09/06/2026
As the fall run approaches and producers prepare to wean or purchase stockers this is certainly something to keep in mind. It has been 100° or more for weeks on end here and it doesn't look like it will be letting up anytime soon so heat stress is imminent.
Heat stress in cattle can trigger conditions like rumen acidosis due to a disruption in feed consumption, reduced saliva buffers, and altered acid-base balance in the body.
Cattle will increase their respiratory rate and pant during heat stress. This rapid breathing affects carbon dioxide levels in the blood resulting in respiratory alkalosis. The body compensates by excreting bicarbonate in urine, which indirectly depletes the body’s ability to buffer rumen pH thus increasing the risk of rumen acidosis.
Cattle change their eating patterns during heat stress. They eat less during the day when it’s hot, and they tend to eat more at night when it cools down. However this type of binge eating can also overwhelm their rumen, further increasing the risk of rumen acidosis. Heat-stressed cattle often consume less forage, leading to a higher concentrate-to-forage ratio in the diet creating an environment favorable for rumen acidosis. Additionally, excessive drooling during heat stress decreases natural buffers needed to neutralize rumen pH.
Cattle that are drooling and sweating excessively during heat stress, often lose important minerals like potassium and sodium. This can further disrupt their body and lead to electrolyte imbalances and metabolic disturbances.
A sudden drop in rumen pH below 5.0, generally will result in severe clinical signs with negative outcomes unless corrected. This acidity can decrease rumen motility, damage the rumen lining, and draw systemic water into the intestinal tract causing severe dehydration from diarrhea. A secondary bloat may also occur.
Ways to help combat these conditions include backing off highly fermentable feeds during excessive heat to prevent grain overload and increasing the availability of a high quality forage instead. The mastication of forage physically stimulates the salivary glands to produce more saliva, which protects the digestive tract by neutralizing rumen pH. Additionally, uilizing products that support rumen stabilization such as sodium bicarbonate (baking soda), ionophores, and probiotics in the ration can help prevent and manage rumen acidosis. Always offer clean and fresh water with added electrolytes during excessive heat to help prevent dehydration in recently received calves that are at risk for metabolic imbalances. Providing adequate shade with air circulation is also critical to keeping cattle cool and comfortable during excessive heat.
