Managing Heat Stress For Cattle

Published on Thu, 05/17/2018 - 12:30pm

Managing Heat Stress For Cattle

With proper environment management, heat stress can be handled effectively, keeping your herd comfortable, happy, and producing quality milk.

By Aly McClure for American Dairymen

With summer knocking on the door it’s important to remember it’s not “if,” but “when” will we have a prolonged period of heat and humidity. That is the nature of the season and dealing with the potential of heat stress in dairy cattle is more or less a management issue than anything else. Every area of the country deals battles short-term weather conditions – it’s how you handle those conditions that matter.

A lot of people use the terms climate and weather interchangeably, this, however, is incorrect. Each of our communities and farms is affected by short-term weather events. Their long-term sustainability is affected by climate and climate variability caused by natural positioning and earth rotation. For example, dessert is a climate, windy with a high of 95 is the current weather. Your weather is also indicative of your local climate.
Cattle born and raised in certain climates become resilient to the local weather patterns, but during the extreme weather seasons, specifically January-February, and July-August, it is essential to evaluate potential stress situations daily. You can do this during the summer by paying attention to the heat index. Remember, though, that dark-hided and finished cattle are more susceptible to heat stress than lighter colored and weighted cattle.
The Cattle Comfort Advisor is a heat index that evaluates the weather conditions across the country and determines the potential for heat stress. The values do not represent exact temperature; they are a way to measure the heat and cold levels an animal is being exposed to ranging -20 (cold Danger) to +120 (Heat Danger.) Cattle are the most comfortable when the index range falls between 15 and 85. When the scale begins to creep over the 85 mark that means it is time to start preparing and watching for heat stress, even changing your schedule to work animals during the coolest parts of the day. You can find an active map that is updated with the current index hourly at,
Cattle are the most comfortable when the outdoor temperatures hang around 35-75 degrees Fahrenheit. Depending on body condition, hide color, and hair length they do very well in this ideal temperature range. As the temperature begins to rise, they become increasingly uncomfortable. Cattle do not handle heat as well as humans do, they primarily have trouble when temperatures reach 90 and above. High heat conditions cause milk production to drop by a gallon or more per cow it will also decrease their fertility and pregnancy rates.
Reduced feed intake during periods of high heat stress is critical to monitor with lactating and pregnant cattle. Whenever feed intake has diminished the nutrient concentration should increase to accommodate health and production. The best feed you can offer during these periods is a high-quality ruffage that will process quickly resulting in less internal heat needed to digest the feed. Care should be taken when rearranging rations, especially when reducing quality but increasing nutrients to avoid digestive problems such as rumen acidosis.
The best ways to help your cattle through this time while reducing the opportunities for heat stress are as follows:
• Access to fresh, cool, and clean water. A cows intake increases to between 25-50 gallons of water a day during high heat. A dehydrated cow results in reduced milk production and in more extreme cases leads to a dry cow. So keeping plenty of fresh water in front of her is a necessity.
• A shady area to relax. Give her a break with the ability to cool down. Her body is working hard to continue to produce milk and grow calves. With access to a shady place to rest you will give her the ability to calm down and reduce stress.
• Maximize the access to airflow for penned animals. With a minimum required air flow of 5-10 mph for optimum cooling, it is imperative to keep the cattle in an open and breezy facility.
• Pest control for flies and parasites helps prevent the animals from crowding together, creating even more heat, to protect themselves.
• Work during the early hours when it is still cool so that the animals can rest during the heat.
A lot of handling cattle heat stress is paying attention to the weather and providing adequate protection from the elements. Planned management and alternative cooling sources such as sprinklers are also a good consideration to have depending on your location and may make a significant difference in the comfort of your animals.
Just as significant as managing the heat stress of your cattle is the heat stress on yourself or your personnel. Altering work hours to those of cooler times will benefit humans and animals alike. Make sure your staff is taking adequate breaks during stretches of high heat and hydrating properly. It’s never a bad idea to keep a few bottles of Pedialyte on hand.
As we wander into the dog days of summer, keep an eye on the weather around you, making slight changes on a regular basis will keep you from having to attend to critical situations.