Production Responses of Weaner Pigs after Chronic Exposure to Airborne Dust and Ammonia
2002
Nine hundred and sixty weaner pigs were exposed for 5½ weeks to controlled concentrations of
airborne dust and ammonia in a single, multi-factorial experiment. Production and health responses were
measured. The treatments were a dust concentration of either 1.3, 2.7, 5.1 or 9.9 mg m-3 (inhalable fraction)
and an ammonia concentration of either 0.7, 10.0, 18.8 or 37.0 ppm, which are representative of commercial
conditions. The experiment was carried out over 2½ years and pigs were used in eight batches, each
comprising five lots of 24 pigs. Each treatment combination was replicated once and an additional control
group (nominally ˜ 0 mg m-3 dust and ˜ 0 ppm ammonia) was included in each batch to provide a baseline.
For the other four lots in each batch, the dust concentration was common while all four ammonia
concentrations were used; thus the split-plot design was more sensitive to the effects of ammonia than dust.
The pigs were kept in a purpose-built facility. The pollutants were injected continuously into the air supply. An
artificial dust was manufactured from feed, barley straw and faeces, mixed by weight in the proportions
0.5:0.1:0.4. The ingredients were oven-dried, milled and mixed and then resuspended in the supply air. Dust
concentration was monitored with a tribo-electric sensor, which was calibrated against a TSI aerodynamic
particle sizer and gravimetric samplers. Ammonia was supplied under pressure from a bottle bank and its
concentration was measured with a NOx chemiluminescent gas analyser after catalytic conversion.
Liveweight gain and food intake were measured after 2½ and 5½ weeks of exposure. Exposure to both aerial
pollutants depressed performance by an amount dependent upon dust but not ammonia concentration. Both
food intake and liveweight gain, but not food conversion efficiency, were lower for weaner pigs exposed to 5.1
and 9.9 mg m-3 dust concentration compared with control and 2.5 mg m-3 treatments.
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