Direct surface wetting sprinkler system to reduce the use of evaporative cooling-pads in meat chicken production: indoor thermal environment, water usage, litter moisture content, live market weights and mortalities

An overhead sprinkler system that directly applies water onto meat chickens in tunnel ventilated houses was evaluated and compared to a conventional evaporative cooling-pad system at two commercial farms in south-eastern Queensland, Australia. The sprinkler system was used to reduce the use of evaporative cooling-pads as the primary cooling system, but not replace evaporative cooling-pads altogether. The sprinkler system used low water pressure and was comprised of evenly spaced sprinklers and a programmable controller. Water was applied intermittently based on house temperature and a temperature program that was related to bird age. The study was conducted over six sequential grow-outs during a one year period. Air temperature, relative humidity, litter moisture content, cooling water usage, live market weight and mortality were assessed during the study. The effect of sprinklers on these measured parameters was complicated by interactions with farm, batch, bird-age and time-of-day. We found that, in general, houses with combined sprinkler and evaporative cooling-pad systems used less water, while having similar litter moisture content, live market weight and mortality compared with control houses that were fitted with conventional evaporative cooling-pads. When evaporative cooling was required, sprinkler houses had warmer air temperature but lower relative humidity than the control houses. Bird comfort due to the direct cooling effect of water evaporating off the birds was not directly assessed during this study, but was inferred from thermal camera images and from live weight and mortality data. This was the first study in Australia involving this sprinkler system, and we suggest that the sprinkler system design and operation may require some adaptation to better suit Australian poultry house design and climatic conditions, including the need for additional sprinklers to improve coverage, lower set-point temperatures, and altering sprinkler spacing to suit ceiling baffle curtains (if fitted).