This spring, alongside the routine annual updates of economic assumptions and genomic scores, significant enhancements will be implemented in the Sire Evaluation Report and National Cattle Evaluation. These updates will be effective Friday, May 24, and aim to refine the accuracy and performance of the American Angus Association’s genetic evaluations.
The Sire Evaluation Report is the biannual report run to update the main and supplemental sire lists, breed averages, percentile ranks and more.
Carcass weight, ribeye area and fat
The enhancements include updates to the carcass model and its genetic parameters, including heritability estimates and genetic correlations.
This carcass model update involves the modeling of the ultrasound fat thickness and ultrasound ribeye area records in the evaluation. Previously, records for animals of different sexes (bulls, cows, and steers) were modeled as separate traits. In 2017, cows and steers were condensed into one trait, and now the Angus Genetics Inc. (AGI®) team will condense the ultrasound traits again by placing all three sexes into one singular ultrasound phenotype. This reduces the model from nine traits to seven traits.
“Our research shows accounting for the sex within a contemporary group yields the same prediction accuracy as the previous model while reducing the model’s complexity, which is important for an on-time delivery of the weekly genetic evaluation,” said André Garcia, senior geneticist with AGI®.
An updated model also means an update to the genetic parameters inside this genetic evaluation.
“This is necessary because we are changing the make-up of the model, which warrants updated variance components. Not to mention, over time the population changes and evolves due to selection,” Garcia said. “As more phenotypes are collected, the variances, heritability estimates, and genetic correlations change. By updating genetic parameters regularly, we can accurately estimate the genetic variation in the population and the relationships between traits.”
In multiple trait models, as is the case with the carcass evaluation, accurately estimating the genetic correlations between traits is crucial to take advantage of the accuracy that correlated phenotypes bring. This is particularly true of ultrasound records, Garcia said.
Continuous research and the implementation of regular updates ensure accurate and unbiased genetic evaluations are delivered on time. These updated estimates will be seen online, effective May 24, and in the 2024 Fall Sire Evaluation Report.
Core update
Also taking effect on May 24, the core update is related to how genomic relationships are calculated inside of the genetic evaluations.
“This is not a new update, and the most recent core update was implemented in May 2021,” said Kelli Retallick-Riley, AGI® president. “Since then, genotypes of more than half a million animals have been added to the weekly evaluation. With the 2023 addition of Angus Australia’s genotypes to the World Angus Evaluation, that number has increased by more than 800,000 for a total of over 1.8 million genotyped animals.”
With all genotypes being used in the evaluation, Retallick-Riley said the core update ensures a good representation of the genotyped population and provides optimized convergence for the models and computing time efficiencies, allowing AGI® and the Association to maintain a timely delivery of weekly genetic evaluations.
Learn more about the motivation behind core updates on Page 62, “A Good Problem to Have,” of the Angus Journal’s May issue.
Economic assumption updates
Annually, the bio-economic model driving the Association’s $Values undergoes annual updates, utilizing data from CattleFax. Economic assumptions are averaged over the previous seven years for stability, with the 2024 assumptions based on data from 2017 to 2023.
“This long-term perspective mitigates market volatility and aligns with the average cattle cycle,” said Esther Tarpoff, director of performance programs.
The May 2024 updates account for rising weaned calf sale prices and ration costs. In May 2023, the average weaned calf price was $167 per cwt. for steer calves and $152 per cwt. for heifer calves. The update increases the average calf price to $182 per cwt. for steer calves and $164 per cwt. for heifer calves.
Ration costs in the feedlot also increased from $199 to $225 per ton, affecting feed costs in the cow-calf sector. These changes influence the outcome of the maternal weaned calf value ($M), where calf price relative to cow cost stays the major revenue driver.
The average price per hundred for a fed steer delivered and dressed increased from $192 per cwt. to $206 per cwt. from 2023-2024. This shift redirects economic weight in beef value ($B) towards weight traits like carcass weight and postweaning gain and away from grid premiums, which only saw a slight increase. Despite the significant increase in fed cattle prices and minimal changes in quality premiums, overall changes in $B are minimal.
Producers might notice a slight re-ranking favoring cattle excelling in feedlot value $F over those at the top of the $B ranks to their $G, Tarpoff said. Some individual animals experienced changes, with the largest decreases in $M, $B, and $C being -$4, -$6, and -$9, respectively across the 4,146 current sires.
“Changes in $Values will be less likely due to economic assumption updates and more likely due to changes in individual EPDs from other evaluation updates,” she said. “Overall, updates didn’t substantially alter individual $Values, with economic assumption updates resulting in correlations above 0.99.”
Annual genomic scores update
Genomic scores are also updated annually. This process involves updating SNP effects for each trait based on additional phenotypes and genotypes from the previous year.
The May 2024 update includes a larger reference population (n= 1,593,532), which genomic scores are ranked against. With an increased number of genotyped animals, the reference population grows, leading to re-ranking. Genomic scores are a by-product of genetic evaluation and are updated alongside EPDs.
“It’s preferable to use genomically-enhanced EPDs for selection decisions, with genomic score updates not affecting EPDs themselves,” Retallick-Riley said.
For more information about updates specific to phenotypic traits, read the “By the Numbers” column in the Angus Journal’s May issue.
Phenotypic trait updates
Since 2021, phenotypic traits submitted to Angus Herd Improvement Records (AHIR®) were listed in a variety of places, including the performance registration certificate and EPD/Pedigree Look-up. Adding these traits provides visibility to members submitting phenotypes on animals and continues to fuel genetic evaluation.
Taking it one step further, starting on May 24, some phenotypes will be bolded in the list while others are not. This differentiates what phenotypes are included in the genetic evaluation and which traits are not. The phenotypes included in the genetic evaluation helped to inform the predictions for EPDs.
Heifer Pregnancy contemporary groups
Updates made to the heifer pregnancy contemporary groups aim to better characterize weather and environmental conditions that could affect heifer pregnancy outcomes.
“Contemporary groups play a significant role in any genetic evaluation, accounting for non-genetic sources of variation that affected an animal’s phenotype,” Garcia said. “This update leads to a more accurate and less biased heifer pregnancy genetic evaluation.”
The “By the Numbers” column in the Angus Journal’s April issue dives into further detail about updates to the heifer pregnancy genetic evaluation.
– Written by Sarah Kocher, Angus Communications
