Beef 2024 Report

Repronomics – Making selection more accurate for northern Australia

Genetics editor Alastair Rayner, 20/05/2024

Genetic progress is achieved through the combination of selection intensity and in the choice of the genetics available. Accessing genetics that are accurately described, and therefore able to increase confidence that the outcome will move progeny closer to defined breeding objectives is an essential requirement for success.

For various reasons, capturing the performance data essential to the process of description and development of breeding tools such as EBVs has been a significant challenge in northern seedstock herds.

While there are producers within the major tropical breeds of Brahman, Santa Gertrudis and Droughtmaster who have a long commitment to performance recording and the development of EBVs, the scale of data required to achieve high accuracies across traits of importance has limited the speed of development.

Dr Dave Johnston speaking at beef 2024

A significant step towards achieving greater understanding of the traits within these breeds that impact performance, as well as capturing data that has both sufficient scale and links across the breeds in the northern industry is the Repronomics Project led by Dr David Johnston.

This project has been underway across Northern Australia since 2013 and has been producing 1100 to 1200 calves per year.

Presenting an update on the project during Beef 2024 this month, Dr Johnston highlighted the importance of the project in not only linking data to current industry sires, but also in building data around new and emerging sires.

“Importantly, this project is about precisions recording,” he told the audience. “We have been measuring the economically important traits, those that are difficult or expensive to measure – and not done in industry herds.

“We have focussed on female production, and with the large Fixed Time AI breeding we have accurate dates of birth.  All calves are treated exactly the same and there is no culling, drafting, or sorting.  One in, all in,” he said.

While the focus of the project has been female reproduction, the steers from each year’s calf drop have been sent to grow out and be processed, with a focus on pasture finishing when possible.  These steers have also been the subject of intensive precision recording across grow out, finishing and processing.

The scale of data recorded across the project has been significant. In the 11 years of the program, there have been 12,000 calves generated. As presented in the image below, the data across cows, steers, and sires showcases the depth of data recorded to generate accurate breeding information that can be used by bull breeders and commercial producers.

Source: Repronomics & the Northern Steer BIN Project – Dr David Johnston AGBU

The impact of this data, and in particular the introduction of genomic information has rapidly increased the accuracy of a large number of EBVs.

Some lowly heritable and hard-to-measure traits have, as a result of the genomic data collected through the intensive and detailed recording, increased in accuracy by as much as 50pc and in some traits slightly higher.

The key take home message, apart from the need to continue to collect and grow the data associated with the breed populations, addresses the requirement for accurate data to make informed selection decisions.

The project has directly increased accuracy and as result breeders utilising EBVs now and into the future will benefit from the confidence to accurately select the most suitable sires to complement their breeding decisions.


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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