ISSUE FOCUS 40 FEED & ADDITIVE MAGAZINE July 2025 Environmental temperatures have increased by 1.0 °C since the 1800s. They are expected to increase by another 1.5 °C between 2030 and 2052. As a consequence of global warming, an increase of the frequency of hot days and heat waves is observed, leading to a higher risk of heat stress for farm animals. Heat stress results from the animal’s inability to dissipate sufficient heat to maintain homeothermy and is defined as the sum of internal and external forces that act on an animal to cause an increase in body temperature and evoke a physiological response. Due to their high metabolic heat load, dairy cattle are very susceptible to heat stress. To alleviate the effects of heat stress, dairy cows automatically undergo a series of physiological responses in an attempt to maintain internal homeostasis. The stress response leads to elevated levels of cortisol in the blood as well as an inflammatory response which in turn can have a negative impact on gut integrity. Seeking shade, increased water intake, drooling, a higher respiration rate and body temperature are effects to be observed in heat stressed dairy cows. But also a reduced dry matter intake and a lower frequency of rumination is seen, leading to a lower ruminal pH, an altered rumen function, and an increased risk of acidosis. Reduced milk yield (and fat), lower pregnancy rates, more lameness and diseases are the consequence, leading Dairy cow health is increasingly threatened by rising temperatures, leading to physiological stress responses, reduced feed intake, and performance losses. A field study observed notable effects on milk yield, feed efficiency, and stress indicators under moderate heat conditions. While outcomes suggest promising nutritional strategies, especially under compounded stressors, further details and long-term implications are explored throughout the article. Dairy Cow Health Under Heat Stress: THE ROLE OF ISOQUINOLINE ALKALOIDS Lucas Queiroz Product Manager Sangrovit® Phytobiotics Futterzusatzstoffe Julia Schmitt Manager Competence and Science Phytobiotics Futterzusatzstoffe
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