IGS - Sustainable Genetics for the Longterm

IGS: Sustainable Genetics for the Long-term

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A free tool to help commercial producers, marketers, and buyers objectively identify and share the profit potential of feeder calves.

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IGS Multi-breed Evaluation

IGS manages the largest multi-breed beef cattle evaluation in the world, using the most advanced technology to combine data and compare EPD across breeds for effective herd improvement.

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The commercial cattle producer is at the heart of International Genetic Solutions.

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Announcements and Updates

IGS Genetic Evaluation Updates from the IGS Science Team

To continue to improve genetic predictions is one of the main goals of the IGS genetic evaluation. Over the last year, several updates to models used in the weekly genetic evaluation have been investigated to be incorporated into the weekly genetic evaluation. As the IGS genetic evaluation has grown and expanded from historical partners, as well as the addition of new partners, the ability to run genetic evaluations within a week’s time frame has become difficult. One of the main goals of these updates was to increase the efficiency of evaluations; however, these upgrades are also to maintain or improve the accuracy of prediction of each evaluation. Within the evaluation there are three evaluations that will undergo updates.

The first analysis that will undergo updates is the growth evaluation. The growth evaluation produces EPD for Birth Weight, Weaning Weight, Yearling Weight, Average Daily Gain, Milk, and Maternal Weaning Weight. The changes that will be implemented are updates to the way that breed and years are incorporated into the genetic evaluation, and the method used to incorporate information from other genetic evaluations. Previously, breeds and years were incorporated by fitting interactions of these effects for each animal; with the updates, these effects will be separated. For the incorporation of information from outside genetic evaluations, IGS will use a new method that allows for better tracking of the changes that occur to EPD when this information is added to the evaluation.


The second analysis that will undergo updates will be the Carcass Weight and Ribeye Genetic evaluation. The CW/REA updates will include those described above for the growth evaluation as well as updated across-breed adjustments from the U.S. Meat Animal Research Center (USMARC) GPE program. This program helps to determine breed differences and is an important part of the carcass evaluations at IGS. These updated breed differences will also be applied in the Marbling and Backfat genetic evaluations, which is the third evaluation that will see updates. The updated across-breed adjustments from USMARC is the only change to the Marbling and Backfat evaluation.

Results of the Updates to Genetic Evaluations

When implementing updates to genetic evaluation, the IGS team undergoes a strict validation procedure to evaluate how potential changes will influence the predictive ability of the updated EPD. One of the most common ways this is done is by excluding a portion of the phenotypes, running an evaluation, and correlating the EPD from this run with the excluded phenotypes. For each of the evaluations, all animals that were born after 1/1/2020 were removed from the evaluation and used to test the predictive ability. The results for these comparisons are included in the table below.


Pearson correlation between parental average EPD and excluded phenotypes from animals in the IGS genetic evaluation that were born in 2020 or later. 


Updated Evaluation

Previous Evaluation

Birth Weight



Weaning Weight



Yearling Weight



Carcass Weight



Ribeye Area










         The results in the table above show that the implemented updates had the same or higher correlations than the previously implemented models. This would correspond — in most cases — to more accurate EPD for each of the traits. With the updates, some breeders may notice that the resulting EPD for animals may change, but the percentile rank for the trait may be similar. This is due to differences in estimated breed effects as part of the evaluation. While most traits will have strong EPD correlations between the previous and current evaluation, there will still be some re-ranking of animals because of these updates.

To help breeders see the results of the changes, a list of high-accuracy sires has been put together and is available below.  Based on member and IGS-partner feedback 2 additional updates were tested, validated and implemented. An updated base-adjustment and small change in how external EPD are incorporated were updated. IGS plans to fully shift to the updated growth and carcass models for an EPD release for the week of December 11th.


For information, or if you have questions about these updates, please contact Lane Giess, ASA Geneticist at lgiess@simmgene.com. These evaluations are going through the final beta testing process currently and are planned to be implemented in the near future.
IGS Carcass EPD Updates - Randie Culbertson

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