The days are getting longer, and the summer heat will be here before you know it. As the days get warmer, we know that controlling the negative impacts caused by heat stress is a concern for dairy producers, but did you know that heat stress can also lead to other production issues that may not appear until the fall?
Every dairy cow has a threshold within which it will be able to perform its normal body functions and behave normally. When the environment is too hot and they start to experience heat stress (Temperature-Humidity Index above 68), the cow will start to modify its behavior to dissipate the extra heat.
For example, the first change cows may make is to spend less time resting during a heat stress event. Normally, when a cow lies down, its internal temperature will increase, so instead, the cow will spend more time standing in order to thermoregulate. Dairy cows need 12 hours of rest per day to recover from metabolic stress and achieve their target milk production.
Under heat stress conditions, blood flow is also diverted away from the gastrointestinal tract to the skin to help dissipate heat. This can weaken the tight junctions that hold the enterocytes together, leading to leaky gut and inflammation.
All of these factors will have immediate consequences for dairy cows, such as reduced feed intake, an increased inflammatory state demanding extra energy expenditure, and a subsequent reduction in milk production. And over time, these changes can ultimately lead to dairy cow lameness in the fall, even after cooler temperatures have arrived.
There are three main reasons that heat stress in the summer can eventually lead to lameness in the fall:
The first step to preventing fall lameness caused by heat stress is to properly control heat stress during the summer with nutrition and heat abatement systems.
Nutrition and Performance Trace Minerals
There are very few ways that we can actually increase a cow’s energy intake by increasing the density of the ration because that could create some additional digestive and metabolic problems. So, the main thing that dairy producers need to do is preserve the highest-quality, most digestible forages for cows that are at a higher risk of becoming lame as a result of heat stress, namely transition and high-producing cows. Another important thing is to provide the cows with plenty of drinking water.
Additionally, dairy producers should add performance trace minerals to the ration. Zinc, manganese and copper are a critical part of maintaining the immune system in dairy cows and are basic components in the creation of quality hoof keratin, epithelium maintenance, ligaments and tendons.
Feeding more readily available forms of trace minerals, such as Zinpro Performance Minerals®, will help dairy cows absorb more nutrients and modulate the inflammatory response caused by heat stress while continuing to produce good quality hoof keratin and improve overall hoof integrity to prevent lameness.
Heat Abatement Strategies
When the temperature rises above 23 degrees Celsius (74 degree Fahrenheit) and an average humidity of 50%, dairy producers will need to implement ventilation systems to improve air movement. These systems should be installed in the milking parlor, the closeup pen and the main barn, ventilating at a rate of 10 kilometers per hour (~500 feet per minute) and providing a volume of 1.6 cubic meters of air per hour (~1000 cubic feet per minute). Under the same humidity, when the temperature rises above 28 degrees Celsius (82 degrees Fahrenheit) dairy producers will also need to implement heat abatement with water sprinklers to cool the cows in cycles.
Heat stress is one of the biggest factors contributing to dairy cow lameness. While heat stress can hinder milk production in the summer, the subsequent lameness could cause those negative consequences to continue in the fall. Investing in strategies to control heat stress – such as ventilation and sprinklers, as well as performance trace mineral nutrition – will always have a positive ROI.
The best managers are able to implement day-to-day strategies while keeping an eye toward the future. By implementing heat abatement strategies and including Zinpro Performance Minerals in the ration, you can control the negative impacts of heat stress during the summer while also working to prevent dairy cow lameness from popping up in the fall.
To learn more about heat abatement strategies or including performance trace minerals in your dairy cow nutrition program, contact your Zinpro representative today.