Indices

Indices have been created as an indicator of the profitability of an animals – in dollar terms – to assist those  that are less familiar with EBVs . Each index is ‘built’ differently to suit the particular focus the particular index is wanting to target

Angus New Zealand have 3 Indices:

• The Self Replacing (SRI).
• Ease of Calving (EOCI)
• Anguspure (API).
  
  

The Self Replacing Index

"The Angus Self-replacing Index" ranks bulls on their ability to generate profit (profit per cow mated) in a herd situation in which some females are retained for breeding and surplus females, along with all males, are slaughtered.
The main drivers of profit addressed by the Index include (in order of economic importance):

- Direct and Maternal Calving Ease
- Growth - Meat Yield
- Cow Survival
- Finishing Ability
- Fertility
- Cow Efficiency

In short, selection on the Index is expected to favour production of a cowherd with excellent reproductive efficiency, rearing progeny with moderate-to-high growth rates and high yielding carcasses.

Comparing the lifetime profitability of two bulls

The following example illustrates how potential differences in lifetime profitability can be approximated between bulls with different Indexes. These estimates of value differences may be conservative.
Two bulls with Self-replacing Indexes of $40 and $20 are mated to genetically similar cows. If each bull mates 200 cows during its lifetime, the first bull will generate $2000 ($(40-20)/2 x 200) more profit during its lifetime than the second bull (the $20 profit advantage must be divided by 2 because a bull only passes half his genes on to each of his progeny).

Figure 1. The Self Replacing Index

Figure 2. Self Replacing Index Trend Graph

 Figure 3. Ease of Calving

 Figure 4. Ease of Calving Trend Graph

AngusPure Index

The production system described and modelled for this index is the same as for the Self Replacing index (i.e. what the top financial 10% of commercial beef cow farmers are achieving) but will tend to highlight higher marbling sires with progeny turn-off at around 16-20 months of age.
Below is the EBV emphasis of the new index.

 Figure 5. AngusPure Index Graph

Figure 6. AngusPure Index Trend Graph