Influence of thermal conditions on use of a free-access cooled area by pregnant sows in collective pen

In our previous studies various cooling systems were tested to define the satisfaction of the sows and the results were based mainly on behavioural parameters. The behaviour of the sows really changes in relation to air temperature. A recent study has remarked the presence of threshold temperatures driving sows to move to comfortable areas during the day. In summer 2008 a new experimental trial was arranged in order to confirm some results of previous studies. In a collective pen for pregnant sows a cooled area was provided using two combined systems: - stream of air at high velocity, made of two pipes with exit diameter of 0.08 m and blowing air at high velocity towards the floor (12.5 m/s); - supply of water on the floor by a drip cooling system, using 25 drip nozzles, able to supply 3.5 l/h each, working 4 times a day for 3 minutes. The total amount of water was 36 l/day. The main aim of this paper was to verify the use of the cooled area by the sows in relation to the inside air temperature and the Temperature-Humidity Index. The use of the cooled area was checked using a close-circuit television system with infrared cameras. Furthermore RFID active tags were applied to the sows in a collar in the neck to collect information on times of permanence in the cooled area by each head. The time spent by the sows in the cooled area was related to the inside air temperature. The study has confirmed that sows use the comfortable cooled area during the day in relation to the temperature and to the Temperature-Humidity Index. The resting of the sows in cooled area rises proportionately to the increase of temperature and THI values.