Five Nutritional Strategies to Minimize the Effect of Summer Heat Stress on Lactating Cows

Posted by Charles Soderholm, DVM, PhD Dairy Science on Jul 2, 2019 2:11:05 PM

Summer heat stress affects cows throughout the U.S., resulting in reduced feed intake, lower milk production, poor reproductive performance and excessive weight loss.  The reduction in milk yield associated with heat stress occurs primarily because of declining feed intake. The metabolic effects of heat stress can be minimized with practical knowledge, supplemental fats and other nutritional strategies.  

Here are five ways producers can maximize their cows’ health and production while minimizing lost profitability as the temperatures increase and heat stress becomes prevalent.

1. Keep cows hydrated with cool, clean water

First and foremost, never ever limit water and keep the supply abundant. Water is an important nutrient, and milk contains about 87% water.  Cows sweat and pant to combat heat stress, depending mainly on respiration to cool themselves in the hot summer months. 

Water intake is highly correlated with milk yield and DMI. Generally, cows consume 2 to 4 pounds of water for each pound of DMI and rations high in salt or protein increase water intake (Harris and Beede, 1993). By keeping clean water available at all times, cows can consume extra water to cool themselves internally, replace water lost through sweat and respiration and lessen the impact of lost milk yield.

2. Be proactive on your feed and bunk management

  • Push up feed more often. If the animal has any desire to eat, you want the feed to be available.
  • Mix and deliver fresh feed more often to minimize secondary spoilage, which will discourage the cow from eating.
  • Add a TMR preservative to improve bunk-life of mixed feeds.
  • Ensure a weekly cleaning of your bunks.  Summer heat and moisture cause spoilage, increasing the importance of cleaning feeding surfaces.

3. Increase potassium carbonate

Potassium (K) is involved in many biological processes in the body.  It is one the major minerals secreted into milk, is lost through sweating and is a key electrolyte in rumen fluid. Adding potassium carbonate to the ration can provide needed potassium to the body and can improve DCAD balance in the rumen, help buffer rumen pH, and help to prevent or alleviate milk fat depression

Increasing K levels to 01.4-1.6% of the ration dry matter with DCAD level of 25-50 have been successful in improving both milk fat yield and milk fat percentage. 

4. Increase nutrient density of the ration

Be sure to adjust diets to match with actual dry matter intakes, they will be reduced. 

Utilize higher quality forages to help increase the energy density of the diet. Keep in mind the heat increment of digestion is higher when consuming feeds high in fiber.  Feeding higher quality forages can reduce this extra feed source of heat. 

A recommended solution is to bump protein levels, as the extra protein in the diet not only can help reduce muscle tissue depletion, but also helps promote water intake which will keep cows producing milk and milk fat. At least half of the extra protein fed should be from a good rumen bypass protein source.

5. Feed a “cool fat” to a hot cow

Cows need more energy-dense diets during heat stress due to decreased DM intake and increased maintenance requirements.  

Although cows may not show signs of reduced heat stress in response to added dietary fat, cows will benefit from greater energy density during periods of depressed intake. Practical applications are to add fat, not exceeding 5 to 7% total fat in the diet. 

Utilizing dietary fat supplements high in Saturated free fatty acids (SFFA) improve milk and milk fat production during heat stress.  In an independent study, cows fed Energy Booster 100® did not experience increases in body temperature during the hottest time of the day and improved milk and milk fat production during heat stress.


While we can’t control Mother Nature, we can take steps to ensure that our Dairy cows are safe, healthy and achieving optimal milk production. Learn more about how to minimize the effects of heat stress through nutrition, or contact us to see how Energy Booster® can help maximize your profitability during hot weather.