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What Are EPDs

They are evaluation tools if you will, which allow anyone wishing to use scientific historical data to make an informed decision about the reproduction potentials of his herd.

Brief History of EPDs

First we must study a brief history of their origin. The concept of EPDs was first introduced to seedstock beef cattle producers nearly 30 years ago with the first publication of a National Sire Evaluation. An Expected Progeny Difference (EPD) is an estimate of the genetic merit of an animal as a parent and is reported in the normal units of measurement such as pounds or centimeters.

Initially when introduced, cattle producers showed skepticism at the concept; however, over the years this has changed to widespread acceptance. Today EPDs are the genetic selection tools of choice for most cattle producers in the U.S.

 What Do EPDs Provide?

An EPD value predicts the genetic transmitting ability of an animal as a parent. The genetic makeup of an animal will never change, but the amount of information we know about that animal can.

Additional information can change our predictions about that animal as a parent.

Obtaining & Evaluating EPDs

EPDs are obtained from genetic evaluation systems based on Best Linear Unbiased Prediction (BLUP) theory. Genetic evaluation systems based on BLUP theory use performance records, such as birth, 205-day and 365-day weights, along with pedigrees, to estimate EPD values. These systems simultaneously estimate EPD values for direct and maternal traits, incorporate all relationships among animals being evaluated, and use information from correlated traits in multiple trait evaluations. These genetic evaluation systems estimate EPD values on sires, dams and young (non-parent) animals that are comparable across herds within a breed.

Information Used in EPD Estimate

An EPD estimate on an animal incorporates the animal's records and its parent records, progeny records and sibling records, the animal's genetic ability and the environment in which the animal was raised. To help separate genetic ability from the influence of environment, producers supply information about the environment in which an animal was raised through the formation of contemporary groups.

Contemporary Group

A contemporary group is a group of animals born and raised together under the same management. Producers separate cattle into contemporary groups by determining which calves were raised in similar conditions and grouping them together.

Contemporary groups are also determined by sex, so heifer calves are compared with heifer calves, bull calves with bull calves and steers with steers. Calves remaining in the same contemporary group after birth must also be measured for production record keeping on the same day.

EPD definition - The expected difference (in trait units, usually expressed in lbs. or %) in performance of a bull or cow's progeny when those progenies are compared to a progeny of a sire or dam with an EPD of zero for the trait in question. EPD values are relative. They do not indicate absolute levels of performance. Rather, they can be used to compare expected progeny performance of different bulls or dams.



Understanding & Using EPDs

Now for the meat of our discussion: how to understand and use EPD’s.  Below you will find a condensed version of the Red Angus Association’s guide provided to ranchers for their use in utilizing EPD information.



The Ranchers’  Guide to EPDs


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 15 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 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.



EPDs: What, Why & How?

Understanding ACCURACY



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.



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).


EPDs are only as good as the data used to calculate them. This fact led Red Angus to implement Total Herd Reporting (THR) over two decades ago, and Red Angus continues to be the only breed association to mandate THR for the collective Red Angus cowherd. In a nutshell, THR requires the annual production of every Red Angus cow and the performance of every calf raised through weaning to be reported. Only THR allows for the accurate calculation of fertility and longevity traits, which are the largest drivers in cowherd profitability. With THR, we know which daughters that were exposed to breeding delivered a calf. With THR, we can better predict which bulls’ daughters are able to bring a calf to the weaning pen year after year. Ranchers make more accurate selection decisions and ultimately more profit when they buy bulls whose EPDs are backed by THR.


Red Angus' commitment to Total Herd Reporting allows for the measurement of each female’s lifetime production history; from being exposed to breeding as a yearling, to measuring females’ productive

lifespan. Implementing these tools into your selection decisions will have a long-term impact on your operation’s profitability.



Calving Ease Direct (CED) - predicts the probability of calves being born unassisted out of 2-year-old heifers. Producers want live calves - born unassisted. Selecting on actual birth weight is flawed; it is influenced by non-genetic factors such as nutrition and weather (ambient temperature). While BW EPD

removes these non-genetic factors, Red Angus’ CED EPD is the best predictor of calving ease. The CED EPD includes variation in BW plus other influential genetic factors such as gestation length, calf shape, etc.



4 = Top 50%

7 = Top 25%

9 = Top 10%


Heifer Pregnancy (HPG) - predicts the probability of heifers conceiving to calve at two years of age. Many breeds offer genetic predictions of yearling bull scrotal circumference as an indicator of age of puberty. While puberty is a prerequisite, many factors influence pregnancy rate. Red Angus’ HPG EPD offers a tool which selects for what is economically relevant to ranchers - pregnant




10 = Top 50%

11 = Top 25%

13 = Top 10%



Calving Ease Maternal (CEM) - predicts the probability of a given animal's daughters calving unassisted at two years of age. Replacement heifers should be able to calve on their own. Red Angus' CEM EPD offers the industry's most reliable prediction to address that concern. It includes not only the predisposition for a female to calve unassisted, but also her contribution to her calf's traits (birth weight, calf shape, etc.) that make it more likely to be born unassisted.



5 = Top 50%

7 = Top 25%

9 = Top 10%



Maintenance Energy (ME) - predicts differences in daughters’ maintenance energy requirements and is expressed in Mcal/Month. Recognizing that 70% of cowherd feed costs are burned up in maintaining weight and condition, Red Angus’ ME EPD allows for the selection of bulls whose daughters will require less feed; thus, reducing cowherd expenses. Include selection pressure for ME EPD to ensure feed costs don’t get out of line when selection is made for greater performance and production.




1 = Top 50%

-3 = Top 25%

-6 = Top 10%


Stayability (STAY) – predicts the probability of a bull’s daughters remaining productive until at least six years of age. Why six? That’s how long it takes a female to breakeven given all the expenses of development.


Red Angus’ Stayability (STAY) EPD is a selection tool to improve overall cowherd efficiency through reducing replacement rate. Cows that stay productive, are problem free and last longer mean a larger percentage of heifers can be cash cropped, instead of developed as replacements.


How is Stayability EPD Calculated?

THR provides the foundation for a reliable Stayability EPD. Once a female enters the productive cowherd she is monitored annually for her productive ability. Only females that produce a calf every year up until at least six years of age are given a positive observation. Females that miss a calf or are culled for any reason including soundness, production, disposition, body condition, etc. are given a negative observation. Mandatory collection of Stayability observations from all Red Angus herds provides ample data for the prediction of a bull’s ability to sire Ranch-Tested – Rancher-Trusted cowherds.


Improving Stayability enhances cowherd profitability by increasing the percentage of females that deliver pounds and value to the weaning pen without extra labor or feed – and do it year after year.


Stay EPDs

11 = Top 50%

13 = Top 25%

15 = Top 10%


Traits that add weight to your bank account!


Realizing the vast majority of commercial operations’ revenue comes from the sale of pounds, Red Angus strives to provide industry-leading genetic predictions for growth. This can only be achieved through the implementation of Total Herd Reporting. Red Angus further ensures the reliability of performance data through the use of data filters, which eliminates data outside biological norms. The net result of these efforts - no surprises on pay day.


Birth Weight EPD (BW) - predicts the difference, in pounds, for birth weight, and is also used in the calculation of Red Angus' Calving Ease Direct (CED) EPD.



-1.0 = Top 50%

-2.4 = Top 25%

-3.7 = Top 10%



Weaning Weight EPD (WW) - predicts the difference, in pounds, for weaning weight (adjusted to age

of dam and a standard 205 days of age). This is an indicator of growth from birth to weaning.



56 = Top 50%

63 = Top 25%

69 = Top 10%




Yearling Weight EPD (YW) – predicts the expected difference, in pounds, for yearling weight (adjusted

to a standard 365 days of age). This is an indicator of growth from birth to yearling.



83 = Top 50%

95 = Top 25%

106 = Top 10%


Milk EPD (MILK) - predicts the difference in maternal production of an individual animal's daughters as expressed by the weaning weight of their calves.



20 = Top 50%

23 = Top 25%

26 = Top 10%


Total Maternal EPD (TM) – predicts the rancher's actual observation of weaning weights of calves raised by an animal's daughters. TM includes the daughter’s milk EPD plus half of her genetic contribution to her calf's weaning weight EPD. The formula for TM EPD is:TM EPD = Milk EPD + 1/2 (WW EPD)



48 = Top 50%

52 = Top 25%

56 = Top 10%




Bred-in Carcass Value...

Red Angus is preferred among producers who retain ownership of their calf crop.


This demand is driven from consistent feedyard performance combined with reaping premiums from value-based grids. Furthering the mission of providing genetic predictions that directly impact producer profitability, Red Angus recently added Carcass Weight (CW) and Yield Grade (YG) to its arsenal of ERTs. Incorporation of these selection tools have the power to take your profitability to the next level.



Marbling Score (MARB) - predicts differences for carcass marbling score as expressed in marbling score units. Higher marbling scores are positively correlated with higher carcass quality grades.



0.41 = Top 50%

0.57 = Top 25%

0.69 = Top 10%



Yield Grade (YG) - predicts differences in USDA Yield Grade score and is expressed in USDA Yield Grade units. YG EPD is calculated using the genetic predictions of CW, REA and FAT EPDs. The reliability of Red Angus’ YG EPD is enhanced by using both ultrasound and actual carcass data in the calculation

of REA and FAT EPDs.



0.02 = Top 50%

-0.05 = Top 25%

-0.11 = Top 10%




Carcass Weight (CW) - predicts differences in hot carcass weight and is expressed in pounds. Because Red Angus’ CW EPD is a multi-trait model which includes birth, weaning and yearling weight data, the prediction is not subject to culling bias. Thus, it provides a more reliable EPD as compared to only using actual carcass weights. This computation allows for the use of weights taken on ~57,000 animals per year as compared to only ~1,500 animals per year with actual carcass weight observations. Increased Carcass Weight tends to detrimentally affect Yield Grade; the calculation of which also includes Rib Eye Area and Fat Thickness.



18 = Top 50%

28 = Top 25%

37 = Top 10%


Rib Eye Area (REA)
predicts differences of carcass Rib Eye Area

between the 12th and 13th rib. Increased Rib Eye Area has a beneficial effect

on Yield Grade which also includes Carcass Weight and Fat Thickness.




0.10 = Top 50%

0.25 = Top 25%

0.39 = Top 10%



12th Rib Fat Thickness (FAT) predicts differences for carcass fat

depth over the 12th rib, as expressed in inches. Increases in fat thickness

has a detrimental effect on Yield Grade.



0.00 = Top 50%

-0.01 = Top 25%

-0.03 = Top 10%



Building a cowherd?

Combine low-expense traits (ME EPD) with acceptable revenue traits to breed efficiency into the cowherd.

Improve fertility with selection pressure on HPG EPDs.

Sleep through the night by selecting high CEM EPDs.

Improve longevity and lower replacement rates by selecting higher-than-average STAY EPDs.


Breeding virgin heifers?

Select for CED EPD as the most meaningful predictor of calving ease. Red Angus’ CED combines birthweight and other factors affecting calving-ease scores.


Selling calves or yearlings?

Heavier payweights may be achieved by selecting higher WW EPDs, but make sure heavier is what you want. Heavier weaning weights mean heavier payweights for calf feds. However, for those who background their calves, too much weaning weight could translate into yearlings that are too heavy when they enter the feed yard, and finish too heavy. Overshooting performance goals can be just as detrimental as falling short.

Enhance your reputation - improve traits that impact feeder profits, such as carcass traits and post-weaning gain (YW).


Retaining Ownership?

Docile and fast starting, Red Angus are easy to start on feed and keep on feed.

Balance YW EPD of potential bulls with the existing cowherd to pinpoint needed improvement for post-weaning gains.

Increase payweight with selection for improved CW EPD.


Selling on a Grid?

■ Fine-tune marbling (MARB), rib eye area (REA) and back fat (FAT) EPDs to target value-based grids.

■ Target YG 1 & 2 premiums and avoid YG 4 discounts by applying selection pressure on YG EPD.

■ Optimize carcass weights to increase payweights while avoiding discounts for heavy weight carcasses.

■ Balance Carcass EPDs against existing cowherd genetics:

• Cowherds of higher Continental influence may require additional selection pressure on MARB EPD to improve quality grade.

• High-percentage British cowherds typically benefit from selection pressure to reduce YG and increase CW.