​P.PSH.1409-Correlation vs causation - does hydatid disease in cattle decrease carcase weight?

Summary

The prevalence of hydatid cysts in cattle in Australia has been reported to be as high as 33%, resulting in condemnation and downgrading of affected offal.

Previous reports have estimated that the direct loss to a single processor resulting from the condemnation of organs is $6.70. The indirect and productivity losses resulting from hydatids are less well understood, resulting in little incentive for producers to implement control strategies.

This project analysed a dataset of 1,648,049 cattle provided by five processors across eastern Australia to determine the distribution of hydatid disease.

Analysis did not find significant reductions in individual animal carcase weight from hydatids but was able to establish the spatial distribution of hydatid disease in Australia.

Peer review publication

Objectives

The primary objective of the project was to estimate the effect of the presence of hydatid cysts on the carcase weight of cattle to determine the relevance of the disease to producers using processor data. A secondary objective using this data was to describe the occurrence and spatial distribution of hydatid disease in cattle reported by routine meat inspection.

Key findings

Although not all confounding factors could be eliminated, findings suggested that hydatid cysts reduced carcase weight by 0–2.5kg across all years and cohorts of cattle by age.

This translates to small, difficult to observe impacts on liveweight, meaning that although the impact may be significant to industry, there may not be sufficient motivation for producers to undertake greater control measures for hydatid infection.

Mapping of prevalence found a high prevalence of hydatid cysts at processing focused on the Brisbane region, northern New South Wales and regional and coastal Queensland.

Benefits to industry

Understanding the impact that hydatid disease has on the productivity of cattle is important for prevention and control. While the losses incurred due to condemnation and downgrading of viscera are important at an industry level, they are not costs incurred by the producer because producers are not paid for the value of offal from individual animals. Prevention and control of hydatid disease and costs associated with this are incurred at the producer level. Therefore, incentive to adopt control strategies, needs to have benefit for the producer.

MLA action

Given the results of this study, it is unlikely that there will be an incentive for individual producers to invest in hydatid control measures such as vaccines. However, MLA invests across a number of areas that also impact the prevalence of hydatids, including wild dog management.

Future research

Since hydatids only possibly cause a small percentage decrease in liveweight for most cattle, it was suggested that a cost-benefit analysis be conducted to determine the value of a vaccine or other control strategies to producers and processors as next steps.