Do changes in feed intake or ambient temperature cause changes in cattle rumen temperature relative to core temperature?

A technique was developed to monitor and describe the relationship between core body temperature (Tc) and rumen temperature (Trum) in cattle. This relationship was assessed in cattle subjected to varying environmental temperatures and subsequent variations in dry matter and water intake. Increasing the environmental wet bulb temperature (WBT) from ambient conditions (approximately 15 °C WBT) to mild heat stress conditions (25 °C WBT) caused an increase in both Tc and Trum with significant decreases in feed intake and increases in water consumption. Despite increases in both Tc and Trum, reductions in dry matter intake, and an increase in water consumption, the relationship between Tc and Trum did not change.