Metabolic and Environmental Heat

Cows generate heat internally (metabolic heat) as a result of eating and digesting feed. Like most mammals, the dairy cow needs to maintain its core body temperature within a narrow range around 39oC – between 38.6oC and 39.3oC to be precise! The core temperature fluctuate slightly throughout the day, reaching a peak in the early evening and a low early morning. Cows also take on heat from the environment around them. The cycle of gaining and losing heat absorbed from the environment is on-going and always operates in the context of the metabolic heat a cow is carrying at any given time. Factors that determine the level of environmental heat a cow fains or loses over time are: