Breed Improvement
What to Expect with Multi-breed Genetic
Evaluation powered by BOLT
By IGS Genetic Evaluation Team and Consultants
Change can be a scary concept to some yet sought
after by others. Many breeders wonder about the
changes on the horizon once the new evaluation,
Multi-breed Genetic Evaluation powered by BOLT,
is fully implemented. That change may be nerve-
racking but in reality, things should change.
Why invest in new and improved methods if you
get the same answers? Here are key changes
to expect with the new genetic evaluation:
1. Movement of EPDs and reranking. EPDs will
change especially in younger, lower accuracy
cattle. Members should expect movement
in lower accuracy cattle, as seen in the existing
evaluations, because they may have new progeny
data reported. Some cattle will move in a favorable
direction while others will do the opposite.
Keep in mind even if the EPDs get worse, the
prediction of them is more accurate. With Multi-
breed Genetic Evaluation powered by BOLT, we
will have more accurate EPDs earlier in an
animal’s life.
2. More accurate accuracy. This idea takes a little
time to sink in. The accuracy reported for each EPD
will be more directly calculated and thus closer to
the “real” accuracy. The methods to solve accuracy
directly are extremely difficult and take a lot of
computer power. With the previous Cornell
software it was not possible to solve for accuracy
directly so an approximation method was used to
estimate accuracy for each EPD. There were
inherent flaws with approximating the accuracy
with the previous method. Now with BOLT
software, the accuracy reported with the
EPD will be more reliable.
3. Reported accuracies will tend to be lower. One
of the inherent flaws in the approximation
methods used to find accuracy in the previous
evaluation, and in all evaluations not produced
through BOLT, was they frequently overestimated
accuracy, especially for younger animals. This
was known for a long time, but there was no
way to calculate the accuracies directly. With
BOLT, having accuracy more directly solved
results in a more reliable accuracy but that
22 | MAY 2018
accuracy will often be numerically lower than the
previous evaluation would predict. However, the
new reported accuracies with BOLT should better
represent the possible changes for the EPDs.
4. DNA testing will have a larger impact. With the
switch to BOLT software, IGS will use Single-step
genomic evaluation on all EPDs (currently using
Single Step for Stayability EPDs). Single-step
uses the DNA markers, pedigree information, and
phenotypic data simultaneously in the prediction
of the EPDs. Previously molecular breeding
values (MBVs) were calculated from the genomic
information and those MBVs were blended
separately into the EPD prediction. The Single-
step method squeezes more information from
the DNA markers than the previous approach
allowed. Also, there are biases inherent in the
blending process that aren’t a problem with
the Single-step approach. Additionally, with
Single-step, the genomic information will not
only enhance EPDs for the genotyped animal but
also will be used in the EPD estimates of relatives.
5. Weekly genetic evaluation runs. With the
horsepower behind BOLT, IGS can run genetic
evaluations weekly. This has many benefits. It
allows members to get more immediate feedback
after submitting their records. If members miss
a deadline, they can catch the next evaluation
run the following week. It allows for more
accurate EPDs throughout the year and faster
incorporation of the genomics. This also means
the EPDs put in print will quickly be outdated.
Genetic evaluation is not stagnant. There will
always be improvements as new research in animal
breeding, genomics, and statistics advance. BOLT
software is revolutionary in the innate flexibility, the
computational power, and the statistical methods
made possible using this software. Multi-breed
Genetic Evaluation powered by BOLT promises
more accurate EPDs, accuracies, and better use of
genomics all delivered to you on a weekly basis. I