3 - Buy the right bulls (or semen) to maximise progress toward enterprise profit while preventing inbreeding.

Guidelines for buying the right bulls

The purchased bulls, or semen for an artificial insemination program, need to provide the best value for the financial outlay. Regardless of the breeding program, the genetic value of a bull to an enterprise is based on how well its individual attributes fit the herd’s breeding objective.

At any point in time, EBVs are always the best estimate of the genetic potential for a trait. Accuracies that accompany the EBV value indicate how much information has been recorded for a particular animal for the reported trait. As more information is collected the accuracies improve (see Tool 4.04).

Use EBVs related to the traits identified in Procedure 1 as being important to the breeding objective to select the best bulls for the breeding program.

Measure the value of a bull by its fit with your breeding objective.

Relate the price you can ‘afford’ for a bull to the bull’s potential earning capacity. The most profitable bulls for your herd will be those with the greatest difference between predicted earning capacity and purchase price. These bulls may not always be those with the highest genetic merit.

Use the dollar index ($Index) value for all bulls you are considering buying to compare the prices. The index value is in dollars per cow mated so, as a guide to the bull’s value, multiply the index value by the likely number of cows he will be mated to in his working life. For example, the bull will be used for four years over 50 cows per year (200 cows). This value is a good guide for comparing bulls. A bull with an index value of 100 compared to a bull with an index of 50 is worth $5,000 extra (200 cows x $50 index points x 0.5). The index is an EBV so only half of the value comes from the bull.

This doesn’t set the price because it depends on the average for the sale and that depends on many other factors (Tool 4.05 has a better guide to valuing your bull purchase). It is important to note that the $Index value is the estimate of genetic merit for all of the supply chain. The cow-calf breeder will not realise all of the additional value for the higher $Index value as this is shared across all participants in the beef supply chain, including agents and processors.

Using this information you can select the bull with the highest genetic value for your herd’s breeding objective from those with the greatest difference between estimated earning capacity and purchase price. Tool 4.05 will assist you to avoid two common pitfalls when buying bulls:

  • paying too much for the apparent ‘super bull’ when economically the second best bull may be better value and better fit your operation/property
  • buying the worst bull in a sale catalogue because he was ‘cheap’ but then ‘paying’ for his poor performance.

When selecting bulls using $Index values it is important to also consider the individual EBVs and your herd situation. Table 3 demonstrates how two bulls can have very similar $index values (+$98 vs. +$101) but contrasting EBVs for individual production traits. For example, the bulls differ by 69kg for 600 day weight EBV (+50 vs. +119).

Table 3: Two widely used Angus bulls with similar Long Fed/CAAB index value but showing large variation in many traits.


Bull A

Bull B

Breed Average

Calving Ease Dir (%)




Calving Ease Dtrs (%)




Gestation Length (days)




Birth Wt. (kg)




200 Day Wt (kg)




400 Day Wt (kg)




600 Day Wt (kg)




Mat. Cow Wt (kg)




Milk (kg)




Scrotal Size (cm)




Days to Calv. (days)




Eye Muscle Area (cm2)




Rump Fat (mm)




Retail Beef Yield (%)




IMF (%)




Long Fed/CAAB Index




Ensure that your bull supplier is accurately recording all possible traits associated with traits that are economically important to your breeding program. If a bull breeder is recording all important traits, it will be reflected in the accuracies of the EBVs presented (see Tool 4.04). As a guide, young bulls should have all EBVs displayed (if EBVs aren’t displayed it generally means that trait hasn’t been recorded) with accuracies between 50-60% for weight traits. Traits of lower heritability will have lower accuracies.

Choosing the bull is the point at which inbreeding should be considered. In commercial herds a rule of thumb is to avoid successive bull purchases that have a common parent. Another way of saying this is to definitely avoid mating cows to bulls that have a parent in common. Other relationships are likely to be less severe. Inbreeding is a major impediment to genetic improvement by bull breeders so most times they will try to introduce new genetic lines on a regular basis.

Also, remember that the physical ability of bulls to sire many calves is a primary consideration. The selection of bulls for maximum fertility based on structural soundness and libido are discussed in Procedure 1 of Module 5: Weaner throughput. Management can also play a large role in bull fertility. Prevention of infectious reproductive diseases is outlined in Procedure 1 of Module 6: Herd health and welfare.

Check bulls for structural soundness at purchase and annually before mating.

The Australian Poll Gene Marker test

Unlike many traits of importance to beef producers, whether an animal is horned or not is completely controlled by genetics - environmental factors have no impact on the occurrence of horns.

The Australian Polled Gene Marker test has recently been developed and can identify some of the genes controlling the trait, with high accuracy for some breeds. The test was developed in tropically adapted breeds, though results suggest it may be applicable to some Bos taurus breeds. Through the Australian Poll Gene Marker test, producers have a tool to identify breeding animals which will consistently produce polled progeny as well as carriers of horned genes.

The test reports on the likelihood of an animal being homozygous ‘true polled’, or heterozygous poll (meaning the animal may appear polled but generate progeny that are horned). If the aim of a breeding program is to increase the frequency of polled genes and reduce the proportion of horned animals, the use of ‘true polled’ sires (carrying poll genetics only) will allow the desirable polled gene to dominate the herd more quickly than using a heterozygous polled sire (carrying both poll and horn genetics but visually appears polled).

As with any trait, breeding for higher proportion of polled animals is only one consideration in making a balanced selection decision. 

Read the Australian Poll Gene Marker test fact sheet.

What to measure and when

Predict the value of bulls for improving enterprise profitability.

When a new bull purchase is being considered and before mating each year:

  • assess the genetic merit of prospective bull purchases
  • estimate the earning capacity of bulls based on the index value and the projected pattern of use (number of cows per year x number of years used), see Tool 4.05
  • assess structural soundness of the bull battery
  • assess the accuracy of information given to you by your bull breeder. Tool 4.04 has information that is recorded on sale bulls and the subsequent accuracies associated with the EBVs.