6 / 2025-03-22 16:56:32

Characteristics on the emission and decay of airborne bacteria from cattle source

airborne bacteria,emission testing,decay,laboratory test,Field measurement

6. 动物健康与疾病控制 > （3）现代养殖业的生物安全

A large amount of microorganisms is produced in livestock farming and suspended in the air, becoming airborne, which has drawn a wide concern of the public. This study investigated the farm-level distribution and emission intensity of airborne bacteria (AB) in a commercial dairy farm to analyze its emission characteristics. AB from cattle source was artificially generated and released into an environmental control chamber to study the influence of the coupling effect of air temperature (T), relative humidity (RH) and ultraviolet radiation (UV) on the decay under laboratory simulation conditions. Results showed that the emission intensity of airborne bacteria was about 606±380 CFU·head^-1s^-1 and mainly distributed on the particle size of 1.1-4.7 μm. The measured average decay rate was 0.029±0.025%·s^-1 in the laboratory experiments. Under the calm wind conditions investigated in this study, the physical deposition effect on the decay of AB was limited, and its contribution was about 10%. When the variation range was 5-35℃ in T, 30%-90% in RH, and 5-25 W m^-2 in UV, the decay of AB from cattle sources was mainly affected by the microbial decay effect. The decay rate of AB increases with the increase of UV intensity and decreased firstly then increased with the increase of RH. The lowest decay was measured in the combination of 25 ℃ in T and 70% in RH. Results of this study would help the precise biosafety prevention in cattle farms and deepen the understanding of AB to the public.