Shelter and hypothermia in sheep
Australia’s weather extremes are brutal and millions of sheep and lambs are at its mercy. Although sheep have natural insulation to extremes of cold weather with their fleece, if weather stress is excessive or prolonged, sheep’s capacity to maintain a stable body temperature may be exceeded and cold stress will result.
In sheep farming areas of Victoria, it is a common sight to see recently shorn sheep, on cold winter days, with little or no shelter from the extremes of temperatures. Sheep are prone to hypothermia, with high mortalities occurring in mobs for up to four weeks after shearing.
“Sheep should be provided with shelter in above and below averages temperatures” 
– Agriculture Victoria
Recently shorn sheep with no shelter, Western Victoria 30 June 2020. Weather conditions: consistent rain 0-15 degrees celcius
Photo credit: Gary Hall
Young animals are more susceptible to hypothermia, as they have less fat reserves to mobilise. It is estimated up to 15 millions lambs die every winter in Australia in the first 48 hours, with one of the main causes being exposure to the cold.
“Hypothermia, which 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.” 
Joining and birth
Despite ewes’ fertility peaking between March and May in Victoria and them having a 5 month gestation period, farmers join ewes earlier, resulting in sheep giving birth in the cold, harsh winter. Farmers desire winter lambing, so as by the time lambs are weaned, spring grass is growing, which saves money, by not needing to supplement sheep’s food. Plus, there is a demand for spring lamb.
Sheep are selectively bred to have a greater number of lambs. Multiple births often result in the rejection by ewes of at least one lamb. These lambs cannot survive without the care of their mother so die as a result of hypothermia, exposure or death by a predature. Despite the huge numbers of deaths, it is still more profitable for farmers to breed for multiple births than single ones.
Sheep are undeniably adversely affected by the extremes of temperatures in Australia. Countless sheep and millions of lambs die every year, due largely to the extremes of low temperatures. Melbourne Sheep Save believes that the guidelines for shelter listed on the Agriculture Victoria website should be made a legal requirement on all farms, instead of a recommendation.