What You Need to Know About the Updated $API and $TI

Key Updates: 

Same Strategic Goal, Modernized Tools: The previous indexes weren't wrong, and the genetic progress using them was real. Think of this update as upgrading from a flip phone to a modern smartphone—keeping the same job, but using better data and economic inputs. 

• Direct EPD Integration Replace Proxies: Instead of using correlated measurements (like predicting carcass weight from earlier growth), the updated models directly plug in actual EPD for Carcass Weight, Dry Matter Intake, Mature Weight, and Heifer Pregnancy. 

• Updated Economics and In-House Simulation: Built on an in-house customized simulation, real-word commercial production scenarios are modeled. Using historical CattleFax data projected across the next cattle cycle, all the major aspects of cattle production from cow and backgrounding assumptions to feedyard economics and carcass premiums and discounts are accounted for. 

• More Precise Accounting of Crossbreeding: The updated simulation evaluates animals in 10% Simmental increments. It directly reflects how purebred vs. hybrid bulls generate heterosis and complement an Angus-based commercial cow herd. 

$API (All-Purpose Index):

• Traits with High Emphasis: Stayability, Carcass Weight, Marbling, Calving Ease Direct, and Dry Matter Intake.

• Increased Focus on Cow Efficiency:  The model accounts for a fixed-land base– so mature cow weight stays balanced against available grass resources. This better balances cow maintenance costs against calf performance. 

• More than One Way to Profitability: Animals with different EPD profiles can still achieve a high $API– through terminal, maternal, or a combination of characteristics. 

$TI (Terminal Index):

• Traits with High Emphasis: Carcass Weight, Dry Matter Intake, and Marbling. 

• Direct Predictions Drive More Accuracy: Major profit drivers like Carcass Weight and Dry Matter Intake are now incorporated directly (rather than predicted through growth traits), which leads to a more accurate prediction of $TI. 

• Increased Focus on Pounds You’re Paid For: You’ll see a greater response in Carcass Weight and lesser response Marbling using the updated indexes compared to the previous. Marbling is still moving in a positive direction. 

What This Means for Bull Selection:

• Keep the Same Strategy: Use $API if you retain replacement heifers, and $TI if all calves are destined for the feedlot. 

• Focus on Percentile Ranks: Direct comparisons between old and new index values aren't meaningful—use the updated percentile ranks instead.