Summer has arrived, and Elders Senior Livestock Production Specialist Rob Inglis has provided this handy guide to managing heat stress in sheep.
If the long-range forecast is to be believed, a large percentage of Australia’s sheep breeding areas will experience above average temperatures this summer. This could affect reproductive performance, particularly for those joining ewes between November and February.
How long does the heat event have to be to cause an impact on reproduction?
The reproductive performance of the ewe is most affected by heat stress in the week prior to oestrus, during oestrus and then for the ensuing 5 days.
For rams, relatively short periods of high temperatures (1 to 4 days) can have a negative impact.
However, there is significant variation between rams and ewes in their response to heat stress.
What are the impacts of heat stress that will affect reproductive efficiency?
- Decreased appetite.
- Increased metabolic rate and decreased antioxidant production.
- Decreased quality (and often quantity) of sperm production.
- An increase in production of stress hormones.
- A decrease in mating activity. This may ultimately lead to a protracted lambing.
- Detrimental impacts on the ewe’s ovum and eggs, embryo survival, and the placenta.
- Lower birth weights leading to an increase in lamb mortality.
- A decrease in milk production.
This graphic shows some of the impacts of sustained exposure to high temperatures for ewes. Source: The Sheep Reproductive Strategic Partnership – MLA.
Strategies to avoid heat stress
- 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.
- Maximise shade and water for ewes at joining and in late gestation, and for stock under 1 year old. These animals are particularly vulnerable to heat stress.
- Administer antioxidant supplements, for example, Multimin Chrome, Beachport Whitecap, and vitamins A, D and E.
- Provide high quality, low fibre (NDF) feed such as good quality silage or grain.
Speak to an Elders Livestock Production Advisor for further information.
Disclaimer - important, please read:
The information contained in this article is given for general information purposes only, current at the time of first publication, and does not constitute professional advice. The article has been independently created by a human author using some degree of creativity through consultation with various third-party sources. Third party information has been sourced from means which Elders consider to be reliable. However, Elders has not independently verified the information and cannot guarantee its accuracy. Links or references to third party sources are provided for convenience only and do not constitute endorsement of material by third parties or any associated product or service offering. While Elders has exercised reasonable care, skill and diligence in preparation of this article, many factors including environmental/seasonal factors and market conditions can impact its accuracy and currency. The information should not be relied upon under any circumstances and, to the extent permitted by law, Elders disclaim liability for any loss or damage arising out of any reliance upon the information contained in this article. If you would like to speak to someone for tailored advice specific to your circumstances relating to any of the matters referred to in this article, please contact Elders.
