Insights into the IGS Calving Ease Update
by Jon DeClerck, PhD, ASA EVP
Why Updates Happen
Genetic evaluations evolve because science evolves.
Just like your phone or computer receives software upgrades, our tools improve as new data and better methodology become available.
Past approaches weren’t wrong—today’s tools are simply more effective.
Routine updates like this are standard across breed associations and the beef industry. Every major genetic evaluation employs comparable updates as part of their ongoing efforts to remain competitive and ensure the highest degree of accuracy. Our goal with updates is always the same: To improve the predictive power of International Genetic Solutions (IGS) EPD.
A Unified, Science-Driven Decision
Before any update is released, the system undergoes validation exercises to test how well the model works and how accurately it predicts real‑world results. These tests use proven, peer-reviewed methods to provide unbiased measures of performance.
After that, the evaluation underwent review and approval by all 25 IGS partner associations, with input from the geneticists and consultants who support many of those organizations. Each partner had the chance to look at how the update affected their own cattle, but no one could see the impact on other breeds or associations.
This was not an American Simmental Association (ASA) only decision, but a system-wide agreement across the world’s largest and most trusted multi-breed genetic evaluation, reflecting consensus on both the science behind the update and the need to implement it now.
A Commitment We’ve Always Made
When I applied for this position, I pledged to continue the long-standing philosophy of the American Simmental Association:
Profit Through Science
From our founders in 1968 who rejected show-ring fads, to the leaders who navigated Focus 2000 in Columbia, Missouri, our Association has always prioritized objective performance evaluation. We have always believed that genetic evaluation must be rooted in data, not preference, not politics, and not pressure.
A primary reason for forming IGS was to be honest about where our cattle truly stand in the larger beef industry. And we remain committed to that transparency today.
What Changed in This Update
This is the first major calving ease model improvement since the adoption of BOLT more than a decade ago. The IGS team has made this update a top priority for the past couple of years. With over 22.5 million cattle and more than 750,000 genotypes in the IGS database, shifts were expected.
The update centered around three scientific advancements:
- Maternal Genomic Markers
This is a significant upgrade.
Previously, models could not incorporate marker effects for calving ease direct and calving ease maternal simultaneously. New software capabilities and innovations developed by Theta Solutions, LLC now allow us to include those markers, giving a more complete genetic picture and improving prediction accuracy.
- Improved Handling of External EPDs
When we bring in EPD from other associations (e.g., Angus), we apply a base adjustment. We refined that process, improving the consistency and accuracy of the evaluation.
- Updated Breed-by-Decade Modeling
With millions of phenotypes spanning seven decades, grouping cattle is necessary for proper statistical power. We revised assumptions about genetic progress across breeds, reflecting that breeds have made similar improvements in calving ease over time. This refinement again enhanced model accuracy.
What This Means for Accuracy
Collectively, these improvements enable the calving ease model to explain roughly 12% more of the phenotypic variation observed in CE. This does not mean every individual animal’s CE EPD accuracy increased by 12%; rather, the IGS CE evaluation as a whole is more effective at distinguishing genetics that improve calving ease from those that do not.
Your cattle did not change.
But we believe the tool that describes them has been improved.
Think of it like medical advancements. Twenty years ago, evaluating heart health often required major surgery; today, the same assessment can be done with a minimally invasive scope. The heart didn’t change, the diagnostic tools did. The earlier approach wasn’t wrong; we simply have better technology available now.
Why This Matters
The IGS evaluation exists to serve our breeders, but also the broader commercial cattle industry. Our responsibility is to ensure our EPD predictions reflect biological reality as accurately as possible. That is how we protect the credibility of our breed and maintain our role as leaders in objective genetic evaluation.
Across the entire IGS population, the average CE change was 0.3 units. As many of you have observed, the Simmental population experienced a larger shift, averaging about 1.6 units for purebred Simmentals.
The fact that this update had a more pronounced effect for ASA underscores our commitment to science-based evaluations. Regardless of the outcome, we follow the data because it reflects our mission to serve the commercial beef industry. That dedication to objectivity and integrity is exactly what our IGS partners and the industry rely on and expect from us.
Why Release Now
There is never a “perfect time” for releasing an update.
Delaying until summer:
- Would not reduce the magnitude of any shifts
- Would only postpone the adjustment
- Would leave breeders using outdated predictions for over half a year
Releasing now ensures members make selection, mating, and marketing decisions using the most current and accurate information available today.
We recognize the timing challenges, but this decision was made because it best serves the membership, IGS partners, and the cattle industry.
Moving Forward
I want to reaffirm my full confidence in the IGS team and in the science underlying this update. Updates like these are part of routine best practices in genetic evaluation. Many of you will recall similar refinements with carcass and growth traits prior to my tenure at ASA, and this process will continue.
Looking ahead, the IGS team is reviewing docility and fat traits, and we remain committed to leveraging the best science and statistical models to enhance prediction accuracy. These enhancements strengthen our evaluation, increase long-term confidence in our predictions, and reinforce the credibility of the Simmental breed within IGS. They demonstrate
- That ASA does not manipulate outcomes.
- That we remain committed to objectivity.
- That we are fully aligned with all IGS partners in advancing science-based predictions.
Thank you again for your engagement and your commitment to this association. Please continue reaching out with questions—Dr. Jackie Atkins, Dr. Elizabeth Dressler, Dr. Ben Crites, and I are here to help you make sense of these changes and support your success moving forward.