A piece of the feedlot death puzzle may have clicked into place.
On Jan. 13, Dr. Michael Heaton, a research microbiologist at the U.S. Meat Animal Research Center, presented preliminary findings at the International Plant and Animal Genome conference held in San Diego. The findings strongly suggest that congestive heart failure in feedlot cattle has underlying genetic factors.
Brisket disease—also called “pulmonary hypertension”—is well known as an altitude problem. In general, brisket disease occurs when cattle are not getting enough oxygen. This can be due to lung injury, altitude, or other factors. This forces the heart to work harder. This eventually results in the characteristic swelling of the brisket area due to edema—pooling liquid within the body—that led to the catch-all phrase “brisket disease.” Death often follows observable symptoms.
But brisket disease—or something very similar—has been observed with growing frequency in feedlot cattle not kept at elevation. This has been called “feedlot cardiac death.”
Or, as Heaton and research coauthor Dr. Brian Vander Ley, Veterinary Epidemiologist from University of Nebraska-Lincoln, have been calling it: “Bovine congestive heart failure” or BCHF. They define it as pulmonary hypertension that culminates in right ventricular failure and death.
They additionally have found “Congestive heart failure in feedlot cattle has major underlying genetic factors.”
In their study, Heaton, Vander Ley, and other researchers collected genetic samples of 102 feedlot cattle showing clinical symptoms of BCHF and samples of 102 unaffected pen mates. Study cattle were majority black-hided commercial fed cattle from two feedlots each in Nebraska and Wyoming. Elevations of the feedlots ranged from 3,816-4,198 feet.
Genetic samples involved analyses of 563,042 filtered SNPs (single nucleotide polymorphisms). According to the abstract poster presented by Heaton at the conference, the analyses located 21 different SNPs that were associated with BCHF. Two were especially strongly associated; the arresting domain-containing three protein (ARRDC3) and nuclear factor IA (NFIA) genes. Mutations on portions of these genes had the best statistical support for association with BCHF.
“Animals with either or both the ARRDC3 or NFIA risk factors were approximately seven- and 15-fold more likely to have BCHF compared to those without,” summarized the abstract poster.
What does this mean?
Very simply, identifying an associated genetic risk factor for BCHF means cattle can be screened for it. If it can be screened for, breeders can select against it.
“We don’t know exactly what ARRDC3 and NF1A have to do with the mechanism of this disease, but we are relatively confident that if you breed for the relatively low risk versions of those two markers, that the offspring of those animals will have fewer issues of heart failure than they do now,” summarized Vander Ley when speaking to WLJ last week.
“I would call it pretty solid association data, and the p-values speak to that,” he continued, referencing a common means of measuring strong associations. However, this is the very beginning of what will likely be a long process.
“What we don’t have is prospective validation,” Vander Ley cautioned. “What we need now, and what we’re still working on—and this is in progress—is we test cattle that have not yet developed disease, find out who’s at risk, and see if the cases actually happen in those. That’s what we’re working on right now. Once we get that done, we’re in a solid position to say this is a very valuable tool.”
Protocol vs. utility
Despite being presented, the research—titled “Association of ARRDC3 and NFIA Genes with Bovine Congestive Heart Failure” on the abstract poster—has not yet been run through the peer review process or published in an academic journal. Vander Ley acknowledged that it is unusual for unpublished research to be presented or researchers to talk to news media about unpublished works.
“The conundrum we deal with is, if we wait to go through the entire peer review process, there can be a huge delay between the development of a good tool, and anybody finding out about it in time to use it,” he explained.
The peer review and publishing process can take several months to well over a year.
“We could easily really delay this process for months to years by doing that and we felt strongly that—because we have really put it through its paces and tried to poke holes in it ourselves—there is a chance that this is a benefit right now.
“Breeding season is right around the corner and there’s an opportunity for people who were hard hit by this particular disease process to start doing some good in their own herd.”
According to the abstract poster, feedlot cattle in the Western Great Plains have up to 7 percent mortality to BCHF.
“So, what we are attempting to do here is throw the red flag and say, ‘Hey, this is not through the whole process yet,’” Vander Ley continued. “The caution is, this is a first step. We are confident it’s a good step, but it’s not the last step. This isn’t the only tool that we’re going to develop.”
He also noted that there are limitations to the current research.
“What we can say is if you’re in this area with the same kind of cattle that we sampled to discover this, that it is very likely these results will be applicable to your situation,” he said. He added that if a producer has a significantly different situation from the research settings—mostly black-hided commercial fed cattle in Great Plains feedlots at about 4,000-foot elevation—the findings may not be as applicable.
“We try to caution people about the fact that it’s not published yet—it will be, but it’s not yet in a peer-reviewed fashion anyway—and that they need to understand the limitations before they implement.”
He also explained that, despite stressing cautions and limitations, the researchers are very excited and confident in their findings.
“It sounds like I’m walking it back all over the place. We’re not walking it back. We’re really confident,” he said. “But with all science there are limitations. The difference is whether somebody told you about the limitations or not.”
Vander Ley encouraged everyone interested to view the abstract poster on the research. It is currently available HERE.
He also welcomed anyone interested in the details of the research to talk with him. His publicly-available contact information is 402-762-4503 and firstname.lastname@example.org. — Kerry Halladay, WLJ editor