Associations between prior management of cattle and risk of bovine respiratory disease in feedlot cattle.
Bovine respiratory disease (BRD) is the major cause of clinical disease and death in feedlot populations worldwide. A longitudinal study was conducted to assess associations between risk factors related to on-farm management prior to transport to the feedlot and risk of BRD in a population of feedlot beef cattle sourced from throughout the cattle producing regions of Australia. Exposure variables were derived from questionnaire data provided by farmers supplying cattle (N=10,721) that were a subset of the population included in a nationwide prospective study investigating numerous putative risk factors for BRD. Causal diagrams were used to inform model building to allow estimation of effects of interest. Multilevel mixed effects logistic regression models were fitted within the Bayesian framework. Animals that were yard weaned were at reduced risk (OR: 0.7, 95% credible interval: 0.5-1.0) of BRD at the feedlot compared to animals immediately returned to pasture after weaning. Animals that had previously been fed grain (OR: 0.6, 95% credible interval: 0.3-1.1) were probably at reduced risk of BRD at the feedlot compared to animals not previously fed grain. Animals that received prior vaccinations against Bovine viral diarrhoea virus 1 (OR: 0.8, 95% credible interval: 0.5-1.1) or Mannheimia haemolytica (OR: 0.8, 95% credible interval: 0.6-1.0) were also probably at reduced risk compared to non-vaccinated animals. The results of this study confirm that on-farm management before feedlot entry can alter risk of BRD after beef cattle enter feedlots.
The University of Queensland, Queensland Alliance for Agriculture and Food Innovation, St Lucia 4072, Queensland, Australia.
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KE
Hay
The University of Queensland, School of Veterinary Science, Gatton 4343, Queensland, Australia; Jemora Pty Ltd., P.O. Box 2277, Geelong 3220, Victoria, Australia.
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JM
Morton
The University of Queensland, Queensland Alliance for Agriculture and Food Innovation, St Lucia 4072, Queensland, Australia.
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ML
Schibrowski
The University of Queensland, Infectious Disease Epidemiology Unit, School of Population Health, Herston 4006, Queensland, Australia.
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Clements
The University of Queensland, Queensland Alliance for Agriculture and Food Innovation, St Lucia 4072, Queensland, Australia. Electronic address: t.mahony@uq.edu.au.
T J
TJ
Mahony
The University of Queensland, Queensland Alliance for Agriculture and Food Innovation, St Lucia 4072, Queensland, Australia; The University of Queensland, School of Veterinary Science, Gatton 4343, Queensland, Australia.
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TS
Barnes
D000822:Animal Husbandry / Q000379:methods*; D000818:Animals; D001315:Australia / Q000453:epidemiology; D048090:Bovine Respiratory Disease Complex / Q000453:epidemiology* / Q000209:etiology; D002417:Cattle; D016015:Logistic Models; D008137:Longitudinal Studies; D011446:Prospective Studies; D012307:Risk Factors
Bovine respiratory disease; Feedlot cattle; Longitudinal study; Risk factors; Vaccination; Yard weaning