In moderate climates, heat stress can already occur at 20°C
Heat stress in dairy cows is a common problem, even in moderate climates. Due to global warming, it is a growing problem. Milk production, and fertility[67,68] in dairy cattle will be negatively affected by heat stress and the incidence of lameness and mastitis will increase[75,80]. Heat stress can be an important potential cause of systemic immune activation, which in term can result in involuntary culling of dairy cows.