Weekly genetics review: Dealing with bull sale supplementary sheets

Genetics editor Alastair Rayner, 18/07/2023


THERE are many defining images that spring to mind in describing a typical bull sale.

Aside from packed stands and agents gesturing to signal a bid, the iconic image is often producers standing in pens with bulls closely scrutinising sheets of paper.

Sale days can be an information overload for many producers. Aside from the catalogues which often arrive in the mail well ahead of the sale, there are the additional supplementary sheets to collect and then completion of registration requirements to bid before the bulls can even be inspected.

The addition of the supplementary sheets can often be a tipping-point for many prospective bull buyers, who struggle with the information they have at their disposal. The comprehensive amount of information available in a catalogue, ranging from EBVs to genetic test results, pedigrees and breeders’ comments can overwhelm and in some cases cause everything to become a blur in the mind.

It’s no surprise really that the simplicity of a supplementary sheet appeals to producers struggling to process the vast amount of information.

Supplementary sheets generally follow the same template. The individual bulls will be listed along with the last weight recorded before the sale, along with data collected at a recent scan, often providing raw measurements of fatness at the P8 and rib, Eye Muscle Area (EMA), scrotal size and often Intramuscular Fatness (IMF %).

While this information is useful, it is essential to keep in mind a very basic fact. This data refers entirely to the bull that is standing in front of the breeder. The expression of those traits such as weight, fatness and IMF are a result of the genetics of that bull’s sire and dam, and the subsequent nutrition and environment that he has experienced over the previous 18 months to two years (depending on his date of birth).

In understanding this, it is vital producers don’t then try to use the raw data provided in the supplementary sheets as a basis for their expectations for what that bull may do within their herd.  Many producers have been caught out by using raw data in the expectation that what they have seen on sale day is exactly what they will get when that bulls calves arrive in the next calving.

With this in mind, many producers often ask about the role of this raw data and the supplementary sheets at sale day.  More fundamentally, the question is what do they do with this information and how should it be used?

In simplest terms the data provided is useful in helping learn more about the bull as an individual in order to make decisions about his suitability to a breeding program.

The size and weight of the bull may well be a determining factor for producers who intend to join him with smaller (or larger) females.

His actual size and weight determine his daily feed requirements. It can be useful to decide if a bull is too big and too heavy for the nutrition on offer at home.

There have often been issues associated with large, heavy, and well prepared bulls losing weight rapidly in a new environment, simply because their nutritional needs were greater than expected or able to be provided by a different pasture and feeding program.

Fat scans can also be helpful as producers consider the muscularity of bulls in sale pens.

The “Breeding for Profit” manual published by the QDPI several years ago described the issue of fatness stating that:

Fat, and particularly subcutaneous fat (fat just under the skin), can often deceive many a bull buyer into thinking a bull is well muscled when he is actually poorly muscled but well fed.

Having access to recent scan data may be helpful for some breeders who are seeking to avoid those bulls that are fatter and less muscled than others in the sale catalogue.

Ultimately decisions on bulls and their ability to contribute to changes within a breeding herd shouldn’t be made on the basis of the raw data in the supplementary sheets. These choices should be made carefully using the EBVs that have been published.

If there are two similar bulls that have been chosen on the basis of the EBVs, then the supplementary sheet could be handy as a guide on things such as the bull’s fatness or weight as factors shaping the individual’s ability to start work this season.


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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  1. Brett McCamley, 19/07/2023

    You intimate that muscling is preferred over fat when making your selection observation of future sires. In fact, in the commercial operation, fat is required to grade in a chiller assessment. The vast majority of commercial operators are now looking for an animal that lays down an even coverage of fat, generally in double figures, no matter the breed, as a guide to what that bull can produce. Fat coverage and IMF% is also a good guide to your heifer/female constitution once in the breeder herd. But you also need to understand each breeders feeding regime for their sale bulls.

    Thanks for your comment, Brett. Worth noting, Beef Central services a national audience, and as such, some of Alastair’s comments may relate more specifically to circumstances and breeds seen in southern Australia, rather than the north. Editor

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