Page 42 - D Red Select Sale – Dec. 8, 2018 North Dakota Red Angus Female Sale.

What drives genetic progress?
What drives genetic progress?

by Ryan Boldt, RAAA Director of Breed Improvement

Cattle breeders are provided with many metrics to describe the genetic merit of
cattle. These include adjusted phenotypes, ratios and EPDs. However, these tools do
vary in their ability to accurately describe genetic merit. Red Angus has long been
a strong advocate for making selection decisions based on EPDs, but there are also
other factors that infl uence the rate of genetic progress within a herd.

The rate of genetic change is infl uenced by selection cated to improving the accuracy of selection tools. Many
intensity, generation interval, genetic variation and ac- advancements have been made through the use of better
curacy of selection. Each factor plays an important role statistical models to evaluate cattle performance data, use
in the overall genetic progress that can be realized. of genomic information, and the implementation of Total
Herd Reporting to collect data on all animals within a
Selection Intensity and Generation Interval herd (thereby avoiding partial reporting).
The fi rst two parts of this equation are the decisions
of selection intensity and generation interval. Selec- Currently, RAAA is on the cusp of another major mile-
tion intensity is how superior the animals retained as stone through the release of the IGS Multi-Breed analysis
replacements are compared to all available replacement powered by BOLT. This system is another leap forward
candidates. The measurement of choice for this decision in improving the accuracy of selection in Red Angus
is EPDs. Another factor is generation interval, which rep- cattle. With this new BOLT-driven system, EPDs are cal-
resents the amount of time needed to replace one gen- culated using over 17 million pedigree and performance
eration with the next. The challenge becomes that these records.
two factors are generally inversely related. In order to
have a higher selection intensity, fewer replacements are In addition, the BOLT software has the ability to include
retained, which lengthens generation interval. If genera- genomic information directly into EPD calculation pro-
tion interval is shortened a higher percentage of possible cess. Not only that, but the models used for EPD calcula-
young selection candidates must be retained. Therefore, tion are more advanced.
it is important to optimize the relationship between these
factors. In short, this new evaluation allows us to more accu-
rately describe cattle’s genetic merit. While these assets
Genetic Variation of the evaluation are impressive some still may require
The next factor is the amount of genetic variation avail- more proof that the new EPDs are doing a better job of
able for a trait(s) of interest. This factor shows within a predicting genetic merit. The IGS genetic evaluation
group or population how large the spread is in the genet- team has validated the BOLT EPDs to show that they are,
ic merit for a trait(s) of interest. This factor is important in fact, more accurate than the EPDs derived from the
because if the spread of genetic merit is narrow it be- previous evaluation methods.
comes more diffi cult to make genetic progress, however,
if the amount of variation is large, then genetic progress On the facing page is a short report that shows the vali-
can be executed more quickly. dation of the BOLT EPDs compared to the previously
used Cornell software. The results of this analysis – us-
Accuracy of Selection ing multiple metrics of comparison – showed that the
The fi nal factor that infl uences the rate of genetic change BOLT-derived EPDs were indeed more accurate. What
is the accuracy of selection. Accuracy of selection refers to this means is that the new BOLT EPDs should allow for
what metric a producer uses to make selection decisions. more accurate selection decisions, that should in turn
Out of the available selection tools, EPDs are the most ac- lead to more rapid genetic progress.
curate and effi cient method to make genetic change. The
RAAA released its fi rst set of genetic predictions in 1974. Better selection tools =
Since that time, considerable research has been dedi- faster genetic progress in your herd. ■

Reprinted with permission from the September 2018 American Red Angus Magazine

40 – North Dakota Red Select Sale Catalog online at ndredangus.com