Heartache: Bovine Congestive Heart Failure A Growing Concern
By
GREG HENDERSON August 8, 2022
Veterinarian Randall Raymond sees too many dead cattle that are close to the finish line.
“Those late days-on-feed mortalities are both frustrating and expensive,” says Raymond, director of research and veterinary medicine at Simplot Land and Livestock.
Indeed, the incidence of bovine congestive heart failure (BCHF) is increasing throughout the industry, especially as cattle are fed to heavier end points.
Over the past several years, late-term losses have spiked to 30 to 40 mortalities per week in one major feedyard during peak heat season due to bovine congestive heart failure. Additionally, several catastrophic events have been catalogued in the Northwest and Midwest in the past few years where hundreds to thousands of animals have died in significant heat stress events lasting 48 to 72 hours. These devastating losses have prompted Raymond and Simplot, which operates two large feedlots in the Pacific Northwest, to invest in research to identify root causes and robust solutions for BCHF.
Randall Raymond, DVM
Simplot began with intense training of feedyard personnel to accurately diagnose the stages of heart failure upon gross necropsy. Simultaneously, pen riding staff were trained to assess the subtle and early signs of cattle experiencing cardiac insufficiency. Simplot then partnered with Gencove Inc., a company that develops software for genome sequencing applications in agriculture and humans, to launch a research project that recorded heart and lung scores on 20,000 cattle from a diverse cattle population representing all major beef and dairy breeds.
Cattle were phenotyped at harvest using a standardized cardiac scoring system.
Incidence of end-stage heart failure varied significantly by breed type, with more than 5% of black-hided calves in normal scheduled harvest shipments assigned heart scores consistent with end-stage heart failure. Simplot says the project confirms a dramatic prevalence of this syndrome in U.S. cattle, a condition it says can be greatly reduced through genetic selection.
“Our work indicates that the heritability of this trait is about 35%, which is as high as any of the highly heritable traits we have been successful in changing over time such as hot carcass weight, average daily gain or marbling,” Raymond says.
Separate research agrees with Simplot’s findings. Brian Vander Ley, DVM, Great Plains Veterinary Educational Center (GPVEC), Clay Center, Neb., says significant epidemiologic evidence points to a genetic component to the disease.
“Our assumption was if there is a genetic cause, there’s a change in the genome causing a biological outcome,” Vander Ley said. “Our goal was to find genetic markers directly associated with the disease outcome.”
A research project led by then U.S. Meat Animal Research Center (USMARC) and GPVEC sought to pair closely matched animals that had heart failure with animals that did not, but still had similar genetic backgrounds and similar management.
“We paired them up and looked for differences,” Vander Ley says. “We found two regions were associated with end-stage heart failure in feedlot cattle. Calves with risk genotypes in both regions had 28 times higher odds of disease compared to calves with risk markers in neither region.”
For Simplot the issue is costly.
“One of the most surprising outcomes of our heart scoring efforts has been the realization that the losses we have experienced at the feedyards are only the tip of a very large iceberg,” Raymond says. “Without aggressive and accurate interventions, we can expect this issue to continue to increase in intensity and frequency in the future. Obviously, when those cattle are worth roughly $2,500 and have accrued nearly $1,200 in feedyard costs it’s a significant economic loss, in addition to the loss in morale from professional feedyard staff and cattle owners.”
As a partial solution, Raymond says from May to September Simplot ships 30 to 80 head per week to the packer in what he termed “emergency shipments.”
They’ve found through heart scoring postharvest about 40% of those cattle are end-stage heart failures.
“So, we have the luxury of artificially reducing our number of BCHF deaths because we have close proximity to a packing plant of which Simplot is part owner,” Raymond says.
Simplot, using the Gencove software platform, has developed what it calls a “robust prediction model and novel EPD to provide tools” necessary for the industry to select cattle less likely to suffer morbidity and mortality losses from BCHF.
Gencove’s low-pass whole genome sequencing and analysis software technology allows for high-throughput. Previously, high throughput was achieved only with genetic testing technologies using segments of the genome.
Jesse Hoff, agrigenomics specialist for Gencove, says advantages of low-pass sequencing include genetic marker selection flexibility, accelerated turnaround and higher return on investment.
“Blinded and replicated validation of a genomic EPD calculated from (the Simplot) population indicates a moderate to high prediction accuracy is possible across multiple breeds,” Hoff says.
Both Simplot and the USMARC/GPVEC studies suggest BCHF often occurs in cattle described as well-bred and well-managed, but the relationship between BCHF and performance outcomes remains unknown. The USMARC/GPVEC research indicates the “frequency of risk alleles (for BCHF) is higher in Angus and Red Angus,” Vander Ley says.
The research identifying specific breeds matches observations at Simplot’s feedyards.
“We’ve learned that the top performing cattle, which all cattle feeders are looking for, are the ones most likely to exhibit BCHF symptoms,” says Tom Basabe, president of Simplot Land and Livestock. “Virtually all of the cattle we’ve had problems with are black.”
Angus Association Pursues A Solution
Th e rising incidence of BCHF might be partially influenced by genetic selection for cattle that are more efficient converters, but the American Angus Association says the jury is still out. It is supporting additional research that will be available in the near future.
“We’ve been researching this industry topic for some time,” Angus CEO Mark McCully tells Drovers. “The Association has supported research at Kansas State University trying to determine prevalence, genetic background and days on feed.
What we are learning is that it isn’t quite as cut and dried as you might expect, particularly surrounding early assumptions relating to growth rate, days on feed and breed. Since Angus genetics make up such a large portion of the commercial beef industry, and even the genetics of other breeds, we are diligently pursuing sound and science-based solutions to create selection tools for cattlemen.”
Feedyards have always had sudden deaths, but the problem increased over time, Basabe says. While the prevalence of BCHF is higher, the genetic risk for BCHF can be reduced, either with EPDs or DNA testing. Researchers are confident there are multiple risk factors required on top of genetic predisposition for an animal to suffer from clinical heart failure.
“But, they’ve (Simplot and Gencove) found something that’s very heritable and can be improved with breeding. That’s the same outcome we found,” Vander Ley says. “In our case, instead of EPDs, we can take a DNA sample to test for the genetic markers. If markers are present, we won’t use those animals for breeding.”
Through EPDs or DNA tests, the risk for BCHF can be significantly reduced quickly. Because the genetic risk factors in the USMARC/GPVEC study follow a recessive inheritance pattern, Vander Ley says use of “no-BCHF risk” bulls should remove the risk of heart failure in one calf crop, genetically, but the herd will still have carriers.
“It takes a longer time to get rid of the carriers, but it doesn’t take very long to get rid of the risk with a recessive trait,” Vander Ley says.
Basabe says Simplot has already begun the process to reduce the incidence of BCHF on its ranches.
“We’re going to test all of our bulls,” he says. “We buy a lot of bulls each year, and we’re going to begin selecting bulls that we test first. We’ve tested lots of cattle, and we have the data and now we’ve got the tools to make a difference.”
Simplot hopes setting an example through the investment to develop the EPD, other seedstock breeders will use the tools to begin the process of reducing BCHF in herds nationwide
“We’re hoping our investment will help change the course of this condition,” Raymond says. “We’re trying to create awareness about BCHF and the financial losses that can be avoided across the entire industry.”
(Comment: I know with closure of area auction yards, many of ranchers in my former area contracted with S. CA feedlots. The feedlots provided the Angus bulls to breed with local stock. They were trying to standardize size for easier processing. )
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