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Interpreting South African Simmentaler Selection Indexes

There are currently two different selection indexes calculated for South African Simmentaler animals. These are:

  • Simmentaler Breeders Index
  • Simmentaler Profit Index

Each selection index describes a different production/market scenario and relates to a typical commercial herd using Simmentaler bulls. Producers are advised to use the selection index that most closely aligns to their production system. Both selection indexes are focussed on maternal traits and maintaining mature cow size for efficiency. In addition, each selection index targets the following specifications.

Simmentaler Breeders Index - Estimates the genetic differences between animals in net profitability per cow joined in an example self-replacing purebred Simmentaler herd. A portion of the heifers are retained for breeding and so maternal traits are of importance. This index assumes steers and surplus heifers will be finished in a feedlot for 160 to 180 days and weigh 480 to 555kg when marketed at 13 to 14 months of age.

Simmentaler Profit Index - Estimates the genetic differences between animals in net profitability per cow joined for an example crossbred self-replacing using Simmentaler bulls over Bos indicus content cross females. A portion of the heifers are retained for breeding and so maternal traits are of importance. This index assumes steers and surplus heifers will be finished in a feedlot for 140 to 160 days and weigh 420 to 490kg when marketed at 12 to 13 months of age.

All selection indexes are reported as an EBV, in units of net profit per cow mated (Rand) for a given production/market scenario. They reflect both the short term profit generated by a sire through the sale of his progeny, and the longer term profit generated by his daughters in a self-replacing cow herd (where applicable).

All selection index values have been derived using BreedObject technology. More detailed information regarding each selection index is provided in the downloadable document.