Heat Stress in Livestock: Understanding the Impact and Management

(Updated: July 16, 2024, 12:03 p.m.)

With the hot and dry weather not slowing down, I’m sure we are all feeling bouts of “heat stress” but what does that really mean for our livestock? “Heat stress” is physiological stress because of high environmental temperatures and humidity. It is a major threat to production as it alters the animal's physiological response, negatively affecting daily gain, milk production, and reproductive performance. Understanding its effects and implementing effective management strategies are crucial for maintaining animal health and agricultural productivity.

In both cattle and small ruminants, signs of heat stress are labored or open-mouth breathing, head hanging low, and drooling or foaming at the mouth. They rely on heavy breathing or panting to cool themselves down. Cattle and small ruminants both sweat but not effectively enough to cool themselves down. On the other hand, horses have many sweat glands that offer an efficient cooling mechanism. In poultry heat stress is harder to detect, however if you can observe them panting, acting lethargic, or keeping their wings spread these are signs your flock is experiencing heat stress. Heat stress can be fatal, it is not something to take lightly!

During times of high heat livestock animals will have a decreased feed intake and become dehydrated much more easily, neither of which are good for production. In turn, this leads to poorer weight gain, reduced reproduction rates, and decreased milk production in our cattle, sheep, and goats. In poultry however, this can lead to reduced egg production.

With this in mind, what are some management strategies that can help reduce the effects of heat stress?
  • Ensure all animals have access to adequate shade to reduce direct exposure to sunlight.
  • Provide clean, fresh, cool water at all times to prevent dehydration. Consider adding electrolytes to promote water intake.
  • Establish good ventilation in barns, and if at all possible add fans or sprinklers.
  • Do not work your animals in the heat of the day! Schedule activities such as feeding and handling during cooler parts of the day.
  • Control flies as much as possible, this is just another stressor.
  • Check animals regularly for signs of heat stress. Heat strokes can turn fatal quickly so have a plan ready.
Below is a chart highlighting both temperatures and humidities resulting in heat stress. Heat stress can start at temperatures as low as 70° F, so be mindful in your management strategies.
Temperature vs Relative humidity, showing higher humidity and temperature leads to greater stress.

Heat stress in livestock is a dynamic challenge that requires proactive management to minimize its impact on animal welfare and agricultural productivity. By understanding the physiological effects, implementing appropriate strategies, and continuously monitoring conditions, we can effectively mitigate the risks associated with heat stress and ensure the well-being of their livestock.