Aerosols and Bacteria Concentration in Different Types of Japanese Dairy Milking Houses

摘要

In order to elucidate the effects of housing types on aerosols and bacteria concentration, the aerosols and bacteria concentration were measured in an enclosed type dairy milking free stall house and an open type free barn milking house. Aerosol concentrations was measured by Optical Particle Sizer (OPS). Aerobacterias were collected using a Coriolis fi Air Sampler. The samples then inoculated into medium for detection of Staphylococcus aureus, Escherichia coli and total Aerobic bacteria. The averageconcentration of particle sizes 0.3-0.5 [im, 0.5-1.0 fim, 1.0-2.0 nm, 2.0-5.0 /im and 5.0-10.0 /im in the enclosed house were 7.96, 6.94, 5.97, 5.76, 4.91 logioparticles/m3, respectively and in the open house were 7.84, 6.75, 5.85, 5.71, 5.11 logio particles/m3, respectively. There was no significance difference of aerosols concentration (p>0.05) between enclosed house and open house. The average concentration of Staphylococcus aureus, Escherichia coli and total Aerobic bacteria in enclosed house were2.04, 0.04, 2.91 logio cfu/m3, respectively and in open house were 2.87, 0.76, 3.96 logio cfu/m3, respectively. There was a 1% significant difference for Staphylococcus aureus (p<0.01), 5% for Escherichia coli (p<0.05) and 1% for Aerobic bacteria (p<0.01) between enclosed house and open house. The difference of bacteria concentration between enclosed and open houses were due to difference of airflow within the houses (p<0.01). In enclosed and open houses there was no correlation between aerosol concentration and bacteria concentration.