BOLT
Frequently Asked Questions: Multi-breed Genetic
Evaluation powered by BOLT
By IGS Genetic Evaluation Team
The new genetic evaluation, Multi-breed
Genetic Evaluation powered by BOLT, offers
groundbreaking advances in the prediction
of EPDs for the IGS group. Here are some
frequently asked questions and answers to help
you better understand the new evaluation.
1.
What are the key features of the
Multi-breed Genetic Evaluation powered
by BOLT?
• Faster and more automated
system allowing for frequent gene
• Improved use of genomic data
with Single-step.
• Improved methodology for predictions
of all traits.
• More accurate accuracy.
• More flexibility to add additional traits
or change methods for future
improvements.
2. How is IGS’s single-step approach different
from blending for genomic evaluation?
The blending approach uses separate steps
to calculate genomically enhanced EPDs. This
approach requires two steps. The first step is to
estimate the effects of DNA markers through a
process called “training” or “calibration”. These
effects are then used to calculate molecular
breeding values (MBVs) on genotyped animals.
The MBVs are then combined with traditionally
calculated EPDs to enhance the accuracy of
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the traditionally calculated EPDs. The blending
process is only performed on genotyped animals.
Befitting its name, the single-step approach
calculates genomically enhanced EPDs in one
step — using DNA, pedigree information, and
phenotypes simultaneously. As a result, the DNA
information not only improves the accuracy of
prediction on genotyped animals, but also on the
relatives and contemporaries of the genotyped
animals. In a sense, all animals are genomically
enhanced under the single-step approach.
There are also issues inherent in the blending
process that are solved with single-step. Similar
to the fact that only reporting phenotypes on a
selected group of animals in your herd can lead
to less informative (and more biased) EPDs with
traditional evaluation, problems can exist with
blending as it only involves genotyped animals
— and genotyped animals tend to be highly
selected. However, because single-step includes
information from non- genotyped as well as
genotyped animals, the issues are corrected.
3. How is the Multi-breed Genetic Evaluation
powered by BOLT different than other
single- step models used in other genetic
evaluations?
It is well established that DNA markers vary
greatly in their effect on traits — ranging from
a large to no impact. To leverage this biological
fact in a statistically advantageous manner, the
BOLT single-step method only utilizes markers
that have a meaningful impact on the traits of
interest, while ignoring those that have little to no