Sheep and Heat Stress: The Facts

Sheep and Heat Stress: The Facts

The Australian Veterinary Association and the Federal Government commissioned review of the live sheep export industry by Dr Michael McCarthy raised the issue of the impact of heat stress on sheep.

The AVA provided a detailed submission to the McCarthy Review based on the most up to date animal science. The AVA said:

“Irrespective of space allocation, thermoregulatory physiology indicates that sheep on live export voyages to the Middle East during May to October will remain susceptible to heat stress and die due to the expected extreme climatic conditions. Accordingly, voyages carrying live sheep to the Middle East during May to October cannot be recommended.” 

Thermoregulation is the process by which a sheep maintains its core internal body temperature. When high humidity is combined with high air and sea temperatures which do not drop overnight, sheep can no longer regulate their core body temperature. As a result, they start to show open-mouthed panting followed by dehydration, overheating of body organs and a slow painful death. The risk of encountering this extreme temperature and humidity combination in the Middle East increases during May to October, with a significant peak in August.

Dr McCarthy recognised that voyages during May to October would likely continue to pose a great risk to sheep welfare. In his report to the Federal Government, in Recommendation 4 he said there should be a revision of the way in which the risk of heat stress was calculated, to be introduced by 1 July, moving from one based on mortality, to one based on indicators of heat stress. Dr McCarthy indicated that, based on current vessel ventilation data, this revision would require a further significant reduction in stocking density which should be implemented by 1 July this year.

However, the reduction of the number of sheep on each ship arising from this recommendation would have meant voyages would no longer be profitable for the export companies. It would therefore have effectively ended the summer trade to the Middle East. This is why Recommendation 4 was rejected by the Federal Government.

This resistance by the Federal Government to change is a disservice to sheep farmers. The continuation of Middle Eastern summer voyages will only ensure more instances of sheep suffering and dying of heat stress and the inevitable public backlash which will simply hasten the demise of the live sheep trade. 

It is very clear from the Federal Government’s approach that the live sheep trade to the Middle East is built on a business model in which animals must suffer for the exporters to profit.


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