High ambient temperatures during mating and pregnancy impair sheep reproduction, costing the Australian sheep industry $168 million each year. This collaborative project quantified the benefits for sheep producers of using supplements known to alleviate the impact of heat (eg Melatonin, Vitamin ADE, Vitamin C and Betaine) on flock productivity and thermoregulation. Working alongside 6 farming systems groups and 1 Landscape Board, trials were conducted within 22 producer demonstration sites, using 12,000 ewes.
Melatonin and Vitamin ADE increased potential lambing rate by 19 and 6 percentage units, respectively, which increased the net position of a model flock of 1000 ewes by a $14,019 and $5,296, respectively. Betaine decreased water intake, which is indicative of increased hydration and reduced heat stress, demonstrating potential for use during periods of extreme heat and drought.
Two prototype calculators were also developed. The first, enables producers to predict the impact of Melatonin and Vitamin ADE, and other strategies as they develop, on productivity and profitability of their flocks. The second, enables producers to use climate data for their location to predict the impact of heat events during joining on their lambing rates and, thus, make informed decisions around the adoption of heat alleviating management strategies.
Project description:
The project “Improving the climate resilience of the Australian Sheep Industry” was a collaboration between the University of Adelaide, SARDI, six South Australian farming systems groups, one Landscape Board, and 22 producer demonstration sites. Exposure to high ambient temperatures, in isolation or in combination with high humidity levels, significantly impairs the health, welfare and productivity of sheep, and is common during the periods when ewes are typically mated and pregnant (late spring through early autumn). Each day in excess of 32°C during the week of mating reduces the number of lambs born per 100 ewes mated by 3.5%, with high temperatures during pregnancy retarding fetal growth and, thus, reducing lamb survival and weaning rates. Strategies which increase the capacity of sheep to tolerate heat and mitigate the negative impacts on reproduction are essential to maintain flock productivity and sustainability. It is also important to provide the sheep industry with the ability to predict the impact of heat events on flock productivity and make informed decisions around the adoption of amelioration strategies. In this way, the resilience of the Australian Sheep Industry to extreme and unpredictable climate events will be increased.
With this in mind, the current project demonstrated and quantified the impact of four, easy to implement, strategies for sheep producers to implement to mitigate the impacts of heat events, with the objective of equipping them with the ability to successfully implement these interventions in future years. The strategies were chosen based on ease of implementation and adoption, and their capacity to improve thermoregulation and reduce the physiological stress resulting from heat events. The strategies were Melatonin (delivered as a sub-cutaneous implant, Regulin®), Vitamins ADE (delivered as a long-lasting oral drench), Vitamin C and Betaine (both provided in the water). Alongside of this, the project delivered two prototype calculators which allow sheep producers and industry professionals to make informed decisions around the likely impact of heat events in their region on flock productivity, and quantify the financial impact of adopting the alleviation strategies demonstrated in this project.
Demonstration, validation, and quantification of the impacts of Melatonin or Vitamin ADE on the fertility and fecundity of ewes mated and pregnant during late spring through autumn was achieved in 21 producer demonstration sites across the major sheep producing regions of South Australia, from the South East through to the Upper North and Eyre Peninsula. The impacts of adding Betaine or Vitamin C to the water of ewes during summer on their thermoregulation and water intake was demonstrated at the Roseworthy Trial Site. When analysed across all demonstration sites, Melatonin resulted in an additional 19 potential lambs per 100 ewes mated, and Vitamin ADE increased potential lambing rate by 6 lambs per 100 ewes mated (potential lambing rate is based on the number of fetuses present half way through pregnancy, identified using ultrasound). Betaine supplementation reduced ewe water consumption by 0.66 of litre per day during cooler days (< 32°C) and 1.0 litre per day during hot days (≥ 32°C), and elicited a numerical, but not significant decrease in ewe temperature at the hottest part of the day, indicating a potential increase in the hydration status and heat tolerance of these animals.
Using climate data obtained directly from the producer demonstration sites during mating and early pregnancy, the potential impacts of heat events (days ≥ 32°C) during the week of joining on flock fertility and income were calculated. However, due to the mild nature of the 2022/2023 summer, climate data obtained from the BoM was used to develop the prototype calculators. In partnership with SARDI Climate Applications, historical, region specific climate data (1957 to 2022), cost of production data obtained from the PIRSA Gross Margin Guide, and the quantified impact of Melatonin and Vitamin ADE obtained from the demonstration sites, were used to develop two prototype calculators. Calculator one, provides an easy to use tool for producers and industry professionals to predict the likely incidence of heat events (days ≥ 32°C) during the period of mating, and how the resulting decline in potential lambing rates impacts net income. Calculator two, allows the impact of using Melatonin and / or Vitamin ADE, and other alleviation strategies as they are developed, on lambing rates and income, at a production site specific level. Together, these calculators allow informed decisions to be made around the adoption of strategies to alleviate the impacts of heat.
Key achievements and results:
Overall, the following objectives were achieved:
- Robust, and widely applicable data demonstrating and quantifying the impact of using Melatonin and Vitamin ADE to improve the fertility, and productivity of South Australian sheep flocks which mate between late spring and early autumn.
- Demonstration that adding Betaine to the water supply of ewes over summer has potential to improve thermotolerance
- Development of two prototype calculators which provide the ability at the enterprise level to: 1) predict the impact of heat events on productivity and profitability, and; 2) quantify the impact on productivity and profitability of adopting the heat alleviation strategies developed in this project, and future projects.
This project was designed to increase the climate resilience of the Australian Sheep industry, through demonstration sites and collaboration between producers, farming systems groups and researchers. This approach has ensured effective dissemination and awareness of the project outcomes, as well as the development of outcomes relevant to a wide range of producers.
Further adoption of the outcomes of this project can be supported in the following ways:
- maintain the demonstration sites for at least two more spring / summer periods to obtain additional accurate and robust quantification of the impacts of the current strategies, demonstrate the impacts of new heat alleviating strategies as they are developed and, facilitate producer – producer learning, uptake and, thus, practice change.
- further develop the prototype calculators created in this project to include additional alleviation strategies as they are developed, and also to develop a more widely usable platform for their use (i.e. a webpage or app).
Further information: