Page 16 - TwinOaks Angus 2021 Catalogue eBook

INDEXES

There are currently three different selection indexes calculated for New Zealand Angus animals. These are:

• SELF REPLACING INDEX • ANGUSPURE INDEX • HEIFER/DAIRY TERMINAL INDEX
Each selection index describes a different production/market scenario and relates to a typical commercial herd using Angus bulls.
Producers are advised to use the selection index that most closely aligns to their production system. Each selection indexes is
focused on efficient beef production, including maternal traits where appropriate. In addition, each selection index targets the
following specifications.
SELF REPLACING INDEX (SRI) - Estimates the genetic differences between animals in net profitability per cow joined in an example
self-replacing commercial herd that targets the production of grass finished steers. Steers are assumed marketed at approximately
480 kg live weight (265 kg carcass weight and 7 mm fat depth) at approximately 16 months of age. Selected heifers are retained for
breeding and the balance marketed at approximately 16 months weighing 415 kg (230 kg carcass weight and 8 mm fat depth). As
some daughters are retained, maternal traits are also of importance.
ANGUSPURE INDEX (API) - Estimates the genetic differences between animals in net profitability per cow joined in an example self-
replacing commercial Angus herd that targets the production of grass finished steers for the AngusPure programme. Steers are
assumed marketed at approximately 530 kg live weight (290 kg carcass weight and 10 mm fat depth) at approximately 20 months
of age. Selected heifers are retained for breeding and the balance marketed at approximately 20 months weighing 450 kg (240 kg
carcass weight and 10 mm fat depth). A significant premium for carcass quality was assumed and, as some daughters are retained,
maternal traits are also of importance.
HEIFER/DAIRY TERMINAL INDEX (HDT) - Estimates the genetic differences between animals in net profitability per female joined in an
example herd where all progeny are marketed. All progeny are marketed at approximately 510 kg live weight (280 kg carcass weight
and 7 mm fat depth) at approximately 24 months of age.
All selection indexes are reported as an EBV, in units of net profit per cow mated ($) for a given production/market scenario. They
reflect both the short term profit generated by a sire through the sale of his progeny, and the longer term profit generated by his
daughters in a self-replacing cow herd (where applicable).
If You have any further questions regarding NZ Angus Selection Index’s, please contact us at Twin Oaks we are happy to discuss
index’s and EBV’s and how to make use of them in your breeding programme.

TWIN OAKS HERD COMPARED TO NZ ANGUS AVERAGE

TWIN OAKS SALE BULLS 180
COMPARED TO NZ BREED 160
AVERAGE 140

120
TWIN OAKS SALE BULLS 100
NZ ANGUS AVERAGE 80
60

40
20
0
SRI API HDT