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Using South African Simbra Selection Indexes

Selection indexes assist beef producers to make selection decisions that take into account the relevant growth, carcase, fertility and efficiency attributes of each animal to identify candidates whose progeny will be the most profitable for a particular commercial enterprise. Selection indexes provide an overall indication of an animal’s genetic value for profit in a specific production system/target market and are calculated based on weightings placed on individual traits that are deemed to be important for that production system.

The weightings are calculated using BreedObject software that analyses all sources of costs and income for the production system represented by each selection index. As such, selection indexes account for both sides of the profit equation and reflect the short and long term profit possible through selection of superior genetics. For example, short term profit can be generated by a bull through the sale of his progeny, and the longer term profit generated by his daughters in a self-replacing cow herd.

Best Practice Guide to Animal Selection Using South African Simbra Selection Indexes

Incorporating selection index information into breeding decisions takes the hard work out of trying to decide how much emphasis you need to put on individual EBVs when determining which animals you want to retain in your herd or purchase. The recommended strategy for selecting animals is to complete the following steps:

  1. Identify the selection index of most relevance to your or your client’s breeding objectives. This decision should be aided by the index descriptions at the end of this document and the following flowchart.
  2. Rank animals on the chosen selection index. This can be done via the web search facility available for the breed.
  3. Consider the individual BREEDPLAN EBVs of importance. All breed level selection indexes are designed for the average of the production system specified in their description. This means that individual farm environments and management choices may require that their own thresholds are applied. For example, if looking for a bull to use over heifers, particular attention should be paid to Calving Ease and Birth Weight EBVs.
  4. Consider other traits of importance. Structure, fertility (e.g. BULLCHECKTM), temperament, genetic conditions and pedigree are all important additional considerations.

Further information is available in the A BREEDPLAN Guide to Animal Selection tip sheet that can be found in the Help Centre on the BREEDPLAN website.

Available South African Simbra Selection Indexes

The Simbra Cattle Breeders’ Society of South Africa currently reports three different selection indexes. These are the:

  • Self-Replacing Feedlot Index (SRF)
  • Self-Replacing Weaner Index (SRW)
  • Self-Replacing Grassfed Index (SRG)

Each selection index is reported in units of net profitability per cow mated (Rand), and targets the following specifications:

Self Replacing Feedlot Index (SRF)

  • Self-replacing commercial herd.
  • Selected heifers are retained for breeding, therefore maternal traits are important.
  • Progeny finished in a feedlot.
  • Steers target 510 kg live weight (275 kg HSCW) and heifers 420 kg (215 kg HSCW) at 15 months of age.
  • Emphasis on carcase quality.

Self-Replacing Weaner Index (SRW)

  • Self-replacing commercial herd.
  • Selected heifers are retained for breeding, therefore maternal traits are important.
  • Progeny sold at weaning to the feedlot sector.

Self-Replacing Grassfed Index (SRG)

  • Self-replacing commercial herd.
  • Selected heifers are retained for breeding, therefore maternal traits are important.
  • Progeny finished on pasture.
  • Steers target 500 kg live weight (260 kg HSCW) and heifers 430 kg (220 kg HSCW) at 23 months of age.
  • Emphasis on carcase quality.

 

More detail on the trait and EBV emphasis for each of the selection indexes described above is available in the South African Simbra Selection Indexes: Technical Specifications tip sheet that can be found in the Help Centre on the BREEDPLAN website.

If you have any further queries regarding the South African Simbra Selection Indexes, please do not hesitate to contact staff at the Simbra Cattle Breeders’ Society of South Africa.

Using South African Simbra Selection Indexes