An Active Drying Sensor to Drive Dairy Cow Sprinkling Cooling Systems

The use of sprinkling with ventilation to cool dairy cows is considered an appropriate practice to reduce the negative effects of heat stress. However, due to climate change, water will increasingly become a limited resource, so we need to make water use more and more efficient. For this purpose, an active drying sensor has been developed in order to time the sprinkling cooling system. The sensor reproduces the thermal response of a cow, considering both sensible and latent heat exchange, and is located in the feeding alley, about two meters above the floor. This allows the fabric of the sensor (simulating the fur) to be wetted by the sprinkler, and blown by the fan. The water content of the sensor fabric during the drying time is monitored by measuring its electrical conductivity, allowing the estimation of the time the fur becomes dry. Another two specifically designed instruments are presented, the first to estimate the fur's water content after spraying, and the second to detect the time the fur became dry. Sensor output, interpreted through a simplified model, gave a predicted drying time with an error ranging between -11.4% and +14.8% (R-2 = 0.789). In the commercial barn where the experiments were conducted, the use of the sensor allowed an estimated reduction in water consumption of about 57%, with respect to the fixed timing normally used. As a perspective, the sensor could be used to assess cows' heat stress level.