BOLT
Multi-breed Genetic Evaluation powered by BOLT
Are the New BOLT-Derived EPDs More Accurate Than Previous Cornell EPDs?
By Mahdi Saatchi, Rohan L. Fernando, Lauren Hyde, Jackie Atkins, Steve McGuire, Wade Shafer, Matt L.
Spangler, and Bruce Golden, IGS Genetic Evaluation Team and Consultants.
The ASA and International
Genetic Solution (IGS)
partners invested in a new
and improved genetic
evaluation software called
BOLT to replace the Cornell
EPD evaluation system. Among
other benefits, this enables the
use of single-step methods
for incorporating genomic
information into the National
Cattle Evaluation instead of
the blending approach. In the
Single-step process, the DNA
marker genotypes are directly
incorporated into the genetic
evaluation along with the
phenotypes (performance data)
and the pedigree. As a result,
the genomic data has an impact
not only on the genotyped
individual, but also on all the
relatives of that genotyped
individual. This allows for
the genomic information
to improve the accuracy of
non-genotyped relatives.
The Multi-breed Genetic
Evaluation powered by BOLT
squeezes more information from
the DNA markers by allowing for
certain DNA markers to have a
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larger influence on predicting
the genetic merit of an animal
than other DNA markers
while some DNA markers to
have no effects on trait(s) of
interest. This model is closer
to what we expect based on
biology where some parts of
an animal’s genome (or genes)
play more important roles than
other parts of its genome (or
genes). This is unique to the IGS
Single-step method compared
to other organizations where
the DNA marker information
is used to adjust relationships
among the individuals.
Are the BOLT EPDs more
accurate than the Cornell
derived EPDs in the real world?
To answer this question,
we performed a validation
study where we ran a data
set (pedigree, performance,
genomics) through both
genetic evaluation software
(BOLT and Cornell) to compare
the accuracies of the EPDs
produced. To enable a fair
comparison, we removed the
performance records of animals
born in 2015 and later from the
evaluation in both systems to be
used as progeny performance
records for validation purposes.
Table 1 shows the correlations
between EPDs and progeny
performance of non-genotyped
sires evaluated in both systems
that have progeny born in
2015 or later with recorded
birth, weaning, and yearling
weights. As shown, the BOLT
EPDs are more accurate than
Cornell EPDs as the correlations
are higher for BOLT EPDs with
sires’ progeny performances.
Table 1- The correlations between BOLT vs. Cornell EPDs with progeny performance of
non-genotyped sires for birth, weaning and yearling weights.
Trait N of Sires BOLT Cornell
Birth weight 29,154 0.34 0.27
Weaning weight 21,571 0.29 0.19
Yearling weight 10,849 0.26 0.20