1 Introduction
1.1 Background
High mortality incidents in livestock export to the Middle East over the 2002 northern summer have highlighted systemic weaknesses in the standards and procedures previously
applied to animal welfare and mortality risk reduction on such voyages. There has been a need to bring practices into line with the current risk management knowledge which has
been documented particularly over the last two years. From work for LiveCorpMLA by Dr Richard Norris of AgWA, it is known that the three
principal causes of mortality in sheep and goats are inanition failure to eat, feedlot related salmonellosis and heat stroke. Inanition causes weaknesses which predispose the animal to
other diseases including salmonellosis and is characterised by a trickle of mortality which, if anything, builds slightly towards the end of long haul voyages. Feedlot related salmonellosis
is evidenced by scour, and mortalities generally peak within the first 5 days of a voyage and subside to inanition type levels later in the voyage, when the two diseases are often likely to
be in combination anyway. When either of these problems is very severe, the combination of the two may push the mortality rate above the 2 reporting threshold.
Heat stroke, and the precursor heat stress, occurs as sudden deck-wide epidemics when the environmental conditions are such that animals cannot reject sufficient heat to maintain core
body temperature at normal levels in the face of the ongoing generation of internal body metabolic heat. Before a major epidemic becomes apparent, increasing environmental
heat will drive up mortality rates as those sheep weakened by salmonellosis or other diseases succumb before the general population. Oddly, some degree of inanition may
assist survival in a heat wave by decreasing the animals’ internal heat generation. This is not yet certain.
For cattle, the principal causes of mortality are trauma, respiratory disease and heat stroke. Trauma is minimised through animal housing design and handling procedures. Respiratory
disease prevention is the subject of a current LiveCorpMLA study led by Dr Simon More. Heat stroke and heat stress in cattle follow epidemiological patterns similar to those for
sheep, albeit with onset over a wide range of conditions for different livestock types and lines.
Studies coordinated by LiveCorp and MLA and managed principally by Dr Conrad Stacey of Maunsell Australia and Dr Simon More of AusVet Animal Health Services have elucidated
and documented the science relating to the heat stress, ventilation and salmonellosis issues relevant to livestock export by sea.
1.2 Scope and Objectives
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