Even if you do everything right as a beef cattle producer, sometimes things go wrong. Some issues are obvious, but others may be hidden – deep in the heart of your animals.
Presenting “A Continued Concern: Bovine Congestive Heart Failure” at the recent CattleCon ’24, Kelli Retallick-Riley, a quantitative geneticist with Angus Genetics Inc., talked about the disease, which she said first gained some notoriety in 2018 and 2019.
Bovine congestive heart failure (BCHF) results in “a severe remodeling of the heart,” Retallick-Riley explained. Outwardly, there’s an extension of the jugular vein and edema (swelling) visible in the brisket area. When the animals undergo necropsies, hearts that are distended and U-shaped are found instead of healthy V-shaped hearts. A lot of the muscle from the left ventricle hypertrophies.
“We really focus on that one organ but we need to think of the whole animal,” she said.
The disease is very similar to high altitude disease (HAD), in which the pulmonary artery begins to constrict and thicken in response to low oxygen being transported throughout the animal’s body. In both cases, vasoconstriction and arterial smooth muscle hypertrophy, which results in a lot of pressure. There’s then pulmonary hypertension, pressure and eventual heart failure.
However, HAD is almost always found in cattle raised at elevations of 5,000 feet and higher. In BCHF, the condition most often affects feedlot cattle at low to moderate altitudes. The direct cause for BCHF is currently unknown, but the heart remodeling is similar to that of animals suffering from HAD.
“The big question is are BCHF and HAD the same?” Retallick-Riley asked. “We’re working on finding that out … There are similarities between these two conditions but questions still go unanswered. We may never be able to completely eliminate the disease [BCHF], but how can we think of ways to reduce the risk of an animal going into BCHF at lower elevations?”
(One thing that has worked for HAD is selecting bulls with lower pulmonary arterial pressure (PAP) scores, as they are successful in producing progeny with lower PAP scores. Less pressure means less risk of death from that disease.)
Retallick-Riley noted that as BCHF has gained recognition, lots of anecdotal stories came to the surface. Producers would say things like it only affects cattle in their last days of life; it only affects heavyweight, high performing steers; it only affects black-hided cattle; it’s only found in feedlots at elevations of 4,000 feet or higher.
BCHF doesn’t affect only black-hided animals – or any particular breed. Photo by Enrico Villamaino
“Then preliminary research from the U.S. Meat Animal Research Center and the University of Nebraska-Lincoln found a subset of markers to control BCHF,” she said. “They identified 20 or 21 genetic markers that control the disease.”
With a small set of markers like that, Angus Genetics Inc. wanted to validate it in a large population.
They contacted the Beef Cattle Institute at Kansas State to look at three years (2017-19) of data from almost 4.6 million head of cattle. They determined that only 0.07% of that number placed on feed were called BCHF deaths – about 4% of deaths were attributed to it, however.
So they wanted to know if they could identify the animals that were more susceptible. BCHF was found spread across the feeding phase. Placement weights resulted in little to no difference is susceptibility. Breed didn’t matter, as it can affect all of them as well as dairy and dairy x beef crosses.
However, arrival weight and disease category did have an impact. The researchers saw a higher instance of succumbing to BCHF in cattle with acute interstitial pneumonia and complex disease (meaning they were treated for more than one disease or repeats of the same disease).
Dr. Tim Holt, a professor in the College of Veterinary Medicine & Biomedical Sciences at Colorado State, began a heart scoring system similar to a body scoring system in post-mortem animals to see if there was any correlation there.
“It’s good for genetic measures – and it’s easier than getting a PAP,” Retallick-Riley said. “It helps to estimate the heritability of heart score remodeling.” Like BCS, heart scores range from 1 – 5; 1 and 2 are normal, 3 – 5 have higher amounts of remodeling. The scores can also be used to tie to other issues with the aim of producing healthier hearts.
Researchers rarely see 5-scored hearts, though, because those animals die before being processed. Scores of 4 often resulted in lower carcass weights in a study of 1,400 Angus-influenced animals. In total, this study found about a 28% chance of heart remodeling heritability.
Another project in 2022 used animals with known heritage to cast a wider net for heart score data, called the Heart Health Initiative. In that research, they found a 23% chance of heart remodeling heritability.
“How do we use this information to select cattle with less heart remodeling? If we have a trait that has heritability that means we can make genetic progress for that trait, so if we put direct selection pressure on heart score alone, we’re going to create cattle with less degrees of remodeling,” Retallick-Riley explained. “We’re also probably going to decrease carcass weights on these animals as well. Maybe there’s some multi-trait index that we’re going to have to fit in order to conquer this beast.”
She added that the heart score is not the trait of interest, though – dying of BCHF is.
“When we view an issue in the beef industry, we never solely focus on genetics,” Retallick-Riley concluded. “What else can we do to avoid BCHF deaths in the feedyard? It’s about 28% heritable – what about that other 72%? What’s happening in the life of that animal that maybe we can avoid – a stressor that could lead to cardiac death in the future?”
by Courtney Llewellyn
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