Characterisation of an experimental water-cooled cover for sows

Abstract

Heat stress relief for sows in hot and humid climates remains a challenge. This study investigates a cooling method that is intended to enhance heat dissipation from sows. The experimental device was an aluminium cover (1.5 m long by 0.65 m wide and either 0.8 m or 0.95 m high) fitted with water-cooled pipes (25 mm diameter, spaced at 100 mm, 150 mm or 200 mm) and attached to the frame of the gestation sow crate. Performance was evaluated for cooling water temperatures of 15 or 20 °C under ambient summer conditions. Results showed the black-globe temperature (BGT) in the simulated sow-occupied zone (SOZ) was reduced by the addition of the aluminium canopy by 3 °C at 200 mm tube spacing and 37 °C ambient temperatures. The narrower the tube spacing the greater the cooling potential, with the 100 mm tube spacing yielding a SOZ BGT reduction of 6.1 °C at 39 °C ambient temperatures. The results demonstrated that the larger temperature difference between ambient air and inlet water the greater the effect of the heat exchange, and that water of 20 °C or cooler could be used as the cooling water supply. The cooling potential with a 0.8 m high canopy was greater than that at 0.95 m. It was concluded that the cooling efficiency of the water-cooled cover was affected by the inlet water, the surrounding environment, and the structure and size of the canopy.