Page 12 - Brackenfield Angus Catalogue ebook

INDEX DESCRIPTIONS AngusPure Index (API)
The following three graphs reflects the relative change if the
New Zealand Angus Published Sires (at the Mid-August 2020 New Zealand Angus AngusPure Index - Predicted Response
TransTasman Angus Cattle Evaluation) were ranked on this
selection index and the top 10% were used within a 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 Expected Change in Individual Traits
selection response one would expect to see in the breed from
using this index.

Self Replacing Index (SRI)
CEd CEm GL BW 200W 400W 600W MCW Milk SS DC Cwt EMA Rib Rump RBY IMF
New Zealand Angus Self-Replacing Index - Predicted Response
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),
Expected Change in Individual Traits Genetic Selection of bulls using only the API tool will on
a positive response is desirable and for others (e.g. days to calving),
a negative response is desirable.

average over time develop a cow herd with the following:
• Improved weaning rate through increased fertility
and easier calving
• A slowly increasing cow weight/size, and milk production
• Progeny will be prime at heavy carcase weights where the
CEd CEm GL BW 200W 400W 600W MCW Milk SS DC Cwt EMA Rib Rump RBY IMF improved marbling and subsequent eating quality traits
can be expressed.
Above the 0 line (X axis) selects for more positive numbers and below These characteristics are ideal for an environment where
the line selects for more negative numbers. For some traits (e.g. growth), the cow herd can be managed with extra feed if seasonal feed
a positive response is desirable and for others (e.g. days to calving),
a negative response is desirable. deficits occur.
Genetic Selection of bulls using only the SRI tool will on Comparison of SRI and API
average over time develop a cow herd with the following:
SRI is a maternal trait emphasised index. API is also a maternal
• Improved weaning rate through increased fertility driven index with added carcase trait emphasis.
and easier calving
• A slowly decreasing cow size, milk and slowly increasing API selected animals can produce more net profit per animal
body condition through extra performance when feed is abundant.
Finished progeny can be taken to heavier weights with increased
• Progeny will be prime at a younger age for slaughter
likelihood of achieving marbling premiums.
These characteristics are ideal for an environment where the herd SRI selected animals can produce more net profit per animal
is exposed to prolonged seasonal feed deficits and feeding through extra performance in environments where
supplement is unlikely. 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.
12 BRACKENFIELD