More detailed information regarding each selection index is provided in the downloadable document.

The New Zealand Angus Association currently reports three different selection indexes. These are the:

• Self Replacing Index
• AngusPure Index
• Heifer/Dairy Terminal Index

All of the selection indexes described above have been derived using BreedObject software. The BreedObject selection index development process involves four major steps. These steps are:

1. A detailed description of the input costs and value generation of the commercial herd and target production system.
2. Once the target production system is described, the BreedObject software evaluates how each trait influences profitability and the economic value of improving each trait.
3. The BreedObject software then assesses what emphasis needs to be applied to each Estimated Breeding Value (EBV) trait to achieve the maximum profitability in the production system and for the market end point for which that index was designed. This step includes evaluating the selection response expected from direct selection on the individual EBVs and the correlated responses expected from selection on related EBVs.
4. The importance placed on each EBV results in the selection index value that is calculated for each animal.

Each selection index describes a different production system/market scenario and relates to a typical commercial herd using Angus bulls. As is the case for EBVs, each selection index can be used to rank and compare animals on their genetic merit. Producers are advised to use the selection index that most closely aligns to their production system. See the Using New Zealand Angus Selection Indexes tip sheet, available in the Help Centre on the BREEDPLAN website, for further information on the identification and utilisation of the most applicable selection index for your herd.

All selection indexes are reported in units of net profitability per cow mated ($) for the production system/market scenario they describe. Selection indexes account for both sides of the profit equation (costs as well as income), and also reflect the relative short and long term profit associated with possible selection decisions. 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.

Each of the selection indexes are focused on efficient beef production while also targeting the following specifications:

Self Replacing Index (SRI) - Estimates the genetic differences between animals in net profitability per cow joined in an example self-replacing commercial herd that targets the production of grass finished steers. Steers are assumed marketed at approximately 480 kg live weight (265 kg carcase weight and 7 mm fat depth) at approximately 16 months of age. Selected heifers are retained for breeding and the balance marketed at approximately 16 months weighing 415 kg (230 kg carcase weight and 8 mm fat depth). As some daughters are retained, maternal traits are also of importance.

AngusPure Index (API) - Estimates the genetic differences between animals in net profitability per cow joined in an example self-replacing commercial Angus herd that targets the production of grass finished steers for the AngusPure programme. Steers are assumed marketed at approximately 530 kg live weight (290 kg carcase weight and 10 mm fat depth) at approximately 20 months of age. Selected heifers are retained for breeding and the balance marketed at approximately 20 months weighing 450 kg (240 kg carcase weight and 10 mm fat depth). A significant premium for carcase quality was assumed and, as some daughters are retained, maternal traits are also of importance.

Heifer/Dairy Terminal Index (HDT) - Estimates the genetic differences between animals in net profitability per female joined in an example herd where all progeny are marketed.  All progeny are marketed at approximately 510 kg live weight (280 kg carcase weight and 7 mm fat depth) at approximately 24 months of age.

More detailed information regarding each selection index is provided in the downloadable document.

If you have any further queries regarding the New Zealand Angus Selection Indexes, please do not hesitate to contact staff at the New Zealand Angus Association.