UNDERSTANDING AND USING
ECONOMIC SELECTION INDEXES
By Dr. Art Linton, Extension Beef Scientist
Washington State University - Prosser
The concept of Expected Progeny Differences (EPDs) was introduced about 25
years ago with the publication of the first breed national sire summaries. The first sire
summaries included EPDs for five traits. Since that time the number of EPDs available
for each animal has increased to as many as 19, depending upon the breed. While this
wide array of EPDs helps describe the genetic merit of individuals, they also greatly
complicate selection decisions for purebred breeders and commercial producers alike.
The use of multi-trait selection indexes as tools for commercial beef producers
and seedstock breeders is rapidly evolving in the beef industry. Selection indexes are a
tool to select for several traits at once. An index approach takes into account genetic and
economic values to select for economic merit. A multi-trait index approach can be
contrasted to single trait selection or independent culling levels. An index is challenging
to develop, but the end result is easy to use, adding simplicity and convenience to a multitrait approach.
Selection indexes combine information from an animal’s EPDs into just a few
numbers that reflect their relative economic value. Economic selection indexes assist
producers to compare and select animals with the most favorable combination of EPDs to
maximize profit in a given production situation. In the calculation of the economic
selection indexes EPDs are weighted based upon their economic importance to a
particular production scenario. Determinations of the economic weighting factors are
based upon the average cost of various production inputs and the value of various
products over a period of time to avoid normal short term price fluctuations.
Economic selection index values are expressed in dollar values. For example, the
American Simmental Association’s indexes calculate the estimated differences between
bulls in net dollars returned per cow exposed. Thus, a bull with an index value of +$23
would be expected to return $10 more per cow exposed than a bull with a +$13 index
when used on the same set of cows (+$23 - +$13 = $10 ). It is important to remember that
these index values (like EPDs) are for comparison purposes only, and the absolute
numbers are of little meaning. As is the case with EPDs, economic index values should
be used only on a within-breed basis.
Commercial producers can also use indexes to determine how much a bull is
worth. For example, if we refer to the two bulls in the previous paragraph and expect the
bulls to be used on 30 cows each per year over four years, their value difference is
$1,200. That is obtained by multiplying the $10 per cow index difference times 30 cows
per bull per year times four years.
A brief explanation of the indexes available for the various breeds follows.
See the respective breed web site or published sire summary for more information.
Angus
 Weaned Calf $Value ($W) quantifies value differences of sires when used in the
production and sale of weaned calves with the normal retention of replacement
heifers.
 Feedlot Value ($F) accounts for feedlot performance with a formula that includes
industry values for days on feed, ration costs, and cash cattle prices.
 Carcass Grid Value ($G) combines quality grade and yield grade attributes
calculated on a three year rolling average of industry grids.
 Total Beef Value ($B) reflects the value differences in the feedlot and on the rail.
It incorporates $F and $B, but is not a sum of the two
 Cow Energy Value ($EN) assesses differences in dollar savings related to cow
maintenance and lactation costs. A larger value is more favorable.
Herefords
 Baldy Maker Index ($BMI) is an index to maximize profit using Hereford bulls
in a rotational crossbreeding program with retention of ownership through the
feedlot and fed cattle marketed on the Certified Hereford Beef pricing grid.
 Calving Ease Index ($CEZ) is similar to BMI$ except that bulls are mated only
to yearling heifers. This index increases emphasis on direct and maternal calving
ease.
 Certified Hereford Beef Index ($CHB) is a terminal sire index with all offspring
sold out of a feedlot on a CHB pricing grid.
Simmental
 All Purpose Index (API) evaluates sires being used on the entire cowherd (both
Angus first-calf heifers and mature cows) with a proportion of the heifer calves
retained for breeding and the steers and remaining heifers fed out and sold on a
grid.
 Terminal Index (TI) is designed for evaluating sires in situations where they are
bred to mature Angus cows, all offspring are fed out and sold on a grid.
 Heifer-Sire Index (HI) is appropriate for sires to be used on first-calf heifers
where a portion of the daughters are retained as replacements and the balance of
their get are fed for slaughter.
Charolais
 Terminal Sire Profitability Index assumes all offspring are marketed based
upon carcass value and replacement females are purchased or raised as a separate
enterprise.
Other Breeds
It is likely that other breeds will soon be developing their own economic selection
indexes.
04/07/2005