02 January 2024

Forecasts predict El Niño to continue, resulting in unusually warm and dry summer months across Australia^1,2. As this summer poses an increased risk of extreme heat and heatwaves, it is important to remember that dairy, beef cattle and sheep also feel the effects of hot weather.

Source: bom.gov.au

Heat stress occurs when livestock accumulates more heat than they can lose, creating discomfort and lowering productivity and fertility rates. It is recommended to closely watch your most vulnerable animals, monitor the weather forecast and prepare nutrition strategies for summer to prevent economic losses due to heat stress.

Some common signs of heat stress can include:

• Increase in respiration rate
• Reduced feed intake
• Increased water intake
• Decreased productivity and reproductive rates

Heat Stress & Effects on Cattle

Cattle begin feeling uncomfortable above 25°C³ – which means that heat stress will be an issue across most Australian livestock regions this summer. Not only do extremely high daytime temperatures trigger heat stress, but also hot nights as it is harder to dissipate the heat accumulated during the day, placing livestock under continuous stress. Recent research has revealed that rising air temperatures just 1.5°C above average can decrease cattle conception rates by as much as 5%⁴. Dairy heifers born to cows heat-stressed during late pregnancy have low birth weight and weight gain birth until 12 months of age, have compromised immune function, produce less milk across multiple lactations and have a lower herd survival rate⁵.

Heat stress increases the production of free radicals and reduces the activity of antioxidant enzymes, leading to oxidative stress. In beef cattle and sheep, this can affect meat quality ⁶. In dairy cows, heat stress negatively impacts fertility, milk production and health.  Furthermore, heat stress also affects sperm quality in males ^7,8.

Managing Cattle Heat Stress This Summer

It’s clear that heat stress can result in devastating losses in performance and production – but the good news is that it can be effectively managed. Virbac Australia advises producers to review their preparedness plans for heat stress. This should include an inspection of the livestock environment and infrastructure, shade and water availability, and the addition of fans and sprinklers in intensive production environments.

A summer nutrition program that includes trace mineral supplementation is also key. Heat stress increases the utilisation of trace minerals needed to support fertility, immunity, and the antioxidant system. Multimin is a unique, scientifically proven trace mineral injection containing copper, selenium, zinc and manganese. Multimin is rapidly absorbed, readily utilised and provides sustained antioxidant activity to prepare livestock for high-demand periods such as heat stress ^9-13. Multimin has been demonstrated to help reduce the incidence of metritis and stillbirth and improve the immune function of dairy cows undergoing the transition period under heat stress conditions¹⁴. 

Don’t Delay Heat Stress Management – Now is the Time

A proactive approach to heat stress management is more effective than reactive responses once the damage has occurred. Right now, is a great time to begin implementing the best practices to minimise the impact of what is set to be a hot and wet Australian summer.

For more information about how Multimin can improve the health and performance of your livestock, contact your local Virbac Area Sales Manager or Virbac Customer Support 1800 242 100.

KEY POINTS

• The unusually warm and dry summer forecast across Australia can lead to a potentially dangerous heat load and heat stress in livestock.
• Recent research has revealed that rising air temperatures by as little as just 1.5°C above average can decrease conception rates by as much as 5%³.
• Strategic nutritional programs, including targeted trace mineral supplementation with Multimin, good shade, and access to water sources, can prevent losses to conception, fertility rates, health, meat quality, and milk production.

Find out more

*DISCLAIMER:

The information provided in this article is intended as a guide only. Information contained in this article has been provided by the manufacturer/ You should not rely on the information in this article, and it should not be considered advice. You should seek professional advice regarding relevant factors specific to your situation. This article does not take into account variable conditions that may impact performance. Always read and follow label directions before using any product in this article. To the maximum extent permitted by law, Nutrien Ag Solutions Limited and its related associated entities will not be liable for any loss or damage suffered by any person arising out of any reliance on any information contained in this article.

References

1. The Bureau forecasts an unusually warm summer.https://media.bom.gov.au/releases/1205/the-bureau-forecasts-an-unusually-warm-summer/

Accessed 14/12/2023

1. Rainfall and temperature long-range forecasts. http://www.bom.gov.au/climate/ahead/outlooks/ Acessed 14/12/2023.
2. Collier, R. J., & Collier, J. L. (Eds.). (2012). Environmental physiology of livestock. John Wiley & Sons.
3. Wolfenson D.,Roth Z. (2019), Impact of heat stress on cow reproduction and fertility, Animal Frontiers, 9, (1) 32–38.
4. Dado-Senn, B.et al. (2020). Carry-over effects of late-gestational heat stress on dairy cattle progeny. Theriogenology, 154, 17-23.
5. Gonzalez-Rivas, P. A., et al (2020). Effects of heat stress on animal physiology, metabolism, and meat quality: A review. Meat Science, 162, 108025.
6. Celi P. (2011) Oxidative Stress in Ruminants. In: Mandelker L., Vajdovich P. (eds) Studies on Veterinary Medicine. Oxidative Stress in Applied Basic Research and Clinical Practice. Humana Press, Totowa, NJ.
7. Hansen, P. J. (2009). Effects of heat stress on mammalian reproduction. Philosophical Transactions of the Royal Society B: Biological Sciences, 364(1534), 3341-3350.
8.  Machado, V. S. et al.  (2014). The effect of injectable trace minerals (selenium, copper, zinc, and manganese) on peripheral blood leukocyte activity and serum superoxide dismutase activity of lactating Holstein cows. The Veterinary Journal, 200(2), 299-304.
9. Teixeira, A. G. V.,et al. (2014). Effect of an injectable trace mineral supplement containing selenium, copper, zinc, and manganese on immunity, health, and growth of dairy calves. Journal of dairy science, 97(7), 4216-4226.
10. Mundell, L. et al. (2012). Effects of prepartum and postpartum bolus injections of trace minerals on performance of beef cows and calves grazing native range, Prof. Anim. Sci., 28:82- 88. 7.
11. Swaney, S. (2014). Increasing conception rates in sheep by using an injectable trace mineral product prior to joining in diverse regions across Australia, Virbac data on file.
12. Gonzalez-Rivas, P. A., et al. (2023). A Trace Mineral Injection before Joining and Lambing Increases Marking Percentages and Lamb Weights on Diverse Farms in Victoria, Australia. Animals, 13(1), 178.
13. Silva, T. H.et al. (2022). Effect of injectable trace mineral supplementation on peripheral polymorphonuclear leukocyte function, antioxidant enzymes, health, and performance in dairy cows in semi-arid conditions. Journal of Dairy Science, 105(2), 1649-1660.