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The above table is suggestive of the potential for different mortality risk for sheep raised within New South Wales, in that sheep from the southern districts Balranald, Hillston, Wentworth may have
different risks compared with sheep raised in districts that are further north or west. This raises the question of whether the use of a broad classification system such as the sheep production zones to
determine whether sheep may or may not be prepared for export, may be discriminatory and subject some sheep to unfair exclusion from export.
There appears to be little research further investigating associations between pastoral sheep in Western Australia and South Australia and the risk of morbidity and mortality during export.
Several studies have now documented what appears to be an association between lines of sheep and mortality risk that suggests that some properties or areas may have characteristics that result in
repeatedly higher risk of mortality Norris et al., 1989a, Higgs et al., 1999, Makin et al., 2009. There is also evidence that the term pastoral sheep may include some geographic areas associated with
higher mortality risk and other geographic areas that are not associated with higher mortality risk Makin, 2010.
There is an opportunity as traceability improves in the sheep export supply chain in association with ESCAS, to conduct research to develop methods for tracking mortality risk to line of origin on routine
export voyages. This information could be used to identify properties with high and low mortality risk and to better understand the driving factors that may influence this risk as well as providing a direct
opportunity to act on this information by avoiding sheep from properties or areas with demonstrated higher mortality risk.
There is a need to conduct additional research to investigate the broader issue of classifying sheep based on origin pastoral or otherwise and using this classification to define suitability for the export
supply chain. The term pastoral sheep appears to be a broad and relatively non-specific classification.
6.7 Paddock vs
shed
Standard 3.9 differentiates between sheep held in paddocks and sheep held in sheds. Several of the registered premises in Western Australia have elevated sheds with mesh flooring to
allow faeces and urine to drop through the floor and collect underneath the building. Sheds offer advantages over paddocks including protection from weather, elimination of soil erosion and dust,
and improved facilities for sheep handling and general management Norris et al., 1989b. Shedded sheep are believed to have decreased risk of salmonellosis because of reduced exposure to
environmental contamination and protection from the potentially stressful effects of adverse climatic conditions that may reduce host resistance More, 2002a. Preparation of sheep in sheds is
identified as a management strategy for reducing or eliminating outbreaks of salmonellosis More, 2002a.
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A more detailed discussion of the potential advantages and disadvantages of sheds has been provided by More 2002b, including consideration of cost-benefit issues. It appears highly likely that
shedding would reduce risk of salmonellosis in sheep during preparation for export, and would therefore have a beneficial impact on mortalities in export sheep throughout the supply chain.
However, a more detailed review of all feasible options and potential impacts for control and prevention of salmonellosis should be conducted before any decision should be made to require
shedding in all registered premises
6.8 Age of sheep
Standard 3.9 prohibits preparation of lambs held in paddocks for export between May-October. There appears to be variable evidence for increased mortality risk in lambs no permanent incisors
that may justify exclusion of lambs from export to the Middle East during the period from May-October. Monthly mortality estimates are produced for various age classes of sheep covering
the period from 1997-2009 Norris and Norman, 2010. These figures indicate that adult wethers have a higher mortality risk than hoggets and lambs throughout the May-October period, and that
mortality in wether lambs may be higher than in hoggets for some of the months in the risk period and not different in other months. A similar pattern is shown for rams adult vs hogget vs lamb and
for ewes adult vs lamb Norris and Norman, 2010. The findings do provide sufficient evidence for elevation in mortality risk in lambs in at least part of the risk period and therefore there seems to be
rationale for exclusion of lambs from export during the May-October period. It should be noted that should further research identify explanatory factors for this apparent difference in risk that can be
effectively managed then these restrictions may warrant revisiting.
6.9 Transport distance
