Journal of the Society of Agricultural Structures, Japan

Outbreak of animal infectious diseases damages not only animal production but also the entire regional economy. It is necessary to raise the level of biosecurity in animal farms as to produce safe animal products. And It is necessary to reduce microbe concentration in livestock houses as much as possible in order to reduce disease risk. Therefore, the present study was carried out to elucidate the relationship between aerosol concentration and airborne microbe concentration in enclosed weaning pig houses in order to aim to develop estimation method of airborne microbe concentration with aerosol that can be measured in real time as a index. In addition, we established the gene quantification analysis of PCV2 and PRRSV, we examine the relation of pathogenic microorganisms concentration and aerosol concentration. As a result, the strong correlation between aerosol concentration and viable airborne microbe concentration was found in the aerosol particle size more than 5.0 μm. And, as for pathogenic microorganism concentration, PCV2 was below the detection limit even in the specimen either during the measurement period. However, PRRSV was detected 0.132 TCID₅₀/m³ from air samples and 0.138 TCID₅₀/m³ from oral fluid in October 3 when aerosol concentration was the highest during measurement period. It was examined that there were some correlation between aerosol concentration and PRRSV concentration.

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We examined the use of rapeseed oil in place of fossil diesel to assess the feasibility of expanding cultivated areas of rapeseed crops in Japan. Our previous report described a test run to 1 500 h with a simply modified diesel generator. That engine test was done for 1 250 h using straight rapeseed oil and 250 h using fossil diesel. Finally, the engine was tested for an additional 1 100 h: 1 000 h using straight rapeseed oil and 100 h using fossil diesel. The maintenance of filters and injection nozzles was conducted intermittently during testing. After 1 555 h running, the engine began to emit white smoke. The fuel consumption increased. The incident resulted from grimed injection nozzles. It recovered after replacement with new nozzles. Upon disassembly of the engine after 2 600 h operation, thick soot was found on the cylinder head, inlet valves, and outlet valves. Checking those valves is recommended for long-term operation. Comparison tests of new nozzles revealed that the Elsbett nozzle showed a better spraying profile than a genuine one. Furthermore, Elsbett nozzles showed better performance than genuine ones during an engine starting test with rapeseed oil. A fuel comparison test for rapeseed oil and fossil diesel was held under griming engine conditions: low-load and low-engine speed. Soot adhering to the nozzle has different shapes according to the fuels, but judging the better one is difficult. The generator consumed more rapeseed oil than fossil diesel hourly because the net calorific value of rapeseed oil is lower than that of fossil diesel. Engine oil analysis revealed that more lubricant constituents were consumed during operation with rapeseed oil, probably because the uneven rotation of the engine increased friction under low-load and low-speed conditions.

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