Heat Stress in Dairy Cattle: What You Need to Know

Summer is starting to warm at last and while many enjoy the sunshine, for farmers, it means rolling up our sleeves and knuckling down through the busiest time of year. With the sunshine comes a challenge: dairy cow heat stress and when the mercury climbs above 22°C, milk productivity starts to drop. 

How we handle the heat can make a big difference, not just on our summer milk cheques, but on our performance for the rest of the year. With some practical solutions, we can ensure our cows stay happy and healthy, even when the mercury’s rising.

Understanding How Dairy Cows Allocate Energy

In a healthy cow, available energy is allocated to bodily processes in a specific order of priority. First and foremost, energy is directed towards maintenance – keeping the cow’s basic functions running smoothly. Once maintenance needs are met, energy is allocated to  growth followed by milk production, reproduction and immunity. 

When cows don’t get enough energy or experience health problems, this upsets her energy balance and her overall performance. For example, if a cow has a difficult calving and struggles to clean properly, a significant portion of her energy goes to recovery. This leaves less energy for milk production, often resulting in a poorer start to lactation.

Reduced availability of energy can impact other aspects of cow performance, including growth, fertility, and immunity. 

Dairy Cow Heat Stress

In warmer weather conditions when dairy cows aren’t able to cool down effectively, this is known as heat stress. Every animal has a comfortable temperature range where it doesn’t need to use extra energy to stay warm or cool. For cows, this range is between -10 and 22 degrees Celsius (Kempenaar & Van Dooren, 2003).

Due to their high heat production and feed intake, lactating dairy cows are much more susceptible to heat stress than youngstock and beef. Fresh cows, high-producing cows and dry cows are also considered high-risk, due to the already high energy demands on their bodies.

When a cow is dealing with heat stress, she tends to eat less, even though she really needs extra energy and protein to maintain her health and productivity. Even at temperatures as low as 20°C, dairy cows can show reduced feed intake of 10% or more. Consequently, you see that milk production can start to drop by 15 to even 40%.

What is your Heat Stress Protocol?

Supporting your herd’s energy balance is key to avoiding a drop in productivity and performance. Here are some key steps you can take once you see a heatwave forecasted.

1. Support your herd in maintaining a positive energy balance
   Add AHV Booster Powder twice daily as top dress to your herd ration to support all lactating cows in the lead up to and throughout the warm weather period. With just 100 grams per cow,
   
   AHV Booster Powder provides an energy boost and stimulates your cows appetite and energy utilisation, helping her to maintain normal eating and production patterns. AHV Booster Powder activates their metabolism, especially in the liver and rumen and is an easy addition to your normal routine.
2. Extra support your high-producing cows
   For extra support, particularly for high-producing cows, dry cows, older cows or those at higher risk, we recommend providing a Booster Tablet the day before hot weather sets in. This encourages increased eating and sustains energy levels during challenging conditions.
   
   The AHV Booster Tablet activates their metabolism, especially in the liver and rumen helping her to utilise more energy from her feed. This supports a positive energy balance helping her to maintain production and overall health.

Consider the following support measures as part of your dairy cow heat stress strategy;

• Manage Grazing Patterns: Choose fresh pasture with adequate shade and access to water and avoid grazing during the hottest parts of the day.
• Access to Water: Ensure constant access to clean, fresh water. Increase the number of water sources and check them regularly to ensure they are not running low or contaminated. 
• Ensure Adequate Indoor Ventilation: Open windows and doors for natural ventilation for indoor housing and install fans or ventilation systems to maintain airflow. 
• Adjust Feeding Practices: Feed cows during cooler times of the day and provide high-quality, easily digestible feed to reduce metabolic heat.
• Sprinkler Systems and Cooling: Install sprinkler systems, misters or in housing facilities to provide a cooling effect. 
• Reduce Workload: Minimise handling and moving of cows during hot weather to reduce stress.

Monitor Cows Regularly and Respond Quickly to Signs of Stress

Even with these measures in place it’s important to keep a close eye on cow behaviour and signs of heat stress, such as increased panting, drooling, signs of agitation, reduced feed intake, and decreased milk production. 

If the cow is already showing signs of heat stress, AHV Booster Powder can be given as a drench to provide immediate energy support and rehydrate the cow fast. Simply mix 1 kilogram of Booster Powder with 20 litres of lukewarm water. Watch our video to learn how to safely drench pump your cow.

If drenching isn’t possible, you can alternatively give the cow two Booster Pastes.

Being proactive in supporting your herd during heat stress can make a big difference in their health and productivity. By providing them with the extra energy they need, we can help them stay healthy and comfortable, even when the heat is on.

Want to learn more? Check out the results from our UK Booster Tablet Trials.

Sources

Aggarwal, A., & Upadhyay, R. (2013). Heat stress and animal productivity (Vol. 188). Delhi, India:: Springer.

Kempenaar, C., & van Dooren, H. J. C. (2003). Geen koudestress op lagekostenbedrijf. Praktijkkompas. Rundvee, 17(4), 32-33.

Van Laer, E., C. P. H. Moons, B. Ampe, B. Sonck, L. Vandaele, S. De Campeneere, en F. A. M. Tuyttens. 2015a. Effect of summer conditions and shade on behavioural indicators of thermal discomfort in Holstein dairy and Belgian Blue beef cattle on pasture. Animal 9 (9):1536-1546. doi 10.1017/s1751731115000804