From the Dairy Cattle Reproduction Council edited by George Heersche, Jr.

Options to Help Deal with Heat Stress

While it’s not possible to completely overcome the effects of heat stress, there are a number of options to help deal with heat stress and mitigate its effects on your herd.

  • Use technology to keep cows cool. Provide them with access to shade, forced air ventilation and some form of evaporative cooling, such as sprinklers.
  • Implement and maintain cooling. Make sure current cooling systems are ready for summer and determine whether upgrades are needed.
  • Always have water available. Ensure cows have access to plenty of fresh, clean water—and set up a schedule of waterer maintenance throughout the summer. Consider adding waterers to exit lanes if you have not already done so.
  • Assess reproductive programs. Add estrous detection aids if your program depends on estrous detection for success. And consider incorporating artificial insemination (A.I.) protocols that remove estrous detection from the equation if your dairy struggles with accurate heat detection during the summer months.
  • Remember the bulls. Bulls are impacted by heat stress too, so consider using A.I. for more breedings before sending repeat breeders to a bull pen.


Cool Cows Sooner Rather than Later

It’s easy to see the effects of heat stress on a warm summer day, but heat stress is a function of temperature and humidity and shows up long before the mercury in the thermometer rises.

Today’s high-producing dairy cows begin to feel the effects of these parameters more quickly than previously thought. In fact, milk yield losses become significant when the minimum temperature-humidity index (THI) on any given day reaches 65 or higher. Therefore, rather than set cooling to begin when the temperature reaches 72 degrees F, ratchet that threshold down to help cows more effectively deal with heat stress.