I made a pledge this winter that I would not complain when temperatures approached triple digits this summer. Unfortunately, I broke that pledge. I lived for a while in the south and quickly decided that the heat was not for me. We all may be a little spoiled from the moderate temperatures the spring and early summer have brought. However, these higher temperatures have been expected and now we will deal with them like we always do. While most of us can escape the heat with our home air conditioners, our livestock do not have the same luxury. We need our animals to thrive in all conditions, but conditions can get extreme to the point that we need to help out where we can.
Our ruminant livestock are built for cooler weather as they are blessed to have a furnace in their bellies that will generate a lot of heat to keep them warm. As long as they are well fed, we don’t have a lot to worry about. This becomes an issue as temperatures moderate and humidity climbs. The Thermal Heat Index (THI) was originally developed by E.C. Thom in 1959. The index is a scaled system that factors ambient temperature and relative humidity to identify combinations where heat stress behaviors can be observed. The initial threshold is triggered at 70 degrees and 70 percent humidity. Mild heat stress can be reached at 75 degrees and 70 percent humidity.
The temperatures and humidity levels we reached last week would put us in the “extreme” category and our animals were feeling the effects. Heat stress produces visible behaviors. You have probably seen: Increase breathing rates, panting and open-mouthed breathing, drooling, restlessness, decreased feed consumption, and refusing to lie down. The animals can actually make it worse on themselves as when they are stressed their instinct is to huddle up, which may increase their heat load.
We need to do what we can to help them mitigate the stress they are experiencing. It begins with providing ample water. Most livestock drink a gallon of water for every 100 pounds of weight. During high temperatures, that can double to 2 gallons per 100 pounds. Besides just making water available, you want to keep your waterers clean and do what you can to keep it from building too much heat. If you are using large stock tanks, fill them a couple times per day. You should target early morning and later in the evening. Most animals drink right before they eat. If you have water lines running out into your pasture, they should be buried or covered in some fashion to keep the water in them from getting too hot by the time it reaches the animals.
Other recommendations:
- Provide sufficient shade for the herd
- Consider deploying a sprinkler system to wet the animals periodically
- Avoid working animals until the heat becomes more manageable
- Reduce grain supplementation
If you subscribe to our quarterly newsletter, it should have arrived in your email inbox last week. Those of you that receive it through the postal service, should see it soon. This edition provided a few flyers for upcoming programs that may be of interest. On July 22, the 2026 Manure Science Review will be held at Homan Inc., in Maria Stein, OH. For a description of this year’s program, or to register, you can go to go.osu.edu/msr2026. For those of you in Wayne County, we will be hosting a Manure Safety and Precision Application Field Day on August 4th at the Sterling Heights Dairy shop. The program will run from 10:00 AM to 2:00 PM. Lunch will be provided and the event is sponsored by OSU Extension, The Wayne Soil and Water Conservation District, and the Wayne-Ashland Dairy Services Unit. The program flyer can be found on our website’s events page at wayne.osu.edu. If you have not been getting email notices from me, or would like to receive a paper copy, contact the OSU Extension office at 330-264-8722.
This article was previously published in The Daily Record.