AMMONIA EMISSION PATTERNS DURING THE GROWING PERIODS OF PIGS HOUSED ON PARTIALLY SLATTED FLOORS

The ammonia emission of growing pigs in buildings with partially slatted floors (25% of the pen floor area) was studied to determine its pattern and variation under practical conditions. Five groups of 40 weaned piglets and three groups of 36 fattening pigs were used. Feed and water were available nd libitum. Ammonia concentration and ventilation rate were measured continuously. The mean ammonia emission was found to be 0.87 g/d per rearing pig (range between groups 0.70-1.20 g/d) and 5.8 g/d per fattening pig (range between groups 5.7-5.9 g/d). The results showed a mean daily increase in emission of 30 mg/d per rearing pig and of 85 mg/d per fattening pig. In rearing pigs, emission was 56% higher during the summer period, with a higher ventilation rate and slurry temperature, than during the other periods of the year, but this was not found in fatteners. The ammonia emission was higher during the day than during the night, by 10% (range between groups 5-20%) for piglets and 7% (range between groups 2-12%) for fatteners. Peak emission occurred in the morning for piglets and in the afternoon for fatteners. The daily pattern seemed to be related to the activity of the pigs. After the slurry pit had been emptied and cleaned the ammonia emission remained about 20% lower for 10 h, before regaining its original level. It is concluded that ammonia emission changes significantly during the day and during the growing period and varies between seasons in buildings for growing pigs on partially slatted floors. (C) 1995 Silsoe Research Institute