Abstract
Bovine respiratory disease (BRD) is the most prevalent disease in feedlot cattle worldwide with Bovine alphaherpesvirus 1 (BoAHV1), Histophilus somni, Mannheimia haemolytica, Mycoplasma bovis, Pasteurella multocida and Trueperella pyogenes accepted to be common etiological agents associated with BRD. Whilst these agents are common in the upper and lower airways in clinical BRD cases, some also exist as normal flora suggesting their presence in the upper airways alone is not necessarily informative with respect to disease status or risk.
To determine the relationship between potential BRD pathogen presence, load and disease status, we investigated the correlation between load in the upper airways at induction and active BRD cases in feedlot cattle using efficiency-corrected (EC) PCR quantification. By this approach, we were able to accurately determine the prevalence and load of the key BRD agents in the upper respiratory tract showing that cattle in the hospital pen had a higher prevalence, and load, of these agents both singly and in combination compared to cattle sampled at feedlot induction.
Bayesian Network modelling indicated that the combination of agents and location was the most accurate indicator of BRD risk with cattle with four or more agents detected in the upper airway more likely to be treated during their time on feed, and more likely to be treated for BRD than nonBRD ailments. In addition, M. bovis was rarely detected at feedlot induction but was identified at high prevalence in cattle in the hospital pen. This study is the first to report on the practical application of efficiency-corrected quantification to determine accurate pathogen load of BRD associated organisms in the upper airways.
Review of this data suggests that the optimal pathogen panel for detection of animals suffering from, or at risk of developing BRD, should include Bovine herpesvirus 1, Bovine Corona Virus, Bovine Parainfluenza Virus 3, Bovine respiratory Syncytial Virus, H. somni, M. haemolytica, M. bovis, P. multocida, and T. pyogenes. These findings present a potential new technological approach for the investigation, analysis and identification of BRD-associated viral and bacterial agents for Australian feedlot systems as well as for BRD disease management and treatment.
Finally, to determine the cost benefit of integration of a microorganism testing platform into feedlot management practices, a growth / intervention model was developed using data collected from four sites in 2021. The initial assumptions and grid frameworks are presented in this report.
To determine the relationship between potential BRD pathogen presence, load and disease status, we investigated the correlation between load in the upper airways at induction and active BRD cases in feedlot cattle using efficiency-corrected (EC) PCR quantification. By this approach, we were able to accurately determine the prevalence and load of the key BRD agents in the upper respiratory tract showing that cattle in the hospital pen had a higher prevalence, and load, of these agents both singly and in combination compared to cattle sampled at feedlot induction.
Bayesian Network modelling indicated that the combination of agents and location was the most accurate indicator of BRD risk with cattle with four or more agents detected in the upper airway more likely to be treated during their time on feed, and more likely to be treated for BRD than nonBRD ailments. In addition, M. bovis was rarely detected at feedlot induction but was identified at high prevalence in cattle in the hospital pen. This study is the first to report on the practical application of efficiency-corrected quantification to determine accurate pathogen load of BRD associated organisms in the upper airways.
Review of this data suggests that the optimal pathogen panel for detection of animals suffering from, or at risk of developing BRD, should include Bovine herpesvirus 1, Bovine Corona Virus, Bovine Parainfluenza Virus 3, Bovine respiratory Syncytial Virus, H. somni, M. haemolytica, M. bovis, P. multocida, and T. pyogenes. These findings present a potential new technological approach for the investigation, analysis and identification of BRD-associated viral and bacterial agents for Australian feedlot systems as well as for BRD disease management and treatment.
Finally, to determine the cost benefit of integration of a microorganism testing platform into feedlot management practices, a growth / intervention model was developed using data collected from four sites in 2021. The initial assumptions and grid frameworks are presented in this report.
| Original language | English |
|---|---|
| Place of Publication | North Sydney, NSW |
| Publisher | Meat and Livestock Australia Ltd |
| Commissioning body | Meat and Livestock Australia |
| Number of pages | 99 |
| Publication status | Published - 08 Jun 2023 |
