TI?

$API and $TI are valuable tools for Simmental breeders and have helped make meaningful genetic progress in the breed. If you are a Simmental breeder who has used $API or $TI over the years, you have likely seen the value of these selection tools in your own herd. In other words, the previous indexes were not wrong. Simmental breeders have made progress using them, and they have served the breed well. ASA is making key updates so the indexes will be even better selection tools. The beef industry has changed in recent years, and our technology and ability to analyze data have also advanced significantly. Together, these changes give ASA an opportunity to build on what has worked and make the indexes even more accurate at predicting progeny profitability.

Dr. Jon DeClerck covered the reasons for updating $API and $TI in more detail in his recent articles, including his article titled “Building on Progress: Why It’s Time to Update $API and $TI.” As he explained, “Updating $API and $TI is not about moving away from what has worked. It is about building on that success with better data, better technology, and a better ability to model the biology and economics of today’s cattle industry.”

A few weeks ago, I wrote about why it is time to update $API and $TI. The short version is that three things have changed: the economics of the cattle business, the technology available to model profitability, and the traits we can now measure and predict directly.

Before digging deeper into what has changed within the indexes, it is probably worth taking one step back and asking a more basic question:

What exactly are $API and $TI trying to do?

The Profit Through Science Podcast
Now streaming on Spotify and Apple Podcasts

Episode 2 available now: Preview Fall Focus 2026. A big-picture look at where the beef industry is headed.

The American Simmental Association (ASA) is pleased to welcome Marcia Jedry as Director of Finance & Operations. Marcia brings extensive leadership experience in association management, finance, operations, marketing, communications, and nonprofit leadership. Her career has included executive leadership roles with organizations across Idaho, providing her with a diverse background in organizational management and a strong understanding of the relationships and partnerships that drive successful associations.

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