Tracking the Heridity of BRD
by Terri Queck-Matzie
According to Iowa State University research published in the Journal of Animal Science, cattle treated one time for Bovine Respiratory Disease (BRD) weighed 24 pounds less at slaughter than healthy cattle, amounting to an average loss of $23.23 per head. With an estimated occurrence rate of more than eight percent, those numbers are staggering when applied industry wide.
That’s
why new research being conducted at Colorado State University is attempting
to identify animals that are genetically more susceptible to BRD.
The preliminary result, according to Dr. Mark Enns, lead researcher for the
project, indicates 19 percent heritability for the animals’ susceptibility
to the disease. “That’s pretty big,” explains Enns. “Birth weight is one
of the most heritable traits and that’s 40 percent. Some breeds of beef cattle
show only about 20 percent heritability for milk production, expressed as
pounds of calf weaned.”
“The goal in this type of study is to determine how
much of the differences in animals’ performance is caused by underlying genetics,”
says Enns, “realizing the possibility of identifying which animals are most
likely to require treatment for BRD could have huge economic consequences
for the beef industry.”
According to Enns, there are many ways producers may choose to use the information
including separation or isolation, drug and nutritional regimes, or implementing
practices such as low-stress weaning and minimal handling.
The BRD project originated with the National Beef Cattle Evaluation Consortium (NBCEC) Scientific Council, which has identified treatment and eradication of disease as an area where genetic improvement can lead to more profit. A team of researchers and graduate students from six different universities was compiled. The project was given industry blessing through the NBCEC and funding was obtained from Pfizer Animal Genetics.
A source for 2,900 steers with traceable pedigrees was found in the Nebraska Sandhills, and the steers were shipped to a feedlot in Lamar, Colorado, adjacent to a Colorado State research facility, an ideal set-up, according to Enns. “We needed the feedyard to process that number of animals and duplicate commercial feedlot conditions,” he explains. “We needed the exposure to disease causing agents and we needed to keep it applicable.” But researchers also needed the time and space to collect detailed disease, immunological and animal data, such as disease exposure and incidence, response to treatment, weight loss, and ultrasound carcass measurements, and immunological and stress status; as well as an assessment of pedigree data. Nearly 40 different measurements were taken and later compared to actual carcass data.
The project’s finding that BRD susceptibility is 19 percent heritable is but the tip of the iceberg, according to Enns. The team is still in the early stages of analyzing data, and the practical application part is yet to come. “We’ve only covered the feedlot side, there’s still the rancher’s perspective,” says Enns. “We will continue to pick apart the genetics for further study and this will spawn many more projects before we’re through. We hope to develop a selection tool that can help both feedyards and ranchers identify these animals.”
Organic and natural producers may choose to simply not handle animals that are identified as susceptible to BRD, and an EPD for BRD susceptibility based on a DNA profile is a tool that holds obvious potential for breeding programs; aside from the changes in feedlot protocols.
“The ultimate goal of this and further projects is to help save producers money and keep animals healthier,” says Enns. ©
easy-to-read articles designed to increase overall awareness among the feedlot community.