Submitted to: Journal of the American Veterinary Medical Association
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/15/2013
Publication Date: 10/1/2013
Publication URL: http://handle.nal.usda.gov/10113/61329
Citation: Richeson, J.T., Pinedo, P.J., Kegley, E.B., Powell, J.G., Gadberry, M.S., Beck, P.A., Falkenberg, S.M. 2013. Association of hematological variables and castration status at the time of arrival at a research facility with the risk of bovine respiratory disease in beef calves. Journal of the American Veterinary Medical Association. 243(7):1035-1041. DOI: 10.2460/javma.243.7.1035. Interpretive Summary: The health management history of newly arrived cattle is typically unknown, a rapid, repeatable, cost-effective method or assay to predict the risk of bovine respiratory disease (BRD) in the production setting could be a valuable aid for refining arrival treatment strategies. A validated marker or technology able to continuously monitor and indicate alterations in behavior or immune response consistent with clinical disease could be used to identify morbid animals. In the current retrospective study complete blood counts upon arrival at the backgrounding facility were utilized to characterize the risk of BRD. Two cell types (Red blood cells and eosinophils) proved to be related to the risk of being treated for BRD. Further investigation is warranted to understand the relationship these cells have with regard to predicting susceptibility of BRD.
Technical Abstract: The objective of this study was to analyze the association between hematological parameters (CBC) and gender at stocker receiving facility arrival and the risk of subsequent clinical bovine respiratory disease (BRD) diagnosis, and (2) to determine and evaluate the accuracy of CBC parameter thresholds on predicting the risk of BRD in newly received beef calves. The retrospective study consisted of 1,179 crossbred bull and steer calves (initial BW = 197 ± 2.4 kg) participating in 4 studies were received at two University of Arkansas cattle facilities and processed according to each specific study protocol. Blood samples were collected at arrival for complete blood count analysis. Calves were subsequently monitored every morning for signs of respiratory illness during a 42-d stocker receiving period and the association between hematological parameters and gender at arrival and the risk of clinical bovine respiratory disease (BRD) diagnosis was evaluated. In addition, the accuracy of CBC parameter thresholds on predicting the risk of BRD in newly received beef calves was examined. The resulting AUC values for the parameters showing significant contrasts were low to moderate, and ranged from 0.51 (neutrophils) to 0.67 (eosinophils), indicating a limited predictive value. The only CBC parameters showing a consistent predictive value for BRD in the multivariable logistic regression analysis were EOS and RBC. The odds of being diagnosed with BRD1 for bulls were 3.32 times the odds for steer cohorts. A combination of reduced EOS and increased RBC levels in peripheral blood could be useful in identifying animals at a higher risk of being subsequently diagnosed with clinical BRD. Results from this study suggest that further research is warranted to investigate and validate the potential use of these measures as predictive biomarkers for BRD. Bull calves at arrival were at a greater risk of subsequent clinical BRD than steers.