Page 9 - Storth Oaks Angus Catalogue ebook

Indexes have changed.......
These developments have changed how EBV’s are valued in selection indexes. In particular, the
enhanced modelling of cow weight increases the impact that total cow feed costs (i.e. length of
feeding + feed price + feed quality) have on the profitability of the represented production systems.
This means that the new software can construct indexes that can be tailored to the different pro-
duction environments that are found across New Zealand where variation in cow feed costs exist.
Each selection index describes a different production/market scenario and relates to a typical com-
mercial herd using Angus bulls. Producers are advised to use the selection index that most closely
aligns to their production system. Each selection indexes is focussed 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 car-
case 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
carcase 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 ap-
proximately 530 kg live weight (290 kg carcase weight and 10 mm fat depth) at approximately 20
months of age. Selected heifers are retained for breeding and the balance marketed at approxi-
mately 20 months weighing 450 kg (240 kg carcase weight and 10 mm fat depth). A significant
premium for carcase quality was assumed and, as some daughters are retained, maternal traits
are also of importance.

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).