Performance Line
Making Sense of Genetic Trend
By Tonya Amen, National Center for Beef Excellence
If you’ve attended a presentation about Breed
Improvement, EPDs, or genetic selection, it’s
likely you have seen a table or chart representing
genetic trend. Indeed, each breed association
publishes a new genetic trend table at least
once per year, and often-times more frequently.
NALF releases a new genetic trend table bi-
annually, each time that new EPDs are released.
Typically, genetic trend tables are depicted
as the average EPD for animals born in each
year for the trait of interest. These charts or
tables can be used to illustrate the traits that
a breed has placed selection pressure on and
the direction of that selection. They can also be
used to illustrate those traits that are genetic
correlated with traits that have been under
selection and have thus experienced inadvertent
directional change. Or, other times, it illustrates
for which little change has been made.
Using Figure 1 below, it appears that Limousin
breeders have been selecting for improved
calving ease over the last 20 years. Compared to
animals born in 1998, 2017-born animals average
Figure 1. NALF genetic trend for Calving Ease Direct and Calving
Ease Maternal.
18 | APRIL 2018
nearly 5 percent higher (more favorable) for CED.
Likewise, in Figure 2, we see that both weaning
and yearling weight have experience upward
selection pressure in the last 20 years, with 2017-
born animals having 23.1 pounds heavier weaning
weight EPDs on average, and 42.9 pounds heavier
average YW EPDs than those 1998-born animals.
Figure 2. NALF genetic trend for weaning weight and yearling weight.
For a seedstock breeder, perhaps more important
than genetic trend for the entire breed is
understanding where your herd fits and how
effective your selection methods have been for
the traits that are of importance to you and your
customers. Thanks to the robots on-line breeder
portal, this options exists for NALF members. As
illustrated in Figure 3, once you’ve logged in to
limousin.digitalbeef.com using your member
code and password, you’ll find the “Genetic Trend”
feature in the “Tools” section under “Ranch/Person.”
Once you’ve selected the “Genetic Trend” tool,
you’ll be directed to a page with tabs for each trait
along the top of the page, as well as summary
statistics by year for the selected trait (Figure 4).
Under the summary statistics, you’ll see a graph