Page 10 - Ariki ebook

INDEX DESCRIPTIONS

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 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

Expected Change in Individual Traits

CEd CEm GL BW 200W 400W 600W MCW Milk SS DC Cwt EMA Rib Rump RBY IMF
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.
Genetic Selection of bulls using only the SRI tool will on
average over time develop a cow herd with the following:
• 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
These characteristics are ideal for an environment where the herd
is exposed to prolonged seasonal feed deficits and feeding
supplement is unlikely.

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