Lyndsay Ritzler, MS Student and Dr. Grazyne Tresoldi, Assistant Professor, Department of Animal Sciences, The Ohio State University
Heat stress is a challenge that affects dairy cow welfare and production across the United States. With global temperatures on the rise and cows bred for higher milk yields, preventing and managing heat stress is more critical than ever. Fortunately, new tools are emerging to help producers monitor their animals and act early —part of a growing field known as precision livestock farming (PLF), which uses automated technologies in animal agriculture. These tools have become increasingly popular in recent years, thanks to advances in artificial intelligence and machine learning, making it easier to analyze large volumes of data. As a result, more companies are offering affordable, farm-ready technology to monitor cow health, production, reproduction, behavior, and the environment.
A wide range of precision tools is now available in dairy production, including collars, rumen boluses, pedometers, ear tags, and automated feeding systems. Brands like AfiMilk, MooMonitor+, CowMed, AllFlex/SCR, Lely, CowScout, Farmfit, CowManager, Grow Safe, RumiWatch, SmaXtec, and Nedap offer systems that track activity, feeding behavior, and body temperature—three key areas for early detection of heat stress. While many of these products are marketed for profitability, producers should carefully consider how accurate the data are, whether it applies to their specific herd, and most importantly, whether they can use the information to guide day-to-day decisions.
Activity Tracking
Changes in cow behavior are often early signs of heat stress. For example, cows tend to lie down and move less, often spending more time standing idle as they try to cope with the heat. Activity is typically tracked by using pedometers on the leg or sensors built into collars and ear tags. The AfiAct II (Figure 1), for instance, is a popular pedometer validated by multiple studies, though some studies report it may overestimate step counts (Borchers et al., 2016; Marques et al., 2024). Rumination collars track a range of measures, including rumination and lying time. A noticeable drop in lying behavior or rumination could signal early signs of heat stress and warrant closer attention.
Feed Intake and Behavior
Another key indicator of heat stress is a drop in feed intake or eating time. Systems like Grow Safe and Lely can track individual feed and water intake in real time, but their use on farms is still limited. More accessible tools include collars (Leso et al., 2021; Figure 2) that monitor rumination, since less chewing can signal lower intake—though rumination isn’t a perfect stand-in for consumption. Some ear tags, like CowManager (Figure 3), estimate eating time, but results vary. Collars also track feeding behavior, and while exact timing may be off, trends in eating time generally reflect changes in intake. RumiWatch noseband sensors aim to measure intake directly, though they’re more accurate for tracking rumination than actual feeding (Ruuska et al., 2016). While cows may eat less during the hottest hours, consistent intake over 24 hours is key. Tracking feeding patterns can help catch problems early.
Body Temperature Monitoring
One of the clearest signs of heat stress is a rise in core body temperature. Several rumen boluses on the market (e.g., SmaXtec) track internal temperature and have been validated in independent studies. However, because rumen readings can be influenced by feed and water intake—especially cold drinking water—producers should interpret them with caution. Some ear tags now include temperature sensors and offer additional insight, though they may still fall short of capturing true core temperature. Vaginal temperature remains the gold standard, but no commercial system currently provides continuous real-time data. Ideally, cows should maintain a body temperature at or below 102°F to avoid the negative effects of heat stress.
Balancing Costs and Practical Use
While the benefits of precision technologies are promising, adoption still depends on cost, ease of use, and how well the tools fit your farm’s needs. In regions like the Midwest, heat stress can cost producers up to $99/cow/year – losses that add up quickly in even mid-sized herds.
When considering a new system, ask yourself whether the data are accurate, whether it benefits your specific herd, and most importantly, whether it can support daily decision-making. In many cases, producers may already be using tools, like collars for reproduction or health monitoring, that can also help flag early signs of heat stress. Making full use of these existing systems can be a cost-effective first step. The right tool is the one that provides clear, useful insights for your cows and your conditions, helping you protect both welfare and production when the heat is on.
Why it Matters
Heat stress affects more than just milk yield – it compromises cow comfort, health, and overall well-being. PLF tools give producers a way to monitor behavior, feeding, and body temperature in real time, making it easier to respond early and prevent bigger losses. This not only supports production goals but also helps improve the overall quality of life for cows, strengthening both the economic and ethical foundation of dairy farming.
References:
Borchers, M. R., Chang, Y. M., Tsai, I. C., Wadsworth, B. A., and Bewley, J. M. 2016. A validation of technologies monitoring dairy cow feeding, ruminating, and lying behaviors. Journal of Dairy Science, 99(9), 7458–7466. https://doi.org/10.3168/jds.2015-10843
Leso, L., Becciolini, V., Rossi, G., Camiciottoli, S., and Barbari, M. 2021. Validation of a commercial collar-based sensor for monitoring eating and ruminating behaviour of dairy cows. Animals, 11(10), 2852. https://doi.org/10.3390/ani11102852
Marques, J. C. S., Burnett, T. A., Denis-Robichaud, J., Madureira, A. M. L., and Cerri, R. L. A. 2024. Validation of a leg-mounted pedometer for the measurement of steps in lactating Holstein cows. JDS Communications, 5(1), 67–71. https://doi.org/10.3168/jdsc.2023-0403
Ruuska, S., Kajava, S., Mughal, M., Zehner, N., and Mononen, J. 2016. Validation of a pressure sensor-based system for measuring eating, rumination and drinking behaviour of dairy cattle. Applied Animal Behaviour Science, 174, 19–23. https://doi.org/10.1016/j.applanim.2015.11.005
Figure 1. AfiMilk brand pedometer (AfiAct II) mounted on a cow’s
leg to monitor activity levels (Source: afimilk.com)
Figure 2. Allflex Heatime HR collar being used on a free stall dairy farm
(Source: G. Tresoldi).
Figure 3. CowManager ear sensor attached to the ear of an animal
(Source: cowmanager.com)