Australian Sheep Breeding Values

Australian Sheep Breeding Values (ASBVs) have been serving the industry well, providing genetic potential information for many breeds. The number of traits available continue to increase, including meat eating quality with the added value of the industry reference populations and genomics.

ASBVs are an invaluable tool for all sheep producers (commercial and stud) wanting more lambs, better growth, better carcases, and ultimately, better returns. For traders, sourcing animals with known genetic potential can have a significant impact on turn off time and weight.

The industry started with within flock breeding values and once there was good linkage across flocks, progressed to across flock breeding values (ASBVs) for each breed. This allows comparison of all Poll Dorsets for example, provided they were recorded with LAMBPLAN. More recently there is the terminal and maternal analyses where all terminal sires (e.g. Dorsets; Suffolks; Texels; etc) have been combined so it has been possible to compare say the carcase performance of a potential Suffolk sire with a Poll Dorset. Similarly with the maternal sires, you can look at perhaps milk and growth performance of Border Leicester sires with an East Friesian.

Composite self-replacing enterprises are now more prevalent in Victoria, made up of many breeds and combination of breeds. Sheep Genetics has been developing a new combined analysis that will include all maternal and terminal sires into one, which is being released in stages over 12 months.

The new combined maternal and terminal analyses will give more opportunity to identify animals with top genetic potential for selected traits across breeds (noting Merinos and Dohnes are not included in the combined analysis).

However, there will be changes in the ASBVs and some breeds/studs may be affected more than others.

New baseline

Currently ASBVs represent the change from recording in 1990. The new analysis will change the baseline to 2000 – so that means the ASBVs will most likely be lower because they will show the genetic change since 2000 not 1990.

For example, if we look at the current 50 percentile for maternals in October 2025 – post-weaning weight is 11.84 kg. This means the ‘average’ maternal sire now is 11.84 kg better for growth (or that much heavier at the same age) than in 1990. For Poll Dorsets the 50 percentile for post-weaning weight is 15.14 kg. Both increases indicate the significant genetic progress that has been made since 1990. The new analysis will therefore show the change since 2000, and the combined analysis will allow comparison across these breeds.

There will be other changes to some ASBVs as a result of combining all terminal and maternal breeds caused by linkages, heterosis and changes to the analysis criteria. But the ranking is unlikely to change – the best will be the best in most cases, but it will take time to adjust to selecting rams with sometimes lower ASBVs than in the past.

For example, a Border Leicester ram in the Maternal analysis currently has ASBVs for growth (as post weaning weight - pwt) of 13.4, maternal weaning weight (mwwt) as 2.3, eye muscle depth (pemd) as 1.3 and fat (pfat) as 1.25. In the combined analysis, this ram is 1.7 for pwt, 3.1 for mwwt, 0.4 for pemd and 1.8 for fat. The ram is still well very good for these traits but what he is being compared to has changed.

Consider your system as well as the traits

For composite breeders who are interested in traits and not breeds, the new ASBVs will enable a wider range of comparable animals for selection. For producers who run a terminal system and are only interested in select terminal sires, the choices will be the same but will need to be aware of the changes and that maternals are also in the analyses. Sheep Genetics have taken the opportunity in doing this new analysis to review and make improvements to the way the evaluation works which should offer benefits for purebred animals.

Maternal sires are always a bit more complex because a maternal breed that is used for crossbreeding (e.g. Border Leicester or Friesian) is quite a different enterprise to a self-replacing maternal composite flock.

A maternal sire used in a cross-breeding enterprise (usually with a Merino) is often selected for traits that improve the mothering, growth and carcase of the progeny. This system benefits from some hybrid vigour from the cross which predominantly improves the reproduction rate of the ewe progeny. A terminal sire is then often used to further improve growth and carcase attributes. The move to maternal composites takes away the reliance on purchasing replacements and so select for a range of traits from more breeds, without the benefit of hybrid vigour.

Both systems have a place, but whatever the system, producers need to realise the changes will affect some breeds more than others. If you are interested in specific breeds only, to look across studs that sell that breed and use the percentile charts. This will help to understand the changes to the breed ASBVs whilst still accessing the best genetics for the traits you want.

For this buying/selling season, ram buyers will still be able to select rams using the terminal or maternal analysis. Stud breeders will be able to show what the changes mean for their flocks by accessing both. By April 2027 only the combined analysis will be available.