Associations between animal characteristic and environmental risk factors and bovine respiratory disease in Australian feedlot cattle

Hay, K. E., Morton, J. M., Mahony, T. J., Clements, A. C. A. and Barnes, T. S. (2016) Associations between animal characteristic and environmental risk factors and bovine respiratory disease in Australian feedlot cattle. Preventive Veterinary Medicine, 125 66-74. doi:10.1016/j.prevetmed.2016.01.013


Author Hay, K. E.
Morton, J. M.
Mahony, T. J.
Clements, A. C. A.
Barnes, T. S.
Title Associations between animal characteristic and environmental risk factors and bovine respiratory disease in Australian feedlot cattle
Journal name Preventive Veterinary Medicine   Check publisher's open access policy
ISSN 0167-5877
1873-1716
Publication date 2016-03-01
Year available 2016
Sub-type Article (original research)
DOI 10.1016/j.prevetmed.2016.01.013
Open Access Status Not Open Access
Volume 125
Start page 66
End page 74
Total pages 9
Place of publication Amsterdam, Netherlands
Publisher Elsevier
Collection year 2017
Language eng
Formatted abstract
A prospective longitudinal study was conducted in a population of Australian feedlot cattle to assess associations between animal characteristic and environmental risk factors and risk of bovine respiratory disease (BRD). Animal characteristics were recorded at induction, when animals were individually identified and enrolled into study cohorts (comprising animals in a feedlot pen). Environmental risk factors included the year and season of induction, source region and feedlot region and summary variables describing weather during the first week of follow-up. In total, 35,131 animals inducted into 170 cohorts within 14 feedlots were included in statistical analyses. Causal diagrams were used to inform model building and multilevel mixed effects logistic regression models were fitted within the Bayesian framework.

Breed, induction weight and season of induction were significantly and strongly associated with risk of BRD. Compared to Angus cattle, Herefords were at markedly increased risk (OR: 2.0, 95% credible interval: 1.5–2.6) and tropically adapted breeds and their crosses were at markedly reduced risk (OR: 0.5, 95% credible interval: 0.3–0.7) of developing BRD. Risk of BRD declined with increased induction weight, with cattle in the heaviest weight category (≥480 kg) at moderately reduced risk compared to cattle weighing <400 kg at induction (OR: 0.6, 95% credible interval: 0.5–0.7). Animals inducted into feedlots during summer (OR: 2.4, 95% credible interval: 1.4–3.8) and autumn (OR: 2.1, 95% credible interval: 1.2–3.2) were at markedly increased risk compared to animals inducted during spring. Knowledge of these risk factors may be useful in predicting BRD risk for incoming groups of cattle in Australian feedlots. This would then provide the opportunity for feedlot managers to tailor management strategies for specific subsets of animals according to predicted BRD risk.
Keyword Bovine respiratory disease
Feedlot
Risk factors
Total effects
Causal diagram
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

 
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