Systemic inflammation as a result of heat stress reduces performance of dairy cows

Rising temperatures and more frequent heat waves in recent years have brought the issue of heat stress into sharp focus - not just for humans, but also for dairy and beef cattle. The impact on cows is significant and multifaceted. Heat stress not only reduces dry matter intake, but also contributes to leaky gut, oxidative stress, altered rumen function, and systemic inflammation. These effects compromise nutrient utilization, immune response, and overall animal performance.

Studies using pair-fed animals—where heat-stressed cows are compared to cows in cooler conditions but given the same reduced feed—have shown that only about 50% of the milk production loss is due to reduced feed intake. The other 50% is linked to the physiological stress response, including inflammation and metabolic changes, which directly affect productivity (see Figure 1).