Use BreedObject to develop an appropriate breeding objective for the herd and calculate a selection index
This procedure covers:
- guidelines for setting the breeding objective
- breeding objective
Guidelines for setting the breeding objective
Correctly setting the breeding objective for the production system and target market is critical. It defines the target for genetic improvement that maximises profit for the beef enterprise. If the breeding objective is inappropriate, the wrong emphasis may be placed on important traits (eg carcase weight or mature weight versus weaning rate).
The breeding objective lists the animal traits that affect enterprise profitability, and gives an estimate of the relative economic importance of each trait. The economic value of changing each important animal trait is calculated from financial and production data, preferably when setting the enterprises direction (see Module 1: Setting directions), but other approaches can be taken, such as using BreedObject.
The breeding objective is based on the ‘ideal’ animal for a particular enterprise
To initiate calculation of a breeding objective, the dollar value of one unit of change in each trait in the objective (eg 1kg of sale weight) is calculated while holding all other trait values constant. This calculation is the economic value for the trait. BreedObject software performs this calculation using costs, returns and current performance levels (eg sale weight 400kg or weaning 85%) for the enterprise recorded using a questionnaire.
The outcome of developing a breeding objective should be a list of traits with their relative importance to your herd profit. BreedObject is the most precise way to calculate the economic values of desirable traits, but other methods can be used. You can still use the procedures in this module if you have determined the breeding objective without using BreedObject.
The economic values may be informative when choosing between breeds as an indicator of what traits to look for in a potential new breed, but knowledge of the genetic merit of breeds is essential to make informed decisions. Changing breeds will make quantum changes in some traits and the relativity between traits will be quite different. If deciding to change breeds or switch to a crossbreeding program, you may need to recalculate the breeding objective because the average performance levels of the cattle will change.
BreedObject calculates a dollar index ($Index) for animals specific to the breeding objective
Once the economic value is calculated, BreedObject uses known relationships between objective traits and estimated breeding values (EBVs) to calculate an appropriate weighting for each EBV that will optimise progress towards the defined objective. Multiplying EBVs for individual animals by the weightings, then summing these values gives the $Index value. The $Index value is a measure of the genetic merit of the individual animal for the breeding objective; it describes how well an individual animal suits its intended purpose.
A number of breed societies have generic, market-based breeding objectives and selection indexes available on their websites, allowing commercial breeders to search for bulls that fit within their target index specifications (see Tool 4.1). These indexes are a very good guide as the objectives for many enterprises will be similar, and will rank animals similarly.
The breed-based indexes have been calculated from very good industry feedback on the costs, returns and trait performance levels of the production system and target market. Most commercial producers would be well advised to start with one of the standard breed society indexes and modify their selection procedures using a process described in Procedure 4.
A breeding objective
The breeding objective is the ‘ideal’ animal the producer aims to breed.
It is a genetic description that includes all the animal traits affecting profit (eg sale weight and weaning rate), as well as the importance of each trait to achieve a change in profit (economic value). The breeding objective is specific to the intended market, the production system, management environment and the current level of herd performance (eg current sale weight and current weaning percentage).
Economic considerations need to include all the factors affecting returns and costs. Returns are affected by the weight and price per unit of beef product sold, and premiums and discounts applying to particular traits. Cost of supplying extra feed, time taken to manage calving heifers and the cost of labour are examples of cost factors.
Using this economic data, the value of one unit of change in each trait (eg 1kg of carcase weight) of the breeding objective is assessed. Table 1 shows an example of the traits included in the objective and the economic values of traits. Economic values allow for the time taken until traits are expressed (eg carcase weight of steer progeny occurs sooner than lifetime reproduction occurs in female progeny). The benefits passed on to later generations are also included. Negative values can occur (eg for cow weight), meaning that a 1kg increase will reduce profit. In this case, the extra costs of feeding the cow due to an increase in weight are greater than the extra value of the carcase when the cow is finally culled from the herd.
Table 1 also provides the relative economic values, which indicate the importance of each trait for breeding for intended market, taking into account the scope for genetic improvement (ie heritability). In this example, for a Bos taurus breed supplying a high quality export market, marble score is most important, then weaning rate, calving ease and sale weight. Trait importance can change for different production systems and market endpoints. It can also differ among breeds addressing similar markets. These relative values are often depicted graphically (Figure 1). These graphical representations of trait importance for all breed indexes are available on the BreedObject website: www.breedobject.com
All this information can be combined into one figure, the $Index, to rank and compare bulls on their combined genetic worth for the production system and intended market. Use this as the primary ranking for bulls being considered as sires, after which you should consider the underlying component traits in any bulls of interest to the breeding program.
|Trait||Economic values||Relative economic values|
|Sale liveweight – direct effects||0.614 $/kg||14.7 $|
|Sale liveweight – maternal effects||0.421 $/kg||3.0 $|
|Dressing percentage||9.568 $/%||9.9 $|
|Saleable meat percentage||7.808 $/%||11.6 $|
|Fat depth (rump)||0.000 $/mm||0.0 $|
|Cow weaning rate||2.239 $/%||17.9 $|
|Marbling score||50.913 $/score||22.2 $|
|Cow survival rate||2.880 $/%||5.0 $|
|Cow weight||–0.203 $/kg||–6.1 $|
|Calving ease – direct effects||2.778 $/%||15.9 $|
|Calving ease – maternal effects||2.778 $/%||6.4 $|
What is an EBV?
An animal’s breeding value can be defined as its genetic merit for each trait. While it is not possible to determine an animal’s true breeding value, we can estimate it. These estimates of an animal’s true breeding value are called estimated breeding values, or EBVs.
EBVs are expressed as the difference between an individual animal’s genetics and the genetic base to which the animal is compared. EBVs are reported in the units in which the measurements are taken (eg kilograms for weight EBVs). A value of +12kg for 40-day weight means the animal is genetically superior by 12kg at 400 days compared with the genetic base of the relevant cattle population. On average, half of this difference will be passed on to the animal’s progeny.
BREEDPLAN considers all the pedigree and performance information that is available on an animal and its relatives to produce an estimate of an animal’s breeding value (ie an EBV). BREEDPLAN is a similar technology to that which has been used by the pig, poultry and dairy industries to make such dramatic production changes over the past few decades. It has worked wonderfully well for those industries, and works just as well for the genetic evaluation of beef cattle.
BreedObject is a tool for formalising breeding objectives and $Indexes that can help you breed more profitable cattle. It uses BREEDPLAN EBVs. It helps you target the type of commercial herd performance you need from animals for a given market production system, and it helps you identify seedstock that will be best suited to this. BreedObject $Indexes are intended for use by stud and commercial beef producers.
BreedObject collates the BREEDPLAN EBVs on bulls into a single EBV, the $Index, which describes how well a bulls suits a particular purpose. If you are interested in more than one type of commercial production purpose, you will be interested in more than one $Index.
BreedObject is customisable to any commercial herd market production system. For any given system, the first step is to complete a trait-level analysis of which factors affect profit. In a second step, use BreedObject to assess what emphasis is justified (to address the target) on the different EBVs that are available for the animals. These differing emphases are reflected in the $Index value calculated for each animal.
Differences in the $Index values calculated describe how animals are expected to benefit production system profitability when production is for the described purpose. The $Index is an EBV for profit for this production purpose. Ranking seedstock on their $Index sorts them for their progeny's expected profitability for the targeted production system.
BreedObject $Indexes assess genetic potential for progeny performance. They tell you what to expect from progeny on average. They don't describe how bulls themselves will perform, for example during joining. Issues of structural and reproductive soundness need to be considered in the usual way. BreedObject on the web provides easy access to all vendors so you can discuss these and other matters.
Developing your own $Index is achieved in two stages. First, use your knowledge to assess trait importance for the market production system you visualise. Then, determine the $Index of EBVs that best targets the identified trait importance.
Identify the commercial market production system to be targeted
This is the most important step. Your knowledge and ability to describe this system is the key to customising your index. Think about how animals will be used, over what type of cows and in which environment, and the likely levels of production, costs and prices. Then complete the short, multiple-choice questionnaire online. Aim to use estimates and levels that apply under good management that you think will be relevant into the future.
Some other points to consider:
- Bull breeders – focus on the commercial market production system/s of your main clients.
- Bull buyers – focus on the commercial market production to be addressed by your main class of sale animal (eg steers).
- Focus on the whole production system, in general; from cow–calf production to finishing.
- Consider making separate cases where it is difficult to decide between competing systems or views of the future. It can be helpful to see how animals rank for several purposes.
Assess trait importance
The information you provide through the questionnaire is used to assess the impacts that trait changes will have on profit. These are examined using a detailed herd model. All traits that directly affect costs or returns are considered. The assessment for each trait assumes levels of the other traits remain unchanged.
The results on trait importance take into account the assessed effect on profit and the amount of genetic variation available for change in a trait. These results are illustrated graphically and are automatically available for your breeding objective.
Construct the best $Index
Once the trait importance has been determined, the $Index of available EBVs that best correlates with this is automatically constructed.
This $Index takes account of the assessed economic importance of traits, of the genetic variation for – and associations among – traits, and of any other herd-specific information you provided.
Results on the percentage emphasis being applied on each EBV are illustrated graphically, and are automatically available for your $Index.
Using your $Index
Your $Index is immediately and automatically available for use online. The applications are the same as those available to any other $Index. It can be applied to the EBVs of animals in your own herd to help with selection, to the EBVs of published sires, or to the EBVs of animals in sale or semen catalogue listings to help with bull or semen purchase.
Any $Index you derive is automatically added to the list of $Indexes that are available to you. These $Indexes are easily selected or de-selected for display, and your $Indexes can be edited or deleted at any time.
BreedObject is a commercial software available at www.breedobject.com
The software allows calculation of tailored breeding objectives using a simple questionnaire, or more sophisticated calculation of a breeding objective and an index by using a consultant. Once developed on a password-secured site, the personalised index can be applied to any animals listed on the BREEDPLAN system.
What to measure and when
Annually, review any changes that have been made to your production environment or target market. If significant changes have occurred, you may need to reset your breeding objective.