Rancher’s Guide to EPD’s

by the American Red Angus Association

Based on the concept of Economically Relevant Traits (ERTs), producers are equipped with tools that allow for selection on traits that directly impact profitability. These tools simplify the selection process, and arm producers with the ability to better identify range bulls whose genetics will more positively impact profitability.

Red Angus delivers technology in a producer-friendly package. Red Angus’ inclusion of genomic data into EPDs provides genetic predictions with unsurpassed dependability. Expressing these EPDs on a multi-breed base allows for simplified selection decisions regardless of desired breed composition. EPDs are the most reliable predictors of an animal’s true genetic merit. As the only major beef breed to mandate Total Herd Reporting (THR), Red Angus EPDs have the built-in advantage of being calculated from 20 years of complete contemporary group data. EPDs have “fast-tracked” beef cattle improvement and removed much of the guesswork associated with selecting range bulls.

EPDs

EPDs predict differences in progeny performance, and are calculated from comparisons within Contemporary Groups. (A group of calves that were born in the same year, calving season, herd, and are of the same sex and were fed and managed alike.)

EPDs have a clear advantage over less sophisticated predictors such as actual weights or within-herd ratios. Actual and adjusted weights are affected by environment, nutrition and management. Contemporary group ratios are an improvement, as they account for these environmental variables. However, they do not incorporate comparative performance data on related individuals in countless herds throughout the country. Red Angus EPDs account for these sources of variation in performance as well as mating bias (which cows were bred to which bulls). The power of these genetic predictions is multiplied by including every contemporary group from herds in the entire Red Angus breed.

Compare EPDs across breeds.
All animals in Red Angus and Simmental’s multi-breed database are described using the same language. That is, their EPDs are published on the same multi-breed base and scale. Selection for Growth (BW, WW, YW, Milk) and Carcass (MARB, YG, CW, REA, FAT) EPDs will be greatly simplified as commercial customers will be able to directly compare these EPDs across breeds, as well as registered hybrids/composite seedstock.

Absolute performance is not predictable... Relative performance is. For Example: Suppose your old herd bull has a yearling weight EPD of 50. You buy a new bull with a yearling weight EPD of 70. How much will the new bull boost your calves’ yearling weights?

The Answer…
We cannot predict how much performance will change from one year to the next because of varying environmental conditions (rainfall, temperature, available feedstuffs, etc). However, we do know this: the calves raised in the same contemporary group sired by your new bull will have the genetics to weigh an average of 20 pounds more at 365 days of age as compared to calves sired by the old bull.

Understanding ACCURACY
Red Angus EPDs are often presented with a corresponding accuracy value, which measures the strength of the relationship between the genetic prediction (EPD) and true genetic value. Accuracies are reported as a decimal number from zero to one. As accuracy value approaches 1.0, the EPD is “accurately” or closely estimating the true genetic merit of an animal for a given trait. Although low-accuracy EPDs are less reliable when compared to those of proven sires, independent research demonstrates EPDs to be the most meaningful indicator of animals’ true genetic merit. While “perfect” accuracies of 1.0, are never achieved, many heavily used Red Angus sires have accuracies greater than 0.9 (some as high as .99).