Genetics
Snowball Effect: Genomics and Advanced
Reproductive Technology
By Justin Rhinehart, University of Tennessee
Most of the articles I write
focus on technologies that
apply to a wide scope of cattle
producers. I usually have the
commercial cow-calf sector in
mind even when I write about
technologies that are used
predominantly in seedstock
production. This article is a bit
different as I aim to describe
how the combination of two
technology categories are
being used together to make
the metaphorical snowball of
genetic advancement grow
and roll faster. A handful of
progressive seedstock producers
are testing DNA collected from
embryos to determine which
embryos they will transfer to
recipient cows. Culling through
the embryos allows them to
only transfer those that have the
best opportunity to produce a
very specific type of calf without
wasting their limited resources
on less valuable calves.
Here is how it works using
embryo transfer as an
example (this approach can
also be incorporated into IVF
procedures). First, the donor
cow is set up for normal
superovulation and embryo
transfer and the embryos are
collected. The genomic analysis
technology is started prior
to the embryos being frozen
by taking a few cells from a
carriers of that abnormality.
specific part of the embryo with
Although I am not aware of
a small needle guided under a
producers that are doing it, this
microscope.
After the
Culling through the embryos allows
biopsy is
them to only transfer those that have
taken, the
embryos are
the best opportunity to produce
frozen while
a very specific type of calf without
the genomic
analysis is
wasting their limited resources on
completed.
less valuable calves.
There are a
few additional
steps that have to be done
process could also allow for
to get enough DNA from the
multi-sire AI to a single flush by
smaller sample. After that, the
incorporating parentage testing
process is the same as normal
with the genomic analysis. To
genomic analysis; the same
make the technology snowball
group of genes are analyzed,
even larger, the possibility exists
and that analysis reported to the
to use gender-sorted semen
breed association to enhance
from two different sires, one
the accuracy of specific EPDs.
sorted for heifers and the other
for bulls, and each embryo
When the genomic analysis is
genetically tested for sire and
completed, the actual data and/
gender to generate replacement
or the genomically-enhanced
heifers and herd bull prospects
EPDs are used to decide which
from two different sires in the
embryos will be thawed and
same embryo collection. This is
transferred into recipient cows.
already done in IVF procedures.
Additionally, the gender of
each embryo can be identified
The reason a seedstock
so that only bulls or heifers
producer would want to go
are transferred to meet the
through all this trouble might
objectives of that specific
not seem obvious. But, consider
mating. For some breeds,
how many resources (land, time,
testing for genetic abnormalities
and money) are dedicated to
could reduce or completely
each recipient cow that carries
eliminate the production of
an embryo to term and then
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