I recently had the opportunity to share my work with the Central Valley dairy community during the Managing Cow Comfort in Hot Weather seminar sponsored by U.C. Cooperative Extension in Tulare, CA.
Although my talk was titled “Soakers to cool cows: Can we reduce water use?“, I am not just interested in reducing water use. Rather, I’m interested in using it more judiciously and efficiently, which includes identifying when cows may need more spray cooling from soakers.
I talked about how when cows begin to accumulate excess body heat, they show physiological and behavioral responses to avoid gaining more heat, or to dissipate body heat.
This includes breathing faster to release heat through evaporation. Normal cattle respiration rate is around 40 breaths/min or less, whereas over 80 breaths/min is clearly elevated – a sign that body temperature may be rising above normal as well. It’s important to intervene by providing cooling when some cows start breathing rapidly, as this is a sign that the rest of the herd will soon follow.
Dr. Don Spier’s group at University of Missouri developed a great (and free!) smartphone app that can help record respiration rate – it’s called Thermal Aid, and NPR did a story about it a few summers ago. I demonstrated how to use the app for this purpose, using videos I took of cows breathing normally or rapidly.
Research has shown that soaking cows with water can help keep body temperature within the normal range. My own work has found that when we offer cows 24-hour access to soakers, they will start seeking out cooling in the morning, when the air temperature is only 73°F. By doing so, they keep their body temperature in the normal range for the rest of the day.
But how much water is needed to cool cows effectively? This has been a focus of my Ph.D. research. We have found that after a certain point, applying additional water gives diminishing returns for cooling cows. Across 2 studies, we showed that applying 1.3 L/min (0.35 gpm) in intermittent 3-min cycles is as effective as applying > 4.5 L/min (1.2 gpm) for the same amount of time. The next steps are to see how these results will hold up under large-scale commercial conditions, and to investigate other ways to reduce water use (such as changing the timing, and developing sensors to detect when cows are near the sprinklers).