Water vapour emission and nitrogen balance from a sawdust deep litter system for weaned pigs

Five batches of a total of 180 weaned pigs were reared successively in an experimental room on 30 cm deep litter without cleaning between the batches. The litter was a mixture of sawdust from coniferous and beech trees. Water was added to the Litter every 10 days to lower the dust concentration in the room. The total amounts of sawdust and water used were respectively 21.3 kg per pig and 10.21 per pig. The mean temperature of the litter at 20 cm depth recorded during each of the 5 periods varied from 32.5 degrees C to 41.8 degrees C. The average liveweight of the pigs at the beginning and at the end of the post-weaning period was respectively 7.9 +/- 1.2 kg and 24.5 +/- 4.2 kg. The average daily gain was 392 +/- 87 g. The temperature and the relative humidity of the air inside and outside the experimental room and the ventilation rate were continuously recorded in order to calculate the water vapour emission for each batch. The amount of water vapour produced was significantly correlated to the water consumption of the pigs and reached an average of 1 732 g per pig per day. This amount is 36% greater than the reference used for pigs on slatted floors. This value may be used as a reference to calculate the minimum ventilation rate for piggeries with pigs on sawdust deep litters. The amount of compost produced was 19.9 kg per pig with a dry matter content of 44.7%. The amount of nitrogen in the compost was 231 g per pig which is about 50% lower than the reference used for the slurry. The volatile nitrogen emissions are thus much higher from composts than from slurries.