ISSUE FOCUS 30 FEED & ADDITIVE MAGAZINE June 2024 Dairy farmers know the importance of keeping their cows cool and comfortable. Unfortunately heat stress isn't just a threat in scorching deserts – even moderate climates can bring periods of discomfort for a herd. Heat stress in dairy cows is a significant issue that affects their productivity and overall health. It is essential for dairy farmers to manage heat stress effectively to ensure optimal milk production and longevity of their herds. Here is what you need to know to keep cows cool and productive during warm seasons. People might think heat stress is only a concern in hot, dry areas. However, dairy cows in moderate climates like Europe and coastal areas of Latin America and North America can also suffer from heat stress during warm and humid periods. While cows can develop some tolerance to heat stress with regular exposure, those in moderate climates may struggle to adapt quickly to sudden spikes in temperature. Climate change has made heat stress a more frequent issue globally. The key to preventing heat stress lies in understanding how cows regulate their body temperature. Unlike humans who can sweat freely, cows rely on panting and increased respiration to cool down. This process comes at a cost – reduced feed intake, digestive issues, and ultimately, a drop in milk production. RECOGNIZING THE SIGNS EARLY Dairy cows strive to keep their body temperature between 38-39ºC (100-102ºF). Unlike other species, they produce a significant amount of heat through metabolic processes, especially during the microbial fermentation of feed in the rumen. A highly productive dairy cow generates even more metabolic heat, making them more susceptible to heat stress. Rising global temperatures and increased milk production have led to longer periods where cows exceed their heat load capacity, resulting in heat stress. Look for these clinical signs of heat stress in your cows: • Panting • Drooling • Milk leakage • Reduced milk production • Prolonged standing The Temperature Humidity Index (THI) is a common method for quantifying the risk of heat stress by combining environmental temperature and humidity (Figure 1). While threshold values often reference cows acclimatized to high temperatures, in temperate regions, cows can show signs of heat MANAGING HEAT STRESS IN DAIRY COWS TO MAINTAIN PRODUCTION Lonneke Jansen Technical Commercial Manager Selko Feed Additives
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