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 the New Zealand Murray Grey Selection Index
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:
- 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.
- Rank animals on the chosen selection index. This can be done via the web search facility available for the breed.
- 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.
- Consider other traits of importance. Structure, fertility (e.g. BULLCHECKTM), temperament, genetic conditions and pedigree are all important additional considerations.
Available New Zealand Murray Grey Selection Indexes
The New Zealand Murray Grey Beef Cattle Society Inc. currently reports one selection index.
This is the:
- Dairy Index
Each selection index is reported in units of net profitability per cow mated ($), and targets the following specifications:
- Commercial dairy herd targeting the production of dairy beef progeny.
- Large emphasis on calving ease to suit bulls used over dairy cows.
- All progeny (including heifers) are slaughtered.
- Steers are assumed marketed at 450 kg live weight (240 kg HSCW & 6 mm P8 fat depth) at 16 months of age.
Please note: The Dairy Index is used for the selection of Murray Grey bulls to produce dairy beef. It is not suitable for use when selecting bulls for a self-replacing purebred Murray Grey breeding program.
More detail on the trait and EBV emphasis for the selection index described above is available in the New Zealand Murray Grey Selection Index: Technical Specifications tip sheet that can be found in the Help Centre on the BREEDPLAN website.
If you have any further queries regarding the New Zealand Murray Grey Selection Index, please do not hesitate to contact staff at the New Zealand Murray Grey Beef Cattle Society.