P.PSH.0873 - Monitoring health and welfare using emerging diagnostic technologies in the beef feedlot sector

Summary

Bovine respiratory disease (BRD) represents one of the largest animal health costs to the Australian feedlot industry. BRD incurs costs to the industry related to loss of production due to poor performance and/or death, time taken in management of sick cattle in the hospital system, cost of treatments, and reputational costs to the industry related to disease burden in intensive systems. This project developed some new tools that are available to industry to help manage and minimise risk of BRD in cattle.

Objectives

The objectives of this project were to:
• determine the pathognomonic profile of BRD in a sample of Australian feedlots
• develop a rapid, scalable diagnostic testing platform that could be used to test within and between animals and cohorts and locations
• to define an optimal agent test panel for the identification of BRD disease risk in Australian feedlot cattle.

Key findings

Results showed that cattle diagnosed with more than three infectious agents at induction and cattle in the hospital system were more likely to be treated for BRD than other disorders. For the pathogen Mycoplasma bovis, very low numbers of cattle tested positive at induction, but high proportions tested positive after 14 days on feed and in the hospital system. Bayesian Network modelling identified the number and combination of agents, distance travelled to feedlot and feedlot location to be the primary drivers of disease outcome by this analysis. Bio-economic analysis determined that even at a relatively low predictive accuracy of 34%, the use of a risk-based test and treat strategy was profitable for feedlot cohorts with a higher proportion of high-risk animals (as classified by PCR), e.g. saleyard purchases. However, a risk-based test and treat strategy was not profitable when cohorts had a low risk profile (<15% of animals classified as low risk), as was the case for direct paddock purchased cohorts.

Benefits to industry

Bio-economic analysis determined that even at a relatively low predictive accuracy of 34%, the use of a risk-based test and treat strategy was profitable for feedlot cohorts with a higher proportion of high-risk animals (as classified
by PCR), e.g. saleyard purchases. However, a risk-based test and treat strategy was not profitable when cohorts had a low risk profile (<15% of animals classified as low risk), as was the case for direct paddock purchased cohorts. In feedlot intakes with high BRD risk by our measure (e.g. saleyard purchases), modelling of a risk-based treatment for BRD was found to increase profitability by $5.44–$8.60 per head, while also improving animal welfare outcomes by treating animals identified to be sub-clinical (based on visual assessment).

MLA action

The results of this project will be shared with the Australian Lot Feeding Industry and MLA will continue to invest in preventive measures for Bovine Respiratory Disease.

Future research

Further objective epidemiological testing and data collection should occur at additional sites across
Australia, including in northern Australian feedlot systems, to examine BRD-casing agent profiles across the industry to correlate to disease incidence in different management systems, and to confirm the risk stratification identified in this report in a larger sample.

Further analysis needs to be undertaken to determine the role of M. bovis as a key opportunistic pathogen in Australian feedlot systems and to investigate the efficacy of vaccine interventions for this opportunistic pathogen.

Further investigation is required into the role and impact of Bovine Herpes Virus-1 in the prevalence of BRD in Australian feedlot systems.

The diagnostic test developed as part of this project should proceed to development of a commercially available kit or publication of the assays in the peer-review literature to allow widespread availability to industry either for location-specific profiling or individual animal diagnosis.