Genetic Testing for Bovine Respiratory Disease
Research project is looking for genetic resistance to BRD
that could help reduce antibiotic use.
Bovine respiratory disease (BRD), also called pneumonia or shipping fever, is the most costly disease in the U.S. cattle industry, particularly in the feedlot sector. More than 1 million animals are lost each year for a financial loss of more than $700 million. Now that genetic research has given us tools to select for and against certain traits in cattle, researchers are looking into genetic approaches to select for cattle that are less susceptible to disease.
Several groups are working together on the BRDC (Bovine Respiratory Disease Complex) Coordinated Agricultural Project (CAP) with a USDA grant through the National Research Initiative. This project involves researchers at Texas A&M, Washington State University, the University of California–Davis, New Mexico State University, Colorado State University, the Agricultural Research Service (ARS) and GeneSeek.
The researchers have already looked at 2,000 dairy calves (half of them BRD cases and half as controls) and are now studying 2,000 feedlot beef animals (BRD cases and controls) to determine if there are differences in genetics, genotyping them with a high-density SNP chip. The next step is validating those findings by using genotypes from an additional 1,000 dairy and 1,000 beef case/control animals from different geographic locations, to make sure the findings are accurate. This research may lead to genetic tests that could identify animals that are resistant or susceptible to BRD.
Jim Womack, Texas A&M, is the project director, and his group is analyzing data. He says the genetic differences will be useful to producers in the future to help select animals based on their resistance.
“Eventually this will lead to discovery of the genes themselves that are responsible,” he says. “This could suggest new vaccines, new diagnostics, new treatments, etc., that could be utilized to reduce BRD.”
This is an exciting new field and may help explain some of the things breeders have wondered about, regarding the tendency for certain animals to be hardier and more disease-resistant than others. There may be some breed differences, or variations within a breed when comparing certain bloodlines, and probably some differences in comparing crossbred animals with purebreds. Heterosis tends to boost hardiness and decrease susceptibility to disease.
“These studies will help us get a little closer to the reasons. We’ve known for a long time that there was some heritability to disease resistance, but it’s been hard to get a finger on where and what the genes are,” says Womack.
“As we get farther along with our knowledge, we may not need to use as many antibiotics in food animals. This is one of our goals.”
Editor’s Note: Heather Smith Thomas is a freelance writer and cattlewoman from Salmon, Idaho.