Page 4 - C-B Charolais Bull and Heifer Production Sale – March 23, 2021

Terminal Sire Index

The AICA Terminal Sire Index (TSI) utilizes economic
and management descriptions of your ranching
operation, along with EPD on available Charolais bulls
to assist in identifying the most profi table sires for
your unique operation. Using economic selection index
theory, this tool will generate dollar indexes per terminal
progeny produced on bulls in the AICA database, ranking
them for profi t potential given the inputs you provide.
The dollar indexes are to be interpreted much like single
trait EPD. For example, if sire A’s index is $191.66 and
sire B’s index is $200.00, then we would expect Sire B’s
offspring to average $8.34 more net return ($200.00 -
$191.66) than sire A’s offspring.
This program assumes all offspring are marketed
based upon carcass value and replacement females are
purchased or raised as a separate enterprise. Inputs
should be provided based on historical information from
your operation. The TSI economic default value is based
on a three year rolling averaged utilizing USDA data.

It is important to remember that this is a Terminal Sire
Index and should not be used as the sole selection tool
for producing replacement females. Producers should
consider the appropriate traits for the selection of sires
to produce replacement females.

INTRODUCTION
In an ideal selection scheme producers would select
breeding animals that excel in all traits. In reality
though, this is not the case. Producers often fi nd
it necessary to make compromises in selection
to balance the strengths and weaknesses among
selection candidates. This is driven by the fact
that unfavorable relationships exist between traits.
Therefore, it is diffi cult for producers to weigh
all the options appropriately given the various
management programs and diversity among beef
cattle. To make this decision even more challenging
is the fact that not all producers sell beef cattle
based on the same marketing grid.
A selection index is a formal method of combining
Expected Progeny Differences (EPD) for different
traits into one single value on which to base
selection decisions. The AICA Terminal Sire Index
uses estimates of the genetic relationships between
traits and breeder historical input data on the cow
herd a sire is to be mated along with marketing and
carcass grid specifi cations to determine economic

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