Episode 356 - Heat Stress and Water Intake in Dairy Cows - UMN Extension's The Moos Room

This episode examines how heat stress affects water intake in dairy cows—and why farms must prepare their watering systems for increasingly hot weather.A review of studies from 1985–2024 found that Holstein cows producing roughly 65–70 pounds of milk averaged about 24 gallons of water per day under thermoneutral conditions. During heat stress, intake increased by approximately 10 liters, or 2–3 gallons, per cow per day. Each one-unit increase in the temperature-humidity index was associated with another 1.5 liters of water intake. Although heat-stressed cows produce less milk, they drink more because the additional water supports evaporative cooling and body-temperature regulation.Data from the University of Minnesota’s dairy herd revealed a more complicated picture. smaXtec sensors showed that cows averaged around 23 gallons per day, but estimated intake declined during summer. Possible reasons include warmer drinking water, pasture water access, competition at waterers, and changes in drinking behavior. Cows generally drank only four or five times per day, consuming roughly 14–20 liters at each visit. Peak drinking also shifted from midafternoon in winter to around 7 p.m. in summer, often after milking.These patterns highlight the importance of examining when cows drink—not just daily totals. Farms should ensure adequate water flow, tank capacity, access, and cool water during peak-use periods. Sensor readings are most valuable when compared with each cow’s normal behavior and interpreted alongside weather, milk production, rumination, health events, and management changes.The central message is that water intake can be a useful indicator of heat stress, but unexpected changes should prompt investigation rather than an automatic conclusion. As extreme heat becomes more common, dairy water systems must be designed for peak demand rather than historical averages.Questions, comments, scathing rebuttals? -> [email protected] or call 612-624-3610 and leave us a message!Linkedin -> The Moos RoomTwitter -> @UMNmoosroom and @UMNFarmSafetyFacebook -> @UMNDairyYouTube -> UMN Beef and Dairy and UMN Farm Safety and HealthInstagram -> @UMNWCROCDairyExtension WebsiteAgriAmerica Podcast Directory