Performance Line
Release Notes for Single-Step EPDs
powered by BOLT
By Tonya Amen, National Center for Beef Excellence
By the time this issue reaches you, NALF will have
released Single-Step EPDs powered by BOLT.
Key changes impacting all IGS-run traits are
highlighted below. Going forward, these traits will
be updated weekly. Please note that Gest and SC
will continue to be run at Colorado State 2-3 times
per year and are exempt from these comments.
For all IGS traits, two major changes are
reflected in the new BOLT-derived EPDs.
1)
Single-Step Incorporation of Genomics –
Formerly, results from genomic tests were
blended with an animal’s EPD after the
bi-annual evaluation was complete. This
method required frequent upkeep in the way
of periodic recalibration and results only
impacted the animal tested, not its progeny
nor its ancestors. Going forward, the BOLT-
derived EPDs will make use of genomic
information along with all pedigree,
performance, and progeny information, in
one step; thus, eliminating the post-
evaluation blending formula. Another crucial
difference is that now, even animals who
have not been tested will be impacted by
genomic test results from relatives – this
can cause some major change in
non-genotyped animals.
2)
Updated External EPDs – The IGS evaluation
makes use of information from externally-
16 | SEPTEMBER 2018
supplied EPDs. From time-to-time this
information needs to be updated as more
information is gathered by the supplying
organization and especially as those
organizations make changes to their
genetic evaluation that impact those EPDs.
Below, you’ll find a description of key changes in
some of the most commonly asked about EPDS.
Calving Ease (Direct and Maternal) – In addition
to the changes impacting all traits mentioned
above, substantial updates were made that
caused some re-ranking for CEM and CED.
Tables 1 and 2 show some key differences in
rank among the NALF breed categories.
1)
Contemporary Groups with no Variation:
In the past, if calving scores were submitted
on heifers and there was no variation in
the scores (all 1’s, for example), the
performance information on those calves
was not used. Now, with single-step EPDs
powered by BOLT technology, data on
animals in contemporary groups without
phenotypic variation can be used. For CED
and CEM, calving scores from contemporary
groups in which none of the heifers required
assistance can be used. This means
there is more information available for
genetic prediction in the BOLT-powered
EPDs, which should mean less bias.