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.”

ASA will host a virtual town hall on Tuesday, September 29th at 5:30 PM MST covering the updates to $TI and $API. The webinar will include a short presentation by ASA staff. Members will have the opportunity to submit questions through the meeting platform, which will be answered by ASA staff.

A meeting link will be posted here.

As we have shared more information about the updated $API and $TI, three changes have received a lot of attention: $API places downward pressure on mature cow weight, carcass weight carries more relative emphasis, and marbling carries less relative emphasis than before.

In many ways, those changes reflect a larger challenge facing the beef industry. We are being asked to produce more pounds of product while also keeping cow size, maintenance cost, and forage use in check.

That creates an obvious tension. If we want more carcass weight, are we simply going to make mature cows bigger too? And if moderate, cost efficient cows are important, why not build an index that stops at weaning and focuses solely on the cow-calf producer?

These are fair questions that highlight what I like most about the updated $API: it balances cow efficiency with downstream terminal value.

The ASA Board of Trustees recently met and selected their nominees for the upcoming Trustee election. Physical nomination ballots were sent, and the online voting portal on Herdbook is now open.

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