Weekly genetics review: Understanding the language around EBVs

Genetics editor Alastair Rayner, 20/06/2023

OVER the next few months, thousands of bulls will be offered for sale across Eastern Australia.

The large majority of these bulls will be sold at auction, and for many attending these sales, there will be a strong sense of familiarity as the event gets underway.

Aside from the opening welcome from the vendor, the descriptions offered by auctioneers as each bull enters the ring should be familiar. Most auctioneers will highlight the attributes of the bull before them, focusing on physical characteristics or observable features.

Electronic data collection.

Many auctioneers also draw on the information offered in the bull’s catalogue entry, particularly drawing attention to genetic traits described by EBVs. There is no doubt this is an important and necessary part of the auctioneer’s role. Highlighting and emphasising a bull’s merits is key to securing a successful outcome for the vendor.

However, for those producers in the stands, or watching online, to make the best sense of these descriptions, there is a need to understand what EBVs are actually describing and what they mean for a breeding business that purchases and then uses a bull for breeding.

Among every sale attendance, there are always buyers who may not fully appreciate the purpose of EBVs and what they may mean, in practical terms, for their business.

There is a risk in the excitement of an auction that producers can mistake the auctioneers’ descriptions and use of EBVs as referring to the bull. It’s not uncommon to hear someone suggest that “he doesn’t look like his EBVs.”

That statement reflects the confusion some producers have and can lead to poor decisions on bulls or expectations about a bull that may not be realised.

Perhaps the most useful thing to remember is that EBVs belong to the progeny.

This line sums up the role of EBVs in the best possible way.  EBVs or Estimated Breeding Values are the predictions of an animals true breeding value. When considering a bull, the role of the EBVs is to help determine how his progeny are likely to perform within a breeding program.

Managing expectations

Managing expectation around a bull and its impact on a herd is more achievable when the role of EBVs is clear.

As an individual, a bull may well be one of the largest or most well-grown in the sale line-up, but have average EBVs for growth or other traits. The weight of the individual bull is a result of his own genetics and the environment he was raised in.

This environment is often the nutritional regime he was prepared on for sale. However the genetics he passes to his progeny should be the consideration for a potential purchaser. This is where EBVs can help look beyond the individual bull’s appearance, and consider what his influence will be on the next crop of calves.

Although this may seem a simple concept, there are times when producers overlook it and are then disappointed in the calves that are born next season. At the same time, it’s important to remember that EBVs are not all the same. Importantly, EBVs are reported in the units in which traits are measured – for example, kilograms for growth or millimetres for fatness. Knowing the difference in measurement can avoid one point of confusion.

A large number of EBVs can be used to help make informed decisions around improving a trait within a herd. Typically this may be useful to producers who want to improve a production trait, such as increasing performance in growth or carcase weight.

While improving these traits within is often the goal, producers also may have a goal of improving the number of animals within a herd that display more desirable traits.

Selection to improve the number of acceptable progeny displaying a trait, such as quieter temperament, improved calving ease and structural soundness can be supported by the information provided by EBVs.

Unlike measuring individual improvements, such as increased weight, the improvement in these traits is assessed by the predicted difference in the number of progeny with an acceptable score for the trait. Typically this may be seen as reducing the number of assisted calving or more calves with quieter temperaments.

Failing to appreciate that EBVs belong to the progeny as well as the fact EBVs can aid selection in different ways is perhaps one of the greatest causes for disappointment in bull purchases.

Mixing up an individual bulls’ physical appearance with genetic information is unfortunately a common mistake made across sales and can be easily done in the excitement of an auction.

Prior preparation in both viewing the individual bulls, as well as considering the breeding objectives of a program are two fundamental steps every producer should make ahead of a sale.

Not only does this help in finding the right bulls, but it can avoid the risk of mixing up an individual’s appearance with his potential to shape a herd into the future.


Alastair Rayner is the Principal of RaynerAg, an agricultural advisory service based in NSW.  RaynerAg is affiliated with BJA Stock & Station Agents.  He regularly lists and sell cattle for clients as well attending bull sales to support client purchases.  Alastair provides pre-sale selections and classifications for seedstock producers in NSW, Qld and Victoria.  He can be contacted here or through his website













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