Page 11 - Woodbank Matariki 2021 Catalogue ebook

INDEXES EXPLAINED

NEW ZEALAND ANGUS SELECTION INDEXES

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.

Checking individual EBV’s relevant to your herd is advised.

Woodbank Angus & Matariki Herefords Bull Sale 2021 9