BREEDPLAN Estimated Breeding Values (EBVs) provide estimates of the genetic merit of an animal for a range of economically important traits. BREEDPLAN EBVs allow beef producers to assess and compare the genetic merit of animals.
This tip sheet provides an overview of how to interpret BREEDPLAN EBVs. For the purposes of demonstration, please consider the set of EBVs shown below.
What Does the EBV Mean?
EBVs are expressed as the difference between an individual animal’s genetics and the genetic base (historic genetic level of the population) to which the animal is compared. Furthermore, each EBV is reported in the units in which the measurements are taken (e.g. Weight EBVs are reported in kilograms). On average, half of this difference will be passed on to the animal’s progeny (the other half will come from the dam).
Please note that as each BREEDPLAN analysis has its own unique genetic base, only EBVs produced in the same BREEDPLAN analysis can be directly compared. A more detailed explanation is available in the Comparing EBVs from Different Analyses tip sheet, available from the Help Centre on the BREEDPLAN website.
How to Interpret BREEDPLAN EBVs
When considering BREEDPLAN EBVs, beef producers may:
- Compare to the level of genetic merit within the current population.
- Compare expected difference in progeny performance.
- Consider EBV accuracy.
1. Compare to the level of genetic merit within the current population
Comparing against the current levels of genetic merit allows producers to understand where an animal ranks within the evaluated population. This is important as most breeds have experienced significant changes in their genetic merit when compared to their historical genetic level (i.e. their genetic base) for most traits.
BREEDPLAN calculates the current level of genetic merit from the calving drop born two years prior to the current year (e.g. in 2023, the 2021 drop calves are used to define the current level of genetic merit). The reasons for using the calving drop born two years prior are two-fold. Firstly, given that some BREEDPLAN traits are not collected until the animals are rising two year old, this cohort has had the opportunity to be performance recorded for most traits when compared to younger animals. Secondly, many of the animals available for sale will belong to this cohort.
Comparison of each EBV against the breed average allows you to quickly identify whether the animal is below or above the average genetic level for each trait. This is often an easy first step when considering an animal’s EBVs as the breed average EBVs are displayed on both the web services area and in most sale catalogues.
If we consider the demonstration animal from above, comparison of its 400 Day Weight EBV of +52 kg with the breed average 400 Day Weight EBV of +35 kg indicates that the animal is 17 kg (i.e. 52 – 35) genetically heavier at 400 days compared with the average genetic level of the current population.
The comparison of each EBV against the percentiles bands allows for the identification of exactly where an animal ranks within the current genetic level of the population for each trait. There are two ways in which you can compare an animal’s EBVs to the current percentiles. Firstly, you can use the current Percentile Bands Table.
Using the same demonstration animal, the Percentile Band Table shown below indicates that this animal, with a 400 Day Weight EBV of +52 kg, ranks in the Top 5% of the population for growth at 400 days.
The second way to compare an animal’s EBVs to the current percentiles for the population is to use the EBV Percentile Graph. This graph provides a visual representation of where an animal’s EBVs rank within the population for each trait. Considering our demonstration animal once again, the EBV Percentile Graph shown below also indicates that this animal, with a 400 Day Weight EBV of +52 kg, ranks in the Top 5% of the population for growth at 400 days.
It is important to note that while for the majority of EBVs it is generally considered more desirable to rank higher in the percentile bands (i.e. on the right hand side of the graph), this is not always the case. Instead, the optimum EBVs will depend on your individual breeding objective(s), and the direction in which you are trying to move the genetic level of your own herd.
For example, a higher percentile for Mature Cow Weight indicates a heavier Mature Cow Weight EBV. For those producers trying to moderate the mature cow size of their herd, this may not be desirable. Similarly, producers running their cattle in environments that do not support high Milk EBV cows may seek animals with more moderate Milk EBVs. Equally, in situations where beef producers are trying to limit or actively decrease the rib and rump fat of their herd, an animal with more moderate Rib and Rump Fat EBVs may be more desirable.
The Breed Average EBVs, Percentile Bands Table and the EBV Percentile Graph can all be accessed online via the relevant web search system.
2. Compare Expected Difference in Progeny Performance
We have previously determined that the demonstration animal is ranked in the Top 5% of the population for 400 Day Weight. Using EBVs to compare the expected difference in outcome if two different sires are used in a herd gives us an understanding of what this means in real terms.
Consider the comparison of the demonstration animal to a second bull. The demonstration bull has a 400 Day Weight EBV of +52 kg, while the second bull has a 400 Day Weight EBV of +32 kg. Comparing these animals gives a difference in the 400 Day Weight EBV of 20 kg (i.e. 52 – 32). On average, half of the EBV difference will be passed on to the progeny of each sire (with the other half coming from the dam). Thus, it would be expected that the progeny of the demonstration bull would be, on average, 10 kg heavier than the progeny of the second bull at 400 days of age. Extending this to a single year’s drop of 50 calves, this difference equates to a potential production difference of 500 kg in live weight by the time the calves reach 400 days of age.
Please note that the above example assumes that both bulls are used over dams of similar genetic merit and breed, and that their progeny are run under similar environmental conditions.
3. Consider EBV accuracy
EBV accuracy provides a measure of stability of the EBV while also giving an indication of the relative amounts of information at that point in time that have been used in the calculation of that EBV. The higher the EBV accuracy, the lower the likelihood that the EBV will change as additional information on that animal and/or its relatives is analysed in future BREEDPLAN evaluations. Every EBV that is published by BREEDPLAN will have a corresponding accuracy figure, as shown for the demonstration animal.
As a general rule, animals should be compared on EBVs regardless of accuracy. However, where two animals have similar EBVs, the one with higher accuracy may be the less risky choice, assuming other factors are equal.
In practical terms, most young bulls at a bull sale can be expected to have similar EBV accuracy levels, as they will have had similar levels of performance recording and no progeny. Older bulls, especially AI sires with many progeny, will typically have higher EBV accuracies. Whether you choose to use a young bull with lower EBV accuracies or an older AI bull with higher EBV accuracies will be influenced both by your tolerance for risk and the individual mating scenario (e.g. you may choose higher accuracy Calving Ease EBV bulls for first-calf heifers).
Using BREEDPLAN information in animal selection
Although BREEDPLAN EBVs provide an estimate of an animal’s genetic merit for a wide range of economically important traits, they do not provide information for all of the traits that should be considered during the selection of functional cattle. Therefore, when making animal selection decisions, producers are encouraged to always consider BREEDPLAN information in conjunction with other traits of importance. These include pedigree, DNA test results, bull fertility results and visual assessment for structural soundness and temperament.
The A BREEDPLAN Guide to Animal Selection tip sheet, available from the Help Centre on the BREEDPLAN website, provides a best practice guide to using BREEDPLAN information as part of a balanced animal selection strategy.
For further information on interpreting BREEDPLAN EBVs, please contact staff at your BREEDPLAN processing centre.