Biosecurity Tasmania urges owners of sheep to be vigilant for any signs in their flock of cold stress brought about by forecast cold conditions and heavy rains. Sheep recently shorn and new lambs could be suffering due to the weather conditions and all reasonable precautions should be taken to minimise the effects of cold stress.
Sheep have a natural insulation to extreme weather with their fleece. In cold, wet and windy conditions, sheep shiver, huddle together in the mob and seek shelter behind windbreaks to produce and conserve heat. However, these mechanisms have limits. If weather stress is excessive or prolonged, the sheep's capacity to maintain a stable body temperature may be exceeded and cold stress will result. Hypothermia most commonly occurs in freshly shorn, light condition sheep during wet and windy conditions at any time of the year
Hypothermia literally means 'temperature below normal', occurs when too much body heat is lost or too little body heat is produced, and the result is a drop in body temperature. If weather stress is excessive or prolonged, a sheep's capacity to maintain a stable body temperature may be exceeded, and heat or cold stress will result.
High rainfall and high winds combined with temperatures below normal will cause mortalities in young animals, especially newly shorn sheep without shelter. The impact of the cold weather will depend on its duration, rainfall, wind speed and temperature—the 'wind chill' factor can double heat loss.
Sheep suffering from hypothermia often die as a result of their own behaviour and their attempts to cope. Sheep move in the direction of the wind until they are stopped by a barrier such as a fence, gully or creek. At this point they may pile on top of each other leading to suffocation or drowning. Sheep may be reluctant or unable to move when wet and cold.
Initially sheep will try to maintain their body temperature by:
- shallow breathing in order to reduce the rate of respiration (that is, rapid respiration or panting causes heat loss)
- shivering
- seeking shelter
- huddling together
If dealing with a small flock, consider applying garbage bags as coats for the sheep. Trials have shown that properly fitted plastic bags can decrease the loss of body heat even in severely hypothermic sheep.
Be prepared to relocate animals to a shed or land on higher ground, or move stock to paddocks with adequate windbreaks with tree or bush shelter in the event of very heavy rainfall or likely flooding.
Prioritise your animals, giving shelter to the most vulnerable such as the ewes and lambs and those newly shorn.
The Bureau of Meteorology have issued a flood watch for low lying / flood susceptible areas on Tasmania's east coast, advising graziers that they should prepare to move stock in expectation of heavy rainfall. Visit the BOM website for more information: http://www.bom.gov.au/jsp/watl/rainfall/pme.jsp
More information on caring for your sheep during cold weather can be found on the DPIPWE/Biosecurity Tasmania website: http://dpipwe.tas.gov.au/biosecurity-tasmania/animal-biosecurity/animal-welfare/hobby-farmers-and-smallholders/caring-for-sheep-in-cold-weather
