Characterizing BRD Sickness Response
If BRD sickness response is more understood, cattle can be treated faster.
Bovine respiratory disease (BRD) is a big deal from both a health and an economic perspective. Animal behavior is being researched to help diagnose the disease more quickly. University of California–Davis graduate student Rachel Toaff-Rosenstein explained that her study “thinks outside the bottle” on BRD diagnosis to attendees of the 2014 International Symposium on Beef Cattle Welfare in Ames, Iowa, July 16-18.
Treatment for BRD hinges on diagnosis accuracy so it can be given in a timely manner, especially with increasing opposition to antibiotic use. Four symptoms, called DART — depression, appetite loss, respiratory changes and temperature elevation — are the main cues to diagnosing BRD in cattle, though sensitivity and specificity are only 62% and 63%, respectively. There is much room for improvement, she noted.
DART symptoms are only part of the BRD sickness response. Inflammation leads to the sickness response, which includes increased lethargy, pain sensitivity, immune activity, fever; and decreased appetite, social interaction and grooming.
Her study asked whether diagnosis could be improved with continuous monitoring with technology. Rumen boluses noticed fever, but at more than $50 each, they proved to be cost-prohibitive. Feed efficiency equipment, like the GrowSafe model, measures bunk attendance and feed intake. This did indicate sick calves four days before the pen rider, but it is also very expensive. There isn’t much research in grooming response.
In her challenge model, 40 steers were divided into two groups. One group was given viral and bacterial challenges and the other group was used as the control. She calculated the clinical sum score, which is the composite score to describe the clinical severity, and performed necropsies on the challenged steers. Results showed that the relationship between the clinical sum score and the number of lung lesions was not straightforward. A higher rectal temperature was observed, but not lung lesions. She granted that may have been on account of heat stress.
“There was a significant correlation between severe lung lesions and decreased bunk attendance,” Toaff-Rosenstein reported.
There was no relationship between brush use (to observe grooming behavior) and clinical illness, though she did observe less brush use in steers with more lung lesions.
