Learn about EBVs in
Angus GROUP BREEDPLAN

Click here to go back to the full index.

(click on the links below to "jump" to the answer)

Estimated Breeding Values (EBVs)
10 - What is an EBV
11 - How are EBVs estimated
12 - What is so special about EBVs
13 - What different types of EBVs are there
14 - For what traits are EBVs available, and how are they measured
15 - What is the difference between an EBV of +45kg and +5kg.
16 - How accurate (reliable) are EBVs – What does Breedplan Accuracy mean
17 - Why do EBVs change
18 - What are Interim EBVs
19 - What happens to the EBV if incorrect information is submitted
20 - Can a person cheat the system
21 - How do EBVs enhance the pedigree
22 - How much of an EBV is transmitted to the progeny
23 - Can EBVs from different herds be compared
24 - What is the difference between Ratios, EPDs and EBVs

10 : What is an EBV (Estimated Breeding Value)

An EBV, as the name implies, is an estimate of the animal’s true breeding value. As EBVs are benchmarked they allow the animal to be fairly and directly compared to the breed(herd) benchmark, the current breed (herd) average, or with other animals from the same Breedplan analysis.

EBVs do not necessarily reflect the animal's observed performance, which is a combination of both genetic and environmental influences, rather they are an estimate of the genetic component of that performance.

The EBV is a value (number) which expresses the difference (+ or -) between an individual animal and the herd or breed benchmark to which the animal is being compared. Thus an EBV of +12 kg for 400-Day Weight means that the animal is genetically better by 12 kg at 400 days of age than the breed/herd base it is being compared to.

EBVs are reported in terms of actual product, for example, kg of weight or mm of fat depth

EBVs adjust for known environmental differences such as age of calf, age of dam and nutrition. This allows comparison of animals born in different seasons and years, and adjust for known genetic differences such as preferential joining of cows, and unequal competition between contemporary groups.

EBVs consider all the available information from relatives as well as the individual animal, and take account of the relationship (correlation) between traits, for example the relationship between birth weight and mature weight.

Development of an EBV is an ongoing process, for example ;

(i) at birth the EBV is estimated from the known performance of the calf's parents and close relatives. This is a preliminary estimate, useful but subject to change as siblings do not completely mirror the performance of their parents. At this stage, the EBV is the sum of half each of the parents EBV and is sometimes referred to as the mid-parent average.

(ii) at weaning, and at several later ages, the performance of the calf and its half-sibs is used to fine tune the original estimate.

(iii) finally the performance of the animal's progeny is used to further fine tune the predictive power of the EBV.

As each step progresses the EBV becomes a better estimate, as more information is available to estimate the EBV. Thus, the EBV becomes a more accurate estimate of the animal’s breeding value – for more information on accuracy, see Appendix A.

11 : How are EBVs estimated . . . . . . . . Go to Top

EBVs are estimated by:

(a) Firstly, adjusting recorded measurements for age differences between calves and for age differences between dams rearing those calves.

(b) Adjusted measurements are then compared to the average of a contemporary group of animals of the same sex, of the same seasonal age group "split", and having had the same management and nutritional treatment.

(c) Groups are then compared, using genetic linkage, to correct for the effects of non-genetic differences between groups. This allows comparisons of animals between different management groups and herds.

(d) Finally, the adjusted value is multiplied by heritability and correlation factors to derive the heritable component of adjusted differences between animals, that is, the EBV.

12 : What's so special about EBVs . . . . . . . . Go to Top

There is no magic about EBVs - they are simply a method of comparing animals for what they really are (rather than what they may appear to be), and for what their progeny are expected to be.

By accounting for a range of environmental (non-genetic) influences that cloud the genetic difference between individuals they increase the accuracy of selection decisions.

Special things about EBVs are ;

• they use industry standard language that means the same thing to all people. This allows better description and communication wherever and whenever cattle people talk about cattle.
• they estimate the amount of difference between animals that is heritable, i.e.. transferable to the next generation. We need to know this if we are to plan the marketing and production strategy of our herd in the future.
• they allow us to compare the performance potential of individual animals with other individual animals, and with the herd and/or average of the breed.
• they estimate differences between animals for traits that can't be detected by eye, e.g.. Milk,birth weight, intramuscular fat %. This is particularly useful information when selecting yearling bulls.
• they express genetic differences between animals in terms of commercial product that can be assigned a value when calculating the comparative net worth of breeding animals.
• they reduce the risk of selection decisions. Group EBVs have an accuracy rating that allows you to assign an objective risk factor to selection decisions made about animals.

They answer the question that every bull buyer needs to know - which is the best bull rather than which is the best fed bull - a cynic would say that if you don't have a defined breeding goal, or have never made an error of judgment when predicting the performance potential of breeding animals, then EBVs aren't so special.

13 : What different types of EBVs are available . . . . . . . . Go to Top

Three types of EBVs are available within Breedplan - Group, Interim and Within-herd EBVs.

Group Breedplan EBVs are estimated from the combined records of a number of herds who are genetically linked by the use of AI sires. A genetic base (0) for the breed is estimated as part of the Group Breedplan analysis and EBVs of individual animals are estimated relative to the breed base. The Group Breedplan analysis is conducted once or twice each year for participating breeds.

Interim Group Breedplan EBVs are estimated for herds that submit new data between Group Breedplan runs. They are in fact updated Group EBVs and are comparable with Group Breedplan EBVs.

Within-herd EBVs are estimated for herds who wish to see their data analysed separately or those whose herds are not linked into Group Breedplan. The within-herd genetic base (0) is estimated separately for each herd based on its first 200 performance records. The performance of related animals outside the individual herd is ignored. Within-herd EBVs are not comparable with Group Breedplan or Interim EBVs and should be confined to within-herd use only. cattle to buyers.
Angus Australia does not report any within-herd EBVs.

14 : For what traits are EBVs available, and how what do they mean.

Click here for a summary of the EBVs reported by Angus.

Click here for a detailed discussion and list of EBVs.

15 : What is the commercial difference between sires with EBVs for 400 Day Wt of +45 and +5

Click here for more information on using EBVs for making comparisons between animals.

16: How Accurate (reliable) are EBVs – What does Breedplan Accuracy mean . . . . . . . . Go to Top

EBVs are an estimate of the real breeding value of an animal. The estimate is made from analysis of all information that is currently available on the animal. Naturally, the more information that is available the more accurate the estimate will be and the less likely it will change as additional information becomes available.

The accuracy of an EBV reflects the amount of information used to estimate the animal’s breeding value, as a percentage of the amount of information needed to estimate its true breeding value with 100% certainty.

For example, if the only information available is the bull's own measured performance for 400-day Wt (a trait with a heritability of 30%, or 0.3), the accuracy of his EBV will be 55%. If 10 progeny records are added to the analysis the accuracy will increase to 74%.

Accuracy ratings are quoted in percentage terms from 0-99 for Group Breedplan EBVs, the accuracy being printed in italics adjacent to the EBV.

An accuracy of less than 35% indicates that not much direct information is available about the animal - it may be from relatives rather than direct observation, it may be from a correlated trait, and/or the trait has a low heritability. This EBV should be considered a preliminary estimate only and could change considerably as more substantial information becomes available.

EBVs for yearling bulls without progeny recorded are estimated from the record of the bull and/or its relatives - the accuracy of these “non-parent” EBVs will be in the range of 40 to 75%, with the higher accuracy EBVs reflecting a greater depth of information from relatives.

The EBVs of sires with recorded progeny are more accurate and more stable than the EBVs of “non-parent” bulls - progeny information is a better estimate of a bull’s breeding value than is his own performance. These EBVs will range in accuracy from 75% to 99%, the higher accuracy EBVs reflecting a greater number of progeny and/or daughters progeny records being available.

For more information about accuracy, click here

17 : Why do EBVs change . . . . . . . . Go to Top

Remember, an EBV is the best estimate made from the available information - as the information gets better (more plentiful), so does the estimate. Therefore it is only logical that the EBV of an animal will change with the addition of more information.

This additional information could come from weights taken as the animal grows, performance records of progeny, or from performance records of daughter's calves. Alternatively, the additional information could also come from close relatives.

In general the EBV of a sire or dam with many progeny will not change very much with the addition of new information, however the EBVs of a young sire can change quite markedly once its progeny start being evaluated.

These changes should be reassuring in that Breedplan is continuously refining the estimates as more information comes to hand, just as breeders do by eye as an animal grows and has progeny.

For more information about Accuracy, click here.

18 : What are Interim Group EBVs . . . . . . . . Go to Top

Interim EBVs are estimated for herds that submit new data between the Group Breedplan runs. Interim EBVs are in fact updated Group EBVs and as such are comparable with Group Breedplan EBVs.

19 : What happens to the EBV if incorrect data is submitted for analysis . . . . . . . . Go to Top

The EBVs will be incorrect. As for the pedigree, the integrity of an EBV is dependent upon the integrity of the information submitted. Accuracy of measurement is important, as is correct management group coding to allow for known environmental differences.

There are a number of checks and balances in the Breedplan system that identifies and questions performance information that falls outside expected boundaries.

20 : Can a person cheat the system . . . . . . . . Go to Top

Concern is often expressed about the possibility of a person "loading" the weight of an animal to increase its EBV. This could happen, but it would be an unwise thing to do.

There are checks and balances within the system that queries animals that are too far ahead of the pack, and secondly, as progeny are analysed in Group Breedplan, its failure to perform to expectations will be noticeable. Animals that are outside usual statistical boundaries are flagged as outliers and their EBVs are accompanied by a caution to that effect.

21 : How do EBVs enhance the traditional pedigree . . . . . . . . Go to Top

The pedigree was the first method of performance recording, based on the premise that "like begets like". The first cattle breeders knew that by recording the breeding of their cattle they could start to predict the breeding outcome (the breeding value).

Somewhere along the way the performance profile alluded to in the pedigree has become clouded.

There are now so many people breeding so many cattle in so many places that it is beyond comprehension for any person to relate to each individual animal (and where they rely on "word of mouth" to describe animals there has not been a common industry language to do so).

Also, because the use of show ring success as a de-facto measure of performance (with its associated intensive feeding) somewhat neutralise the original theory of ‘‘like begets like" - unless you buy the groom as well.

The pedigree is still, and always will be, the basis of performance recording but is more meaningful if the level of performance that we attach to it is free of environmental biases.

The EBV allows this to happen. It takes to account the known performance of relatives as well as the individuals performance, and it makes allowance for known environmental differences. As such, the EBV compliments the traditional pedigree, rather than competing with it.

22 : How much of the EBV is transmitted to progeny . . . . . . . . Go to Top

EBV stands for Estimated Breeding Value. An EBV is an estimate of an animal's breeding value for a particular production trait, for example, 400-Day weight. When the animal becomes a parent, half of its genes (breeding value) are passed on to the progeny. (the other half comes from the other parent)

Therefore, when bulls with different EBVs are joined to similar cows, the difference that can be expected in their progeny's performance will be half the difference in the EBVs of the bulls being compared.

Assuming they are joined to similar cows and produce under an environment that will not restrict growth potential, Breedplan estimates that the progeny of Bull A will average 1 kg lighter at birth and 10 kg lighter at 400 days than the progeny of bull B.

23 : Can EBVs from different herds be compared . . . . . . . . Go to Top

Group Breedplan and Interim EBVs can be directly compared between herds within the same breed Group Breedplan analysis as they relate to the breed base through the use of link sires.

24 : What is the difference between Ratios, EBVs and EPDs . . Go to Top

A ratio is used on a within-herd contemporary group basis only, with 100 used as the average of the group, and is not a genetic measure. Ratios can only be used for within-herd or mob comparison in a particular season. Ratios were the basis of performance recording programs but are rarely used today.

EBV is the term used in Breedplan and is an abbreviation of the term Estimated Breeding Value, which is the measure of an animal's own genetic value for a particular trait.

EPD is the term used in North American sire summaries and refers to Expected Progeny Difference, which is the animals genetic value as a parent - as the parent contributes 50% of its genes to its progeny, an EPD is in effect half an EBV. It is estimated using similar procedures to an EBV but EPDs are not comparable to EBVs because they relate to a totally different benchmark and cattle population.