Heat Abatement in Dairy Cattle

by Katie Swenson, West Salem Feed Nutritionist

Posted: 7/25/2022

Now that we’re in the hot months, paying attention to the temperature and humidity is very important when it comes to your animals. Heat stress can affect your cows in some very negative ways, including reduced milk production, reduced feed intake, rumen acidosis, and milk fat depression, among others.

The optimal temperature for dairy cattle is 40-60 degrees, and cows have shown symptoms of heat stress at temperatures as low as 65 degrees. Counting respirations is one way to spot heat stress. Normal respiration for cows is 40-45 per minute (normal body temperature of 101.5 degrees).

There are a few ways we can help keep our cows cool this summer including areas of shade, air movement and water. The most common way to cool is through shade. This can be from a barn roof, tree cover, shade cloth, etc. Often, we see an opportunity for shade improvement in free-stall barns. If cows are avoiding certain stalls in the morning or afternoon, watch the sun pattern. Cow comfort and stall utilization can be improved by installing shade cloth to block the sun from hitting the stalls. Air movement is also important to keep cows cool.

The velocity during periods of possible heat stress should be 4-6 mph, regardless of barn type. This can be achieved by placing fans over stalls and feed lanes, as well as in holding areas. For existing fans, cleaning the blades of debris in the spring before they get turned on will help keep the velocity up to what the fan is rated for. It can also help keep the electric bill lower, as clean blades take less power to turn than heavy, dirty blades.

Drinking water requirements increase with the ambient temperature. Make sure adequate water space is provided to all cattle. The most common recommendation for water space is four inches per cow, and at least two watering areas per group. A cow will drink up to 10 percent of her daily intake immediately after milking if water is available, so having water available along exit lanes of the parlor is significant.

The other facet of water, when it comes to heat stress, is evaporative cooling. A cow’s main sweat glands are around the nose and udder, so by applying water to the back of the cow and with air flow to help evaporation, we can cool the body temperature of the cow down significantly. Lactating cows are not the only group that needs cooling.

Cooling dry cows is also extremely important. Studies show cows cooled during the dry period will have a higher milk yield in the coming lactation, produce heavier calves, and have a higher dry matter intake at calving than cows not provided with cooling. If you have any questions on how to implement cooling systems at your farm, contact your Provision Partners feed representative!