Megan Rolf, Bio
genomic-enhanced EPD
are returned to IBBA, that information is added to the suite
of information utilized in genetic prediction during the next
National Cattle Evaluation. The next time the EPDs are released,
that animal will have a GE-‐EPD along with a corresponding
increase in accuracy (in addition to accuracy gained from other
sources of information, such as reporting yearling weights or
other performance data).
What are the benefits of genomic testing
for sire selection?
EPDs are estimates that can change over time as more
information gets added to the evaluation, which is why
reporting high-‐quality performance data within appropriately-‐
assigned contemporary groups is so critical. When more
information gets added, the accuracy increases. The higher
the accuracy, the less that EPD is likely to change over time
and the more confidence we have in that estimate. Genomic
testing essentially provides an accuracy jump-‐start before a
sire has large numbers of progeny records to contribute to
an evaluation. Practically speaking, this allows producers
to screen herd sires with increased confidence due to that
increased accuracy. For example, if a producer endeavors to
select a yearling herd sire for breeding to heifers, increased
accuracy will result in more confidence in purchasing a calving
ease sire. Genomic information can also be extremely useful in
shortening the timetable for gaining accuracy for sex-‐limited
traits such as milk production, where the first records on a sire
won’t arrive until after his first daughters calve. When keeping
replacement heifers, a bull can have enormous influence on the
cowherd, and the increased accuracy gained from GE-‐EPDs
can be helpful in selecting the right herd sire to meet your
long-‐term breeding objectives.
What are the benefits of genomic testing
for replacement heifer selection?
Much of the focus on genetic selection is placed on choosing
the right herd sire, because the sire has such a heavy influence
on the calf crop. However, it is important to remember that
the females in the herd contribute the other half of the genetic
background of those calves. For this reason, it can pay to
place emphasis on choosing quality replacement females. One
disadvantage in females is their lack of prolificacy compared
to bulls, which can sometimes limit the accuracy gains in
their productive lifetime. For this reason, genomic testing
can sometimes provide a greater increase in accuracy for a
heifer than all of the individual performance records for her
progeny in her lifetime, so it is worth considering testing your
replacement candidates. One additional benefit of genomic
testing that is often forgotten is that the accuracy gains are
equivalent regardless of sex, which can do a lot to level the
accuracy playing field early in an animal’s lifetime.
The release of GE-‐EPDs provides Brangus breeders with
another tool in their selection arsenals.
Use of genomic tools for selection provides a variety of benefits
that producers can capitalize upon. Increases in accuracy
of EPDs can not only provide additional information when
purchasing bulls and females, but can also be utilized effectively
for within-‐herd selection and culling decisions.
Megan Rolf, Ph.D. joined the faculty of the Department of Animal Sciences
at Oklahoma State University in June of 2012 as Assistant Professor of Beef Cattle
Management and State Beef Cattle Extension Specialist. Her extension goals include
increasing awareness and understanding of genetic and genomic selection tools within the
beef industry.
Megan was raised on a small cow-calf operation in east central Kansas near LeRoy.
She earned her B.S. in Animal Sciences with a science option at Kansas State University
in 2005. Megan relocated to Columbia, Mo. to pursue a M.S. in Animal Science at the
University of Missouri, with a focus on use of SNP data to generate genomic relationship
matrices. After completion of her M.S., she completed a Ph.D. in Genetics at MU, with
a research focus on the exploration of methods to partition training and validation
populations for improving across-breed genomic selection for carcass traits.
