The Santa Gertrudis Breeders’ (Australia) Association currently reports three different selection indexes. These are the:

• Breeding Production Index
• Fertility Plus Index
• 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 Santa Gertrudis 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 Australian Santa Gertrudis 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 selection index also considers the entire beef production chain whether animals are bred, grown and finished in one operation or sold as young cattle to backgrounders and/or feedlots for finishing.  

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

Breeding Production Index - Estimates the genetic differences between animals in net profitability per cow joined for a typical self-replacing commercial herd in productive country with good management.  Selected heifers are retained for breeding and so maternal traits are of importance. Heavy export markets are the target for all turn-off animals at weights above 520 kg (260 kg HSCW & 10-15 mm P8 fat) at 22-30 months of age.  Given this is a breeding index for herds where seasonal conditions, country type and herd management are less likely to adversely affect herd productivity, a balance of growth, carcase and fertility traits is adopted.

Fertility Plus Index - Estimates the genetic differences between animals in net profitability per cow joined for a typical self-replacing commercial herd in less productive country and/or the herd is run under lower management intensity. Selected heifers are retained for breeding and so maternal traits are of importance.  Heavy export markets are the target for all turn-off animals at weights above 520 kg (260 kg HSCW & 10-15mm P8 fat) at 22-30 months of age. Given this is a breeding index for herds where seasonal conditions, country type and/or herd management may regularly adversely affect herd productivity, fertility, growth and carcase traits are considered with fertility being the trait of most influence.

Terminal Index - Estimates the genetic differences between animals in net profitability per female joined in a typical commercial herd where all progeny are marketed. Heavy export markets are the target at weights above 520 kg (260 kg HSCW & 10-15 mm P8 fat) at 22-30 months of age. Given this is a terminal index, growth and carcase traits are the focus, along with calving ease which helps ensure live calves are born. Fertility traits are not considered.

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

If you have any further queries regarding the Australian Santa Gertrudis Selection Indexes, please do not hesitate to contact staff at your BREEDPLAN processing centre.

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