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preparation and transport and handling of livestock, through to inspection and certification and management during the voyage and after arrival at the destination port.
During the voyage rough seas can lead to traumatic injury, however most cases of lameness develop secondary to injuries and abrasive floor surfaces, with a high risk of secondary
infection due to the presence of progressively contaminated bedding in shipboard pens.
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Lame or injured animals may then become reluctant to stand or move and risk being trampled or not eating or drinking. All of these events increase the risk of other diseases and
of eventual death or euthanasia. Lame or injured animals are reluctant to stand, which increases the risk of their being trampled by pen-mates, and can lead to inappetence and
dehydration.
The recent report by Banney et al
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provides useful advice on cattle selection and bedding management to reduce the incidence of lameness. Further work is required to identify and
implement risk mitigation strategies that may further reduce risk of injury and musculoskeletal conditions. For example, guidelines for optimal deck flooring materials and,
where a bituminised aggregate flooring material is used, optimal aggregate size; and further work on bedding, deck washing and general management of pen flooring for optimal foot
and leg health during the voyage.
12.7 Heat stress
Heat stroke has previously been reported as the most common cause of death in export voyages.
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In contrast, heat stroke was identified as the primary cause of death in only 2 animals in the present study 1 of deaths, although hyperthermia secondary to other disease
processes, for example severe bronchopneumonia and septicaemia, was recorded in an additional 9 animals.
This marked reduction in deaths due to heat stroke is likely to be due to changes that have occurred in the industry since the late 1990s as a result of increased industry awareness of
risk factors for heat stress, and modifications to the selection and management of cattle prior to and during export. In addition, the livestock export vessel fleet has been upgraded, with a
move away from refurbished freight vessels and car carriers to the production of purpose- built livestock carriers. This is supported by examination of mortality rates over the period
1995-2012 based on data from the SMDB.
However, heat stress events do continue to occur from time to time and may be associated with elevated mortalities, as reported in mortality investigation reports available on the
Commonwealth Government website.
Our findings suggest that while improvements in routine practices and ship design and current mitigation measures appear to have reduced the risk of heat stress there is a need
for ongoing effort to continue to use tools such as Hot Stuff and to monitor for and manage heat stress risk during export.
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Banney, Henderson, and Caston 2009
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Hedlefs 1988; Norris et al. 2003
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12.8 Economic costs of major causes of death
Our findings indicate that BRD mortalities in cattle alone are costing the industry more than 0.5 million per year and costs of all mortalities combined in cattle are about 1 million per
year.
We used estimates for morbidity rates and costs associated with BRD treatment and loss of market value that were drawn from recent Australian land-based feedlot studies to inform
assumptions about possible morbidity related costs for export cattle for BRD.
This allowed us to produce an estimate of the total economic impact of BRD on export cattle that included costs due to mortality as well as costs due to morbidity treatment costs and
losses in value in surviving animals. Our estimates indicate that the annual impact of BRD in the population of exported cattle is 1.4 million per year.
If this cost is divided by the total number of cattle exported, it produces a cost per animal exported of 1.63.
The cost per healthy animal loaded provides an economic break-even estimate for risk mitigation measures that are applied to the entire loaded cattle population to prevent the
disease of interest.
However, there are non-economic considerations that may influence a decision to apply a particular intervention, including for example, impacts on public perceptions about the
industry. Such intangible benefits can have major impacts on longer term industry sustainability and may justify industry expenditure on measures that exceed simple cost-
benefit measures.
If preventive measures can be targeted based on risk and applied to a limited and high-risk segment of the export population, then this may achieve much of the benefit reduction in
morbidity and mortality, while avoiding unnecessary costs, because costs are incurred only for some animals and not for all animals.
12.9 Veterinary handbook and related outputs
