Genetics
Do Some Selection Tools Result in
Unintended Consequences?
Justin Sexten, Ph.D., Director, CAB Supply Development
You hear more about mature
cow size and growth potential
of calves, now that profit
ebbs and flows with the cycle.
We’ve written about mature
size, but not much about
how to use the relevant tools
to change it. So now, let’s
examine the strategies and tools
available, and the unintended
consequences of ignoring them.
Commercial breeders can draw
on more selection tools than
156 | JUNE/JULY 2018
ever before to improve the next
generation of cows to match the
market and ranch environments.
Genomic testing can identify
sires in multi-bull pastures
while indexing heifer genetic
potential and sorting outliers
for adaptability and docility. You
could start with cow records
and docility notes early on,
then cull heifers at weaning
that don’t make the obvious
phenotypic and docility cuts.
With all the concern of
increasing mature size in
the cow herd, I am curious:
how many heifers do you
cull at weaning for being too
large? Most will not hesitate
to cull the small end, but my
discussions suggest few sort
off the larger heifers. Early
genomic testing helps us find
those with greater potential