Graze paddocks without shade before hot conditions develop.Clean troughs or place additional water points to supply access to clean, cool water for all animals.Plant trees or place shade structures in paddocks.Know which paddocks provide the most shade and better air flow, and move animals early to these paddocks.This proactive approach allows sheep to maintain production. Sheep producers understand the need for forward planning, which can also be applied to heat management.įorward planning allows development of a management strategy to reduce the heat gain by sheep and facilitate heat loss, rather than just responding to heat stress as it is seen in the sheep. If a combination of the factors in the above tables are present, heat stress is more likely. The increase in metabolic heat production during late gestation can predispose ewes to increased heat stress. Lambs are very susceptible to heat stress because of their high metabolic heat production, higher normal respiration rate, large surface area relative to their mass and limited fleece length. In sheep with shorter wool, radiant energy easily passes through to the skin.īreeds originating from cool regions, with compact bodies, short legs and necks, and small ears, are more susceptible to heat stress.

High night-time temperatures prevent loss of heat gained during the day, increasing the risk of heat stress.Īdequate protection from heat is only conferred when the fleece length reaches 30–40mm. Heat stress is increased in calm air conditions because convective heat loss is dramatically decreased. Heat produced by solar radiation can significantly exceed the metabolic heat produced by the animal. Increased humidity reduces an animal’s ability to lose heat through evaporation by panting. Temperatures close to or above the sheep’s body temperature will limit its ability to lose heat via convective cooling. The following tables provide details of climatic and animal factors that may affect an animal’s risk of heat stress. Factors that can influence heat stressĪ complex range of climatic and animal factors influence susceptibility to heat stress. A few simple strategies and guidelines can be followed to reduce the impacts of high temperatures on animals. Managing animals during heat-load events requires proactive planning. Impacts on animal production from heat include reduced conception rates at joining and lower lamb birthweights. Sheep production in pastoral systems is greatly influenced by climatic effects, which can lead to heat stress.

Running sheep danger