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Utilizing Genetics in the Bull Selection Process
March, 2022
Kalan
Royal, UF/IFAS Extension Highlands County, Sebring
Cattle producers must make many important management
decisions throughout the year, such as selecting a herd sire. Bulls are
responsible for the largest proportion of calf crop genetics each year.
Purchasing bulls based on phenotype is still a common practice; however,
utilizing Expected Progeny Differences (EPDs) during the selection process
can help producers meet the goals of their operation by offering a guide to
the genetic potential of a bull. The impact a bull can have on an operation
is profound, therefore value should be placed in understanding evaluation
tools that are available to use in the selection process.
When buying a bull, the objective of the cattle
producer should be to purchase an animal that is going to improve the
genetics of his offspring. Selecting bulls based solely on physical
appearance or raw phenotypes (actual weights) fails to factor in
environmental influences while overlooking the genetic potential of a bull.
Environmental influences such as feed and forage availability and herd
management do not get passed on to the bull’s offspring. The addition of
EPDs in the selection process can quantify genetic differences that will be
passed down to the calf crop.
Expected Progeny Differences (EPDs) provide an
estimate of the transmitting ability of a parent to its offspring. EPDs
allow producers to predict how future progeny of a sire are expected to
perform compared to the progeny of other sires within a breed regardless of
age or location of the animal(s). Purebred cattle producers provide data and
information to their respective breed associations that is used to calculate
EPDs. Data submitted from the actual performance of an animal, an animal’s
progeny performance, the performance of indirect relatives (brothers and
sisters) and information from an animal’s ancestry are used when calculating
EPDs. The genetic makeup of an animal will never change but the amount of
information we know can change, therefore the more data gathered on a bull
the greater the accuracy of EPDs becomes. Accuracy (ACC) is improved as data
is submitted providing bull buyers with an increased level of confidence for
the genetic merit of a sire by reflecting the precision of specific EPD
traits. Accuracy will be displayed under EPDs on the chart and are displayed
on a scale of 0 – 1.
Carcass, maternal and performance traits are all
measured by EPDs. When looking at EPDs single trait selection is dangerous
and can have negative consequences. Selection for extremes in any direction
for any given trait can change affect reproduction efficiency. Traits should
be selected based off economic importance to the operation that align with
the goals of the operation.
Cattle operations that are marketing or retaining
replacement heifers will more than likely focus on maternal traits such as
Calving Ease Maternal (CEM), Heifer Pregnancy (HP) and Stayability (Stay)
along with Birth Weight (BW) and Calving Ease (CE). Producers that retain
ownership of cattle through the feedlot will probably add value to Carcass
Weight (CW), Marbling (Marb), Yield Grade (YG) and Ribeye Area (REA) during
selection along with Birth Weight (BW) and Weaning Weight (WW).
Breed associations display this
information differently, so it is recommended to find an EPD guide specific
to the breed.
Breed associations have also began adding selection
indices which were designed to match production goals of an operation. A
selection index will include a set of traits that have been determined as
having production importance. Research is done by the breed associations to
understand which individual traits should be included in the index. Examples
of selection indices would be Fertility Index (FI) and Terminal Index (TI)
indices that the International Brangus Breeders Association provides or the
Terminal Sire Index (TSI) the American International Charolais Association
provides. The utilization of a selection index when comparing potential herd
sires gives producers the ability to evaluate a single number that has
combined several traits of value to meet a focused goal rather than
individual comparison of traditional EPDs.
Genomic-enhanced EPDs (GE-EPDs) utilize DNA
information collected from bulls to provide an increased reliability of
EPDs. GE-EPDs improve accuracy of EPDs, especially in young bulls who have
no progeny. Genomics can provide information to reflect the equivalent of
around 10 progeny records, depending on the trait, for a young bull.
It is important to remember that EPDs allow for
comparisons of bulls within the same breed. This information is displayed as
a number so buyers should understand how to read these numbers and what the
breed averages are. Below the EPDs there are typically two additional rows
of information. The first is Accuracy (ACC) which increases by data
submitted on the progeny of an animal or DNA testing and the second being %
Rank which allows producers to compare bulls within the breed. The U.S. Meat
Animal Research Center publishes an Across-Breed EPD (ABEPD) table yearly
providing adjustment factors to create a common EPD scale that can be used
to evaluate bulls of different breeds.
Expected Progeny Differences (EPDs) are a valuable
tool that cattle producers both commercial and purebred, should take
advantage of when making their next bull selection. EPDs allow producers an
insight on the genetic potential an animal can pass on to his offspring.
Setting clear goals for the operation will influence the traits that are of
importance for the producer to meet their production goals. Cattle
performance is influenced by the environment and genetics. Regardless of how
good the EPDs are, bulls must be structurally sound and pass breeding
soundness exam as reproduction is the goal of purchasing bulls. Utilizing
every tool available in the selection process gives producers the ability to
meet the goals of the operation and buy bulls with an added confidence of
what they are getting.