Commercial cattlemen can use genomic information for more accurate EPDsWritten by Gayle Smith
The added value of genomic information to expected progeny differences (EPDs) in beef cattle might produce more accurate EPDs, especially in young, unproven bulls.
The evolution of genomic information isn’t designed to replace EPDs but to make the information more accurate, according to Matt Spangler, University of Nebraska beef geneticist.
The use of genomic information can be particularly helpful for commercial cattlemen. If a commercial producer is evaluating two yearling bulls with identical EPDs, which should he choose?
If additional genomic information is available that shows one bull has a calving ease of +11, while the other is -2, that producer could have made a serious mistake without this additional information, Spangler said.
This technology can really be useful in younger animals that don’t have a lot of EPD data available.
Genomic testing has also been used as parent testing to ensure animals have the correct pedigree but it has now evolved into collecting data for complex traits, which are traits influenced by numerous genes that have EPDs.
“When genomics first came into the marketplace, bull sale catalogs were filled with a plethora of information,” Spangler said. “A lot of that information was useless because the ratios, EPDs and accuracy were too low.”
Nucleus breeders who produce seedstock for other seedstock operators need to be the first to implement genomic information into their programs.
“Within each breed, the nucleus population is what drives genetic change,” Spangler explained.
“Seedstock producers can utilize this information to make genetic change quicker. They can use fewer animals because they have more accurate data and more confidence in the animals they use,” he explained.
Spangler discussed the current application of genomic tools, including testing for genetic defects, paternity, genomic-enhanced EPDs and the potential for marker-assisted management. His take-home message to seedstock producers is to continue to collect and routinely record phenotypic information, even if they collect genomic data.
“As a seedstock producer, we still need to weigh our calves at birth,” he said. “Genomic technology only makes these tools stronger. It does not replace them.”
Spangler sees genomic predictions being particularly valuable to seedstock producers with young, unproven bulls. Before genomics were available, producers used EPDs to select a sire and then had to test the bull by producing many offspring to improve accuracy for the traits carried by that bull.
“Genomics and the corresponding marker-assisted or genomic-enhanced EPD, have become a reality,” Spangler explained.
“Within a breed, genomic predictions have proven to add accuracy for several traits, particularly to young bulls,” he added.
The problem with genomic testing, Spangler continued, is it tends to be breed specific.
“If a test was developed for Angus, it will work best for Angus cattle. The test will not be as accurate if it is used in other breeds. An Angus test used on Charolais will not work as well, and we will be really disappointed if we use it in Bos indicus cattle,” he explained.
In fact, Spangler discussed a study where the application of a genomic prediction test developed for Angus was used on the closely related Red Angus. The results showed a substantial amount of variation and were deemed inaccurate, he said.
Many producers question whether a genotyped bull is better.
“His EPDs should be more accurate, but it does not make him a better bull,” Spangler explained. “As accuracy increases, some bull’s EPDs will go up, and some will go down. We don’t need to understand genomic test results. They are supposed to be incorporated into the EPDs to make them more accurate. Just look at the EPD.”
Originally, genomics was developed to help researchers pinpoint genetic defects like marble bone. Before this testing was available, Spangler said animals were purged based on their pedigree.
“We can now use genetic testing to pick out the carriers and determine what to do with them,” he explained. “Without this testing, some breeds would have been decimated in the past few years.”
Genomic testing will also continue to be developed and used to identify genetic defects in cattle.
“There are many more genetic defects out there,” he said. “We just haven’t identified them all yet.”