Cooling regime timing set by bolus sensor mitigated heat stress in dairy cows

This research paper addresses the hypothesis that heat stress can be mitigated better by tailoring the cooling management to the cow's feeling. In the summer, cooling systems help the high-yielding dairy cows to maintain body temperatures in intensive systems. Those cooling systems often function at a constant schedule, based on measurements of the environment and not of the animal itself. We propose a method utilising a dynamic cooling system, based on sensors that measure the cows' core temperatures. Thus, cooling can be activated when needed, and is most efficacious. A total of 30 lactating cows were randomly assigned to one of two groups which received two different evaporative cooling regimes: a control group, which received the common methods used in farms, time-based cooling; and an experimental group, which received the sensor-based cooling regime, that was changed every week (3 month in total) according to the cow's response to last week's change in terms of body temperature, as measured by reticulorumen boluses. The two groups of cows had similar milk yields (44.7 kg/d), but those in the experimental group had higher milk fat (3.65 vs 3.43%), higher milk protein (3.23 vs 3.13%), higher energy corrected milk (ECM, 42.84 vs 41.48 kg/d), higher fat corrected milk 4%; (FCM, 42.76 vs 41.34 kg/d) and shorter heat stress time (5.03 vs 9.46 hours/day) compared to the control. Dry matter intake was higher in the experimental group. Daily visits to the feed trough were less frequent, and with each visit lasting longer. The sensor-based cooling regime may be an effective tool to detect and ease heat stress in high-producing dairy cows under summer heat load in arid and semi-arid zones.