Genetic Evaluation

Wagyu National Cattle Evaluation

The Wagyu National Cattle Evaluation is now available at www.wagyu.org. This summary compiles the data collected and reported by Wagyu breeders, as well as the more recently collected genomic results, into the best possible predictions of each animal’s genetic merit.

Since the early 1980s, Expected Progeny Differences (EPD) have proven their effectiveness to make directional change in the herd performance for those traits for which EPD are computed.

Genetic evaluations express the genetic transmitting ability for an animal for the various traits listed. An EPD is a prediction of how future progeny of an animal are expected to perform in a particular trait relative to other animals in the analysis. EPD are especially effective for comparing cattle across herds and years (even within the same herd), a task not possible with phenotypes alone. Recent advancements in genomic technology has enhanced the accuracy of genetic predictions resulting in a breeder’s ability to make more accurate selection decisions.

The EPD for a given trait on each animal in the analysis is comparable to every other animal in the analysis and is reported as a plus or minus value in the unit which the trait is measured. It’s important to know that EPD are only comparable for within the population the EPD were computed.

Each EPD reported is accompanied with an Accuracy (ACC) value. ACC is a measure of reliability regarding the EPD evaluation for a performance trait. Accuracy is reported as a decimal number between 0 and 0.99: large values indicate greater accuracy and more certainty the EPD will show little change as additional progeny information is obtained.

Genomic Enhanced Evaluation

Genomic results are incorporated into the Wagyu genetic evaluation using the Single Step method. Single Step is the most accurate and reliable genetic selection tool available today. Incorporating genomic data into the genetic evaluation results in greater accuracy, especially for younger animals or animals with no or fewer progeny.

How to read the EPD information on an animal’s detail page

Helpful information for every animal is available on the EPD detail screen. The EPD is listed across the page for birth weight, weaning weight, yearling weight, maternal milk, and total maternal.

EPD: A prediction of how future progeny of an animal are expected to perform in a particular trait relative to other animals in the same analysis.

+/- Chg: This is the possible change value. Please see the discussion on accuracy for more information.

ACC: Accuracy, an indication of how close genetic estimates are to an animals true genetic breeding value as a parent.

% Rank: How does my animal rank when compared to the non-parent percentile rank table.

Prog/CG: The number of progeny meeting all edits and used in the genetic evaluation and the number of contemporary groups those animals are represented in. For Maternal Milk this number reflects the number of daughters in production (i.e. daughters that produced progeny meeting all edits and used in the genetic evaluation) and the number of contemporary groups those progeny were represented in.

Traits Reported

Birth Weight EPD (BW) The expected difference in average birth weight (pounds) of progeny. Birth weight reflects prenatal growth.

Weaning Weight EPD (WW) The expected difference in average weaning weight of calves. The evaluation reflects the genetic influence on pre-weaning growth rate.

Yearling Weight EPD (YW) The expected difference in average yearling weight of progeny. The evaluation reflects genetic influence on both pre-weaning and post-weaning growth rate.

Maternal Weaning Weight EPD (Milk) The genetic ability of a sire’s or dam’s daughters to express in pounds of weaning weight in her calves due to her maternal ability through mothering instinct and milk.

Total Maternal (TotMat) A value to predict the weaning weight performance of calves from an animal’s daughters due to genetics for growth and maternal ability. Total Maternal is calculated by adding ½ the Weaning Weight EPD to the Maternal Weaning Weight EPD.

Heritability’s and Genetic Correlations

Heritability indicates what proportion of the total phenotypic variation is due to genetic variation among individuals. Values of heritability can range from 0.0 to 1.0.  The remaining observed variation is due to environmental influences.

Traits with low heritability estimates are influenced more by environment than by genetics, thus genetic progress from selection may be slower. Traits with low heritability respond greater to the effects of crossbreeding. Since heritability is already an integral part of the EPD calculation, EPD reflect actual differences and require no adjustment.

Accuracy

Accuracy is an indication of how close genetic estimates are to an animal’s true genetic breeding value. Accuracy values are useful to breeders to determine the reliability of an EPD. Accuracy values range from 0.0 to 0.99, depending on the amount and quality of information that is known about an animal for any one of the reported traits. As the amount of information increases, the accuracy for that trait increases accordingly.

Click here for the "possible change" table (standard error of prediction) for various levesl of accuracy for the traits reported. You will notice that as the accuracy level increases, the possible change value decreases. Still, an EPD can change from year to year even though it may have a high level of accuracy. The point to remember is that the expected change of an EPD with a high ACC is correspondingly less than those of an EPD with a lower ACC value.

Possible Change is expressed as "+" or "-" pounds of EPD and can be described as a measure of potential change between the EPD and the "true" progeny difference. This confidence range depends on the standard error of prediction for an EPD. For a given accuracy, about 67% of the time an animal should have a "true" progeny difference within the range of the EPD plus or minus the possible change value.

For example, a sire with an EPD of +0.20 and accuracy of 0.50 has a possible change value of 6.4 pounds.  This sire’s “true” progeny value is within 6.4 pounds of +20 about 67% of the time. 

Percentile Rank

How does my animal rank when compared to the rest of the Wagyu population?

Ranking of an EPD in the breed is another useful tool for Wagyu breeders. The percentile rank tables available for active sires, active dams, and non-parent animals are an often-overlooked resource when making genetic selections.

If an active sire’s Milk EPD is equal to +2 lb., then by locating that EPD in the table for active sires and associating it with the percentile in the first column, the relative ranking to all active sires in the population can be assessed. In this case, the sire’s Milk EPD is in the top 25th percentile.

Non-parent percentile rank: rank for animal born in the last two years.

Active Dams percentile rank: Dams of animals born in the last two years.

Active Sires percentile rank: Sires of animals born in the last two years.

Why some performance information is not used in genetic evaluations.

Genetic evaluations are an analysis of the performance data reported for a population, in this case the population of Wagyu reported to the American Wagyu Association. Without performance data corresponding EPD cannot be computed.

For more information on collecting and reporting information to be used in the Wagyu National Cattle Evaluation please refer to the Wagyu Performance Guidelines.

Rules for publication of EPD

Herds enrolled in CAR (Standard) get EPD while herds enrolled in Verified will not have EPD published.  There are some exceptions to this rule, please read below.

EPD are published for animals with a minimum of a qualifying weaning weight submitted. Qualifying: reported weaning weight was used in genetic evaluation. (accuracy will be reported as a numeric value)
EPD published for animals with a genotype included in the evaluation. 

Pedigree Estimate EPD (PE EPD) are computed only if the Sire and Maternal Grand Sire (MGS) have EPD with an accuracy value. We don’t compute PE EPD if the Sire and/or MGS has a PE EPD or no EPD. In other words, we don’t use PE EPD to compute PE EPD. (accuracy will be reported as PE)

EPD will be published for ancestors (parents, grandparents, etc.) of descendants that have weaning records included in the genetic evaluation. Ancestors must also qualify for publication within the guidelines of Verified and Standard herds.

If an animal has an EPD computed meeting all requirements for computing and publishing an EPD but was bred by a verified herd and remains in a verified herd, EPD will not be published.

If an animal has an EPD computed meeting all requirements for computing and publishing an EPD, was bred by a verified herd but has been transferred to a Standard Herd, EPD will be published.

If an animal has an EPD computed meeting all requirement for computing and publishing an EPD, was bred by a Standard Herd but has been transferred to a Verified Herd or a non-member herd, EPD will be published.

If an animal has an EPD published based on the above guidelines that animal will continue to have EPD published regardless of future transfers.

In the case of leased females from a Verified herd by a Standard Herd.  EPD will be published for calves where the Standard Herd is listed as the breeder/owner of the calves.  EPD will not be published for the leased females.

Rules for Publication of EPD

Heritability and Genetic Correlations

Percentile Ranks

EPD Distribution/Breed Averages

Possible Change Values