Source: Dairy Herd Management 

Heat stress poses significant risks to dairy cattle, including calves, affecting their health and performance. Dr. Jimena Laporta, an expert in lactation physiology at the University of Wisconsin, has studied heat stress extensively. Contrary to conventional wisdom, calves are not less affected by heat and humidity than adult cows. Calves have a thermoneutral zone of 50-72°F, and conditions outside this range force them to divert energy from growth and immune function to temperature regulation.

Laporta’s research found that calves in Florida experience heat stress at a Temperature-Humidity Index (THI) of 65, while in Wisconsin, the threshold is 69. Heat-stressed calves show reduced milk intake and growth, delayed conception, and lower first-lactation milk production. Laporta advocates for heat stress abatement measures, such as mechanically ventilated calf hutches powered by solar panels, emphasizing the long-term benefits of proper calf rearing. “We are investing in our calves for life,” she stated.

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