Indoor distribution characteristics of airborne bacteria in pig buildings as influenced by season and housing type

OBJECTIVE: A concentration of airborne bacteria generated from swine houses is recognized to be relatively higher than other work places and it is essential to optimally manage it to prevent farmers’ respiratory diseases. This study was conducted to assess the distribution characteristics of airborne bacteria in swine houses located at South Korea. METHODS: A total 27 pig buildings of the enclosed type operated with mechanical ventilation system by a side wall fan and deep-pit manure system with slats were surveyed. Air samples were collected at 1.0 m above the middle floor in pig housing room. A six-stage viable particulate cascade impactor was used to identify the distribution of the sizes of particles in diameter. RESULTS: Seasonal mean levels of airborne bacteria in the housing rooms of gestation/farrowing pigs, nursery pigs and growing/fattening pigs were 3,428(±1,244) colony forming unit (cfu)/m(3), 8,325(±3,209) cfu/m, and 13,254(±6,108) cfu/m(3) for spring; 9,824(±2,157) cfu/m(3), 18,254(±5,166) cfu/m(3), and 24,088(±9,274) cfu/m(3) for summer; 1,707(±957) cfu/m(3), 4,258 (±1,438) cfu/m(3), and 8,254(±2,416) cfu/m(3) for autumn; and 2,322(±1,352) cfu/m(3), 6,124(±1,527) cfu/m(3) and 12,470(±4,869) cfu/m(3) for winter, respectively. CONCLUSION: Concentrations of airborne bacteria according to pig housing type were highest in growing/fattening housing room followed by nursery housing room and gestation/farrowing housing room. In terms of seasonal aspect, the pig building showed the highest levels of airborne bacteria in summer followed by spring, winter and autumn. The respirable airborne bacteria which are ranged between 0.6 and 4.7 μm accounted for approximately 60% compared to total airborne bacteria regardless of pig housing type.