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Brisket Disease Research

Genetic heritability of pulmonary arterial pressure is similar to that of yearling weight.

Some cattle at high elevations suffer pulmonary arterial hypertension, often called brisket disease, which leads to congestive heart failure. Susceptibility is inherited. A test developed in humans for measuring pulmonary arterial pressure (PAP) can determine which animals are most at risk for brisket disease, but it only works if the animals are tested at high elevations.


The problem sometimes appears in feedlot cattle, even at low elevations, as these animals get closer to finish weight, because the heart must work harder. These cattle can have the same clinical appearance.


Colorado State University’s (CSU’s) Mark Enns is one of the people doing genetic research.


“We are trying to find ways to know which animals to use in our breeding programs. My role has been to establish a database of PAP scores from CSU animals and a number of cooperators,” he explains. “We’re doing in-house EPD (expected progeny difference) calculations with pedigree information and creating an EPD for pulmonary arterial pressure. This is more accurate for selection purposes than if you just measure bulls and select the ones with the lowest PAP, because the EPD takes in all the bull’s relatives. This can help identify appropriate AI (artificial insemination) sires based on their progeny, PAP, etc."


In population studies, heritability of PAP ranges from 30% to 40%, depending on the population. Enns says this is the same range as yearling weight heritability, so there is certainly a genetic component to PAP.


He adds, “We are trying to figure out ways to deliver more tools to breeders to make good selection decisions. It is especially problematic for AI companies because they are trying to make a living selling semen from bulls. To measure cattle with a PAP test, the bulls have to be at high elevation. Bulls at AI studs come from all over the country, a lot of them from lower elevations,” he says. If someone uses semen from a popular bull on cows at a high elevation, they might end up with a wreck.


“We work with three companies — Select Sires, ABS and Genex — and used some of their semen in our research and then PAP-measured the progeny to begin to get some feel for which bulls might be marketable for semen at higher elevations. We have been doing this for more than 14 years to provide some of the data that contributes to the EPDs, telling us which bulls are acceptable,” says Enns.


Brisket disease is becoming more prevalent.


He explains, “We are hearing more about late-term feedlot death where cattle at finish weight die of heart failure, which is very much like brisket disease. We are trying to establish a link between the low-elevation late-term feedlot death and brisket disease. The more feedlot owners we talk to, the more we realize how prevalent this is becoming, especially at certain times of the year,” he says.


Some cattle may have a genetic tendency for brisket disease, and then with additional factors like hot weather and heavy body weight (more stress on the heart and lungs to service the increased body mass), this may result in heart failure.


Some people hypothesize that during the past several decades, we have selected cattle for faster growth rate and have now exceeded their lung capacity. Enns says it is more noticeable when the cattle are stressed from high elevation, excess body weight with a lot of fat, low oxygen level, etc.


“Our research indicates that it’s not just one gene. This trait is like weaning weight and yearling weight. There are a lot of different genes that influence how fast an animal grows, and there are a lot of genes involved in whether an animal gets brisket disease or not. It’s not a simple thing,” he says.


“If we can get genomic information from animals at birth, at branding, at weaning, or whenever a producer can obtain it, we can plug that into the EPDs so we know which animals we can use in a breeding program. If we can establish the link to late-term feedlot death, then it becomes much more important to the entire beef industry.”

 

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Editor’s Note: Heather Smith Thomas is a cattlewoman and freelance writer from Salmon, Idaho.





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