Bovine respiratory disease is a complex syndrome accounting for up to 75 percent of the illnesses seen in a feedlot.
Research trials completed earlier this year reclassified the bacteria responsible for shipping fever that costs the beef industry millions in prevention, treatment, decline in animal productivity and deaths.
“About 45 to 55 percent of all mortalities are related to BRD in the feedlot industry,” said Agriculture Canada’s Tim McAlister.
New research uncovered five species of bacteria associated with the disease, but Mannheimia haemolytica predominates. He described the research progress during an animal health session at the Agricultural Biotechnology International Conference in Calgary Sept. 24.
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“It has only been relatively recently that it has been completely reclassified. It used to be called pasteurella haemolytica,” he said.
Smaller studies have been done on this condition but because of the new classification, some may have drawn inaccurate conclusions.
Last October the genomic sequences were released for these bacteria and from there scientists found they could more easily identify the disease.
Using a molecular approach they could identify the disease in about 2½ days at a cost of $4 per sample compared to $20 per sample over four to five days using other tests.
“Compared to the amount of effort that has gone into biochemical tests used previously, this represents a major advance in our ability to study…this disease in the field,” McAlister said.
The disease involves stress factors and can lead to pneumonia. Susceptibility depends on an animal’s health when it arrives at the feedlot and its preweaning care and temperament. A preconditioning program can reduce the incidence of BRD but it is hard to get people to do it, said McAlister.
Multiple stress factors are believed to contribute to an animal developing the disease.
Transportation over long distances may cause exhaustion, starvation, dehydration, chilling and overheating depending on weather conditions. Exposure to vehicle exhaust fumes may worsen the condition.
Additional stressors include passage through auction markets, mingling with strange animals, dusty conditions and processing and surgical procedures on arrival at the feedlot.
Nutritional stress associated with a change to high-energy rations in the feedlot may also sicken young cattle.
When cattle arrive at the feedlot, all may receive an antibiotic treatment as a precautionary measure, or individuals may be treated once they get sick. Antibiotics do not always relieve the BRD problem.
Studies are planned to develop commercially available vaccines.
