Page 19 - Aug242023

profitability, then the Termi- Do the inputs for $API The Midwest Cattleman · August 24, 2023 · P19
nal Index ($TI) is what you and $TI change over time,
should use. The $TI was de- or does the formula stay each with their own accuracy. netic merit in a range of other
If comparing a highly proven traits. This means that if a
signed for breeding systems the same?
with the assumption that all The economic inputs for sire to that of a yearling bull, sire is exceptional for only one
the reliability of the young- of the key traits in an index
females were purchased or $API and $TI largely stay
developed separately. A ter- the same across years. They er bull’s index is inevitably and poor for the others, he
may appear more favorable
lower.
minal mating system places are designed to be robust in
Also, it’s extremely im- than bulls with average per-
greater emphasis on carcass market fluctuations and not portant to remember that an formance across all traits.
performance, growth, and di- inappropriately discount an
rect calving ease. animal’s genetic worth if corn index allows superiority in
one trait to outweigh poor ge-
It’s important to note that prices rose suddenly and then
all seedstock breeding pro- dropped back to normal a few
grams are different and have months later. Since breed-
commercial customers with ing decisions happen at a All-Purpose Index ($API): Dollars per cow exposed under
varying goals, so the best sug- fixed point in time, you want an all-purpose-sire scenario.
gestion would be to use the an index that can withstand
$API and $TI as a starting those market fluctuations. Terminal Index ($TI): Evaluates sires for use on mature
point and then focus on other Angus cows with all offspring put on feed and sold grade and
traits to develop a breeding How long can it take yield.
program. for a producer to see a
measurable change after
Since each producer’s committing to using Interpreting $API and $TI: Just as with EPD, zero in on
operation is unique, how indices in selection the unit difference between bulls. (As described above, index
can we trust that an index decisions? units are in dollars per cow exposed.) The difference can
will do what it’s supposed Unlike single trait selec- be used to determine how much a bull is worth compared
to? tion, realizing the genetic to another. Put another way, how much you can pay for one
Indices are designed to progress from economic-in- bull compared to another. For example, when buying an all-
be robust in their function. dex-based selection will inev-
And while every operation is itably be slower. Since $API purpose-type sire, you can quickly figure a bull scoring +100
unique, the beef industry’s uses a balanced approach to for $API is worth an extra $6,000 over a +50 bull if both are
profit centers are fairly con- weighting every economically exposed to 30 cows over 4 years ($50 diff. x 30 hd. x 4 yr.=
stant across all regions. The relevant trait, you will not be $6,000). Percentile is required to determine where a bull’s
commercial industry needs using the extreme outliers for index value ranks him relative to other bulls in the breed.
females that stay in the herd a single trait. For traits with
until profitable, don’t exceed low heritability, this notice-
reasonable nutrition require- able difference will be even
ments, produce and wean a slower. This process can take
heavy calf that is born healthy, years with long generation in-
grows well, and kills with ex- tervals, and the need to keep
cellent terminal merit. This is females around until profit-
obviously a simplification of able.
the nuances of the beef indus-
try, but overall this is what an Do you have any tips for
$API index is designed to ac- producers wanting to
complish. And while breeders utilize $API or $TI?
can tailor their breeding pro- One thing that is important
grams to fill niches, an index to note about indices is the re-
will guide a breeding program liability of the prediction. We
in the direction of commercial do not calculate an “accura-
profitability. cy” for indices since they are
aggregated from many EPD,

Dr. Ken Odde runs commercial cattle in South Dakota
and is the past department head for the Animal
Sciences and Industry Department at Kansas State
University. He shares his insight on utilizing $API and
$TI.

“The purpose of a selection index is to help the
commercial producer, or the potential buyer, in
appropriately balancing traits. We now have EPD on such
a wide variety of traits that it is difficult to decide what
is actually the most important. Indices are really a breed
association effort to help producers with appropriately
balancing traits.”