Page 17 - Hingaia Angus Sale Catalogue ebook

INDEX DESCRIPTIONS Angus Pure Index (API)

New Zealand Angus AngusPure Index - Predicted Response
The following three graphs reflects the relative change if the New Zealand Angus Published Sires (at the Mid-August
2020 TransTasman Angus Cattle Evaluation) were ranked on this selection index and the top 10% were used within a
Expected Change in Individual Traits
breeding program. Given that the Published Sires are the sires of the next generation(s) of New Zealand Angus cattle
and have more highly accurate EBVs (due to having progeny) than the average animal in the database, these graphs
represent the approximate selection response one would expect to see in the breed from using this index.

Self Replacing Index (SRI)

New Zealand Angus Self-Replacing Index - Predicted Response GL SS DC

Expected Change in Individual Traits Genetic Selection of bulls using only the API tool will on average over time develop a cow herd with the following:
Rib
Rump
RBY
200W
IMF
600W
400W
MCW
CEd
Milk
Cwt
CEm
BW
EMA
Above the 0 line (X axis) selects for more positive numbers and below the line selects for more negative numbers.
For some traits (e.g. growth), a positive response is desirable and for others (e.g. days to calving), a negative response is desirable.
•
A slowly increasing cow weight/size, and milk production
• Improved weaning rate through increased fertility and easier calving
CEd CEm GL BW 200W 400W 600W MCW Milk SS DC Cwt EMA Rib Rump RBY IMF • Progeny will be prime at heavy carcase weights where the improved marbling and subsequent eating quality traits
can be expressed.

Above the 0 line (X axis) selects for more positive numbers and below the line selects for more negative numbers.
For some traits (e.g. growth), a positive response is desirable and for others (e.g. days to calving), a negative response is desirable. These characteristics are ideal for an environment where the cow herd can be managed with extra feed if seasonal feed
deficits occur.
Genetic Selection of bulls using only the SRI tool will on average over time develop a cow herd with the following:
Checking individual EBVs relevant to your herd is advised.
• Improved weaning rate through increased fertility and easier calving
• A slowly decreasing cow size, milk and slowly increasing body condition
• Progeny will be prime at a younger age for slaughter Comparison of SRI and API
SRI is a maternal trait emphasised index. API is also a maternal driven index with added carcase trait emphasis.
These characteristics are ideal for an environment where the herd is exposed to prolonged seasonal feed deficits
and feeding supplement is unlikely. API selected animals can produce more net profit per animal through extra performance when feed is abundant.
Finished progeny can be taken to heavier weights with increased likelihood of achieving marbling premiums.
Checking individual EBV’s relevant to your herd is advised.
SRI selected animals can produce more net profit per animal through extra performance in environments where
the cow herd is likely to be challenged by regular seasonal feed deficits, maintaining body condition is critical
to longevity and feeding out is not a viable option.

Checking individual bull EBVs to make sure the index and the EBVs match your expectations are advised.
Using the flow chart may help you with your decisions.

Hingaia Angus Bull Sale 2021 17