Page 9 - Nethertown Angus Catalogue ebook

retail yield percentage in a standard 400 kg carcase. Sires with larger EBVs
are expected to produce progeny with higher yielding carcases.
Intramuscular Fat EBV (%) is an estimate of the genetic difference in the
percentage of intramuscular fat at the 12/13th rib site in a 400 kg carcase.
Depending on market targets, larger more positive values are generally
more favourable.
Docility EBV (%) is an estimate of the genetic differences between animals in
temperament. Docility EBVs are expressed as differences in the percentage
of progeny that will be scored with acceptable temperament (ie. either
“docile” or “restless”).
Accuracy
Accuracy (%) is based on the amount of performance information available
on the animal and its close relatives - particularly the number of progeny
analysed. Accuracy is also based on the heritability of the trait and the
genetic correlations with other recorded traits. Hence accuracy indicates the
“confidence level” of the EBV. The higher the accuracy value the lower the
likelihood of change in the animal’s EBV as more information is analysed for
that animal or its relatives. Even though an EBV with a low accuracy may
change in the future, it is still the best estimate of an animal’s genetic merit
for that trait. As more information becomes available, an EBV is just as likely
to increase in value, as it is to decrease.

Selection Indexes
There are currently two different selection indexes calculated for New
Zealand Angus animals. These are Self-Replacing and AngusPure. Each
selection index describes a different production/market scenario and relates
to a typical commercial herd in New Zealand that is targeting the following
specifications.
Index values are reported as EBVs, in units of relative earning capacity ($’s)
for a given market. They reflect both the short-term profit generated by a
sire through the sale of his progeny, and the longer-term profit generated by
his daughters in a self-replacing cow herd. More information is available on
selecting animals using a selection index.
The Index values are derived using BreedObject technology.
More information is available from the BreedObject web site.
Self-Replacing Index ($) - Estimates genetic differences between animals
in net profitability per cow joined for a self-replacing commercial herd,
targeting the production of grass finished steers. Steers are assumed
marketed at 525 kg live weight (280 kg carcase weight and 10 mm fat depth)
at 16 months of age.
AngusPure Index ($) – Estimates genetic differences between animals
in net profitability per cow joined for a self-replacing commercial Angus
herd, targeting the production of grass finished steers for the AngusPure
programme. Steers are assumed marketed at 525 kg live weight (280 kg
carcase weight and 10 mm fat depth) at 18 months of age with a significant
premium paid for marbling.
Heifer/Dairy Terminal Index ($) – 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 carcase weight and 7 mm fat depth) at approximately
24 months of age.
Note that $Index values for individual animals are sensitive to the
assumptions used in the BreedObject analysis to calculate the selection
index. More information is available on the weightings used in the New
Zealand Angus Selection Indices.
Nethertown Angus 7