Dairy farmers throughout the west are expected to combat their first high-heat week of 2020. The rest of the country is expected to experience these same increased temperatures over the next 10 days. According to Dan McFarland of Penn State Extension, productive dairy cows may experience heat stress when the Temperature Humidity Index (THI) is 68 or greater.
“In ‘more humid’ climates this can occur at temperatures as low as 72oF,” he says. “Heat stress can be reduced by slowing heat gain to the cow and improving heat transfer rate from the cow.”
Tracey Erickson of South Dakota State University Extension, there are five simple ways to improve heat tolerance of lactating dairy cows.
1. Increase access to clean, fresh drinking water. Increased respiration and urination during hot weather may increase drinking water intake by 20% or more, McFarland says. Farmers should consider adding extra tanks of water and checking for appropriate flow of water in drinking fountains, according to Erickson. “Consider adding temporary water access such as a split PVC pipe with flowing water or portable tank to cows as they leave the parlor,” she says.
2. Provide cow cooling in parlor holding pens. Cattle that are being exposed to a holding pen in a parlor should be cooled by a combination of air movement, water sprinkling systems and shade, Erickson says.
3. Maximize air flow. Make sure all fans are working while providing the proper maintenance and cleaning, she warns.
4. Adjust diets. Cows eat less when they are hot. As dry matter intake decreases, consider utilizing higher quality forages and increasing the energy density of the diet, Erickson says. “As diet adjustments are made, care should be taken to make sure that there is enough effective fiber to maximize rumination and keep acidosis and displaced abomasums to a minimum,” she says.
5. Feed when it’s cool. An easy way to encourage cows to eat more is to adjust feeding delivery to the cooler times of the day, Erickson says. Additionally, it’s wise to increase the number of times feed is pushed up to minimize sorting.
Don’t forget calves are impacted by heat stress too. Check out these resources for tips to help calves deal with hot temperatures.