Dealing with Heat Stress in Livestock

Written by Allison VanDerWal, Form-A-Feed Beef Nutrition Intern and Heidi Doering-Resch, M.S - Form-A-Feed Beef Technical Services

Summer is finally here and the warm weather is upon us. After a long cold winter everyone looks forward to a little warmth of summer. However, the summer heat, when excessive, can cause major problems in the feed yard with economic losses totaling in excess of $75 million due to production losses. Heat stress is a serious problem in to production agriculture and as producers we can never be too informed on how to protect our livestock.

How does heat stress affect my livestock?

In a heat stress event, cattle work to cool themselves which comes as an expense to performance. Cattle under heat stress typically decrease their dry matter intake (DMI).  As cattle eat, energy and heat are produced as feed is fermented which in turn increases the temperature of the animal. This decrease in DMI is a big problem to most producers. Not only does this decrease pounds of gain in feedlot cattle because cattle are only consuming enough energy or feed to maintain themselves, but in some cases, energy is released from the muscle to compensate for a decrease of energy and nutrients consumed in a ration. This can cause an increase in dark cutters if cattle are shipping during a heat event. It can also cause a reduction in quality grade.

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Heat stress also affects the health of the rumen. If a heat stress event occurs, rumen pH begins to fluctuate which can result in acidosis. This causes a breakdown in the villi in the rumen leading to a decrease in the absorption of essential nutrients. Heat stress is partially to blame for seeing more instances of metabolic acidosis during the summer months.

One misconception producers have is that cattle start losing performance once they see them panting or exhibiting signs of heat stress. Cattle actually start losing performance once the temperature humidity index (THI) registers at 68°.  Thus cattle can be hardly panting and they are already mobilizing energy towards cooling instead of digestion. Temperature humidity index takes into consideration the ambient temperature plus relative humidity.

What are some symptoms of heat stress?

  • Dry matter intakes decreases.
  • Cattle will tend to crowd around the water tanks, or in shaded areas of their pens.
  • Respiration rates increase. 
  • Cattle lower their heads and extend their necks.
  • In more severe cases, cattle will pant with their tongues out.
  • Death occurs once the animal loses its ability to cool itself.

How can we cope with a heat stress event?

Since we cannot change the weather, all we can do is prepare for a heat stress event and manage our cattle through it by adapting on-farm management practices and obtaining support from Form-A-Feed's heat stress consultants. One of the biggest things we can do as producers to survive these events is be aware of our management practices and make improvements where they are needed. Some things you can work on as a producer are: 

  • Check respiration rates of your animals in heat stress events. 
  • Keep track of dry matter intakes.
  • Make sure your water tanks have a 10 gal/minute flow rate and that you have at least a 0.5" inches/head of water space. Add more water space during severe events.
  • Make sure to clean water tanks at least once a week, and check them daily for fill or contamination.
  • Provide shade for your animals.
  • Keep pens clean and bedded and make sure you have the correct stocking density for your facility.
  • Install a fan and sprinkler system as a cool down system.
  • Adjust feeding strategies to feed at cooler times of the day and maintain ration condition.
  • Use Hydro-Lac®, in conjunction with the Hydro-Lac heat stress app, to support cattle metabolically.

As producers, heat stress is not something we should be afraid of but become aware of. Knowing the signs, how to prepare for, and what you can do to cope with heat stress simply leads to more pounds preserved and sold.Adding Hydro-Lac to your summer heat stress program and becoming aware of heat events with the new Hydro-Lac Heat Stress App are important tools most producers are using today. Instead of trying to cool the animal from the outside in, Hydro-Lac helps cool the animal from the inside out. By hydrating that animal prior to and during heat stress events, that animal is more likely to maintain production and rumen health since DMI is more stable and there is less stress on the rumen. This leads to higher quality carcasses, more pounds of product to sell, better animal welfare and higher returns on investment.