Heat Stress in Beef Cattle

What is heat stress?

Healthy cattle can handle some heat stress, but high temperatures — especially in combination with high humidity and limited air movement — can have potentially deadly consequences. Not surprisingly, dark-hided cattle are at an increased risk for succumbing to heat stress. Beyond mortality concerns, heat stress can also decrease feed consumption, lead to lower conception rates and impact immunity.

Signs of heat stress in beef cattle

• Increased respiration (open-mouthed panting)
• Decreased activity
• Bunching (typically in shade, if available)
• Agitation
• Excessive salivation
• Reduced feed intakes
• Increased water consumption
• Crowding at water tanks
• Less rumination
• Acidosis

Preventing heat stress in beef cattle

• Provide shade, if possible. Cattle experience lower respiration rates, decreased body temperatures and less aggression when provided with adequate shade.
• Clean water tanks regularly. Cattle can drink 20–30 gallons of water on a normal day, but they may drink as much as 50% more when the temperature and humidity indexes rise. Providing fresh, clean water will encourage cattle to drink more and stay hydrated.
• Feed during cooler hours. Cattle don’t like to consume hot feed, and feedlot rations are prone to heating when left out. By unloading, mixing and feeding in the morning, cattle can eat before the feed gets hot and ruminate during the warmer hours of the day.
• Watch for manure inconsistencies. Decreased rumen fermentation efficiency occurs when cattle are experiencing heat stress, leading to lost nutrient utilization. Reformulating the ration can help achieve optimal nutrition potential during periods of decreased dry matter intake.
• Keep an eye on stocking density. Confining cattle in close proximity can have a significant impact on their microclimate. Because of this, any measurement of ambient temperature and humidity that can assess the possibility of heat stress should be completed at cattle level within their confined space.
• Ensure access to feed. Depressed intake is commonly related to heat stress. By providing continuous access to feed, cattle will eat small amounts throughout the day, which will help to reduce the thermal heating that would otherwise be produced during the consumption of large meals.
• Feed more digestible, high-quality forages. Since cattle are prone to eating less when hot, providing efficient access to nutrients is essential to health and production. First-cutting or fermented forages provide energy without requiring as much rumination as more fibrous feeds, thereby reducing provisional heating.
• Utilize a yeast culture additive. Yeast cultures have been found to stimulate the bacteria in the rumen responsible for both fiber digestion and acid removal. This will aid in improved fermentation efficiency and prevent acidosis, which can decrease body temperature.