Genetic Evaluation Maintenance: Core 21– On May 28, 2021, the Association, with the guidance of Angus Genetics Inc (AGI), will perform required maintenance on the genetic evaluation with updates to the genetic evaluation’s core. Core is a subset of animals representing the entire genotyped population, allowing for the Angus’s genetic evaluation to utilize a large number of genotyped animals.
Core was implemented at the advent of Single Step in July 2017 but has not been updated since. With over 20 million registered, pedigreed animals and almost 1 million genotyped animals recorded, the Association and AGI are taking the necessary steps to update the core, ensuring an accurate representation of the genotyped population.
Core 21, the updated core, is the part of the genomic relationship matrix (GRM) that is directly inverted and then is combined with all other parts to calculate the inverse of the GRM for all animals. Core 21 is a representative sample of the genotyped population which best captures the total variation of the GRM, or the relationships determined among animals using genomic results, which optimizes the evaluation.
Overall, breeders will find correlations and rankings between animals before and after the implementation of Core 21 are very high. In fact, all traits across the entire population saw correlations above 0.99. However, even with a 0.99 correlation, it is no surprise that some animals will show a resulting change in EPD after implementation of Core 21. These changes are due to the better representation of the variation of genomic relationships inside Angus’s weekly genetic evaluation.
Genotyped animals with EPD accuracies <0.50 will experience the most change. For example, for weaning weight EPD, the largest decrease for WW EPD is -12 and our largest increase in WW EPD is +15. These changes are normally distributed. Therefore, even though some large outliers are changing by a significant degree, most of the changes are centered around zero. Though seldom, some high accuracy animals will experience large changes. These changers are generally related to high-use sires that were born after 2016 that have many genotyped progenies added to the evaluation since that time. To learn more about the core maintenance update, read Andre Garcia’s latest By The Numbers column in Angus Journal by clicking here.
Annual Economic Assumption Update: Each year, the costs and revenue prices underlying the bio-economic model, which drive the Association’s $Values, are updated. This annual update is assembled using data provided by CattleFax. The economic assumptions implemented each year are the average of the previous seven years of data – the 2021 economic assumptions are based on prices recorded from 2014 to 2020. This year’s biggest changes are in terms of Ration Cost and Days on Feed. In May 2020, economic assumptions based on the average of 2013 to 2019 were implemented with an average ration cost of $194. The exchange of 2013 and 2020 costs where 2013 was a year of high feed costs at $323/ton, 2020 replaces it at $163/ton, reducing the average to $171/ton. With that average days on feed for both calf-fed and yearling-fed cattle increases from 236 and 165 days to 240 and 168 days, respectively. Because these two factors offset one another in terms of economics, little re-ranking in both Feedlot Value ($F) and Beef Value ($B) will occur due to these changes.
Overall, the above updates did not result in a significant change to individual $Values. Updates to economic assumptions resulted in correlations above 0.99. Even with these very high correlations, some individual animals can change with the largest decrease in $C being -24 and largest increase in $C coming in at +26. Overall, breeders can expect sires to rank very similarly when the 2021 assumptions are implemented. For more information on $Values, visit www.angus.org/nce/valueindexes.
Annual Update Genomic Scores: While GE-EPDs are updated on a weekly basis, genomic scoresare only updated once a year. This annual update will take place on May 28, 2021. The update includes a larger reference population, which genomic scores are ranked against. With that, genomic scores are a by-product of the genetic evaluation, so as EPDs are updated, genomic scores will be updated as well. It is always preferable to use the GE-EPDs when making selection decisions, and the updates to these genomic scores will not affect the GE-EPDs themselves. To learn more about GE-EPDs, visit www.angus.org/AGI/GenomicEnhancedEPDs.pdf.