It’s not only a significant animal health problem for U.S. cattle producers, but bovine respiratory disease (BRD) is the most common infectious disease in cattle worldwide, says Holly Neibergs, a University of Washington geneticist. And in spite of intensive efforts to prevent and treat the cattle disease, respiratory problems still challenge cattlemen.
“If we look at a 15-year average, we see the national prevalence of this disease is about 16% in feedlots over 1,000 head,” she says. “And unfortunately, it doesn’t seem like anybody is really spared. Over 97% of feedlots over 1,000 head said they had BRD as an issue in their lot.”
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The research is part of the Bovine Respiratory Disease Complex Coordinated Agricultural Project, a nationwide, multi-university undertaking to find solutions to BRD. The 1,000-head research project is the first leg in a multi-year research effort that will ultimately involve around 3,000 head.
Looking at the cattle that got sick in the research trial, Neibergs says the total economic loss, including death loss, treatment cost and lost carcass value, came to around $254/head. “So with the estimated rate of genetic gain of selecting for BRD resistance, we could have saved between $80 million and $132 million if we would have selected for enhanced BRD resistance,” she says.
And she says that’s probably understated. In a research project that looked at almost 1,000 steers in a commercial feedyard, she says that 67% of the animals diagnosed with BRD had lung lesions and 67% of the cattle that were considered healthy also had lung lesions. That means, she says, that a lot of the “healthy” cattle had subclinical respiratory disease issues.
However, she says there is some evidence, based on research done at the U.S. Meat Animal Research Center and elsewhere, that BRD has some genetic underfooting. Based on her research, she says the heritability of BRD susceptibility could range between 18% and 29%.
So far, genetic research on BRD has identified some gene loci. That work is ongoing and researchers are drilling down to find the underlying genetic causes.
Once the genetic connection is more fully understood, Neibergs says that information can be used as cattlemen make their genetic selection decisions. And if the heritability estimates hold true, it’s possible that the number of BRD cases can be whittled down.
“If you think about a heritability somewhere around 20%, that’s not bad,” she says. “Selection for dystocia (calving difficulty) has been pretty effective and it has about the same heritability.”
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