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Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 4/29/2011 Publication Date: 10/3/2011 Citation: Dungan, R.S., Leytem, A.B., Bjorneberg, D.L. 2011. Concentrations of airborne endotoxin and microorganisms at a 10,000 cow open-freestall dairy. Journal of Animal Science. 89:3300-3309. Interpretive Summary: Confined animal production systems produce elevated bioaerosol concentrations, which are a potential respiratory health risk to individuals on site and downwind. In this study, airborne endotoxin and microorganisms were collected during the spring, summer, and fall at a large open-freestall dairy in southern Idaho. Compared to the background ambient atmosphere, both endotoxin and bacteria concentrations were up to several-hundred fold greater 50 m downwind from the facility, then decreased to near background concentrations at 200 m. However, downwind fungi concentrations were not elevated above background concentrations. Although the bioaerosol concentrations did not follow a seasonal trend, they did significantly correlate with meteorological factors. Increasing temperature was found to be positively correlated with increasing endotoxin, bacteria, and fungi concentrations, while an inverse relationship occurred between the concentration and solar radiation. The airborne concentrations at 50 m downwind were also found to be greatest at night, which can likely be attributed to changes in animal activity and wind speed and reduced exposure of the airborne microorganisms to ultraviolet radiation. Understanding the effect of meteorological conditions and dairy management practices upon bioaerosol emissions is important for gauging offsite transport and developing mitigation strategies. Technical Abstract: Confined animal production systems produce elevated bioaerosol concentrations, which are a potential respiratory health risk to individuals on site and downwind. In this study, airborne endotoxin and microorganisms were collected during the spring, summer, and fall at a large open-freestall dairy in southern Idaho. Compared to the background ambient atmosphere, both endotoxin and culturable heterotrophic bacteria concentrations were up to several-hundred fold greater 50 m downwind from the facility, then decreased to near background concentrations at 200 m. However, downwind fungi concentrations were not elevated above background concentrations. At 50 m downwind, the average inhalable endotoxin concentration ranged from 4.6 to 4243 endotoxin units/cubic meter of air, while bacteria concentrations ranged from 102 to 104 colony forming units (CFU)/cubic meter. Although the bioaerosol concentrations did not follow a seasonal trend, they did significantly correlate with meteorological factors. Increasing temperature was found to be positively correlated with increasing endotoxin, bacteria, and fungi concentrations, while an inverse relationship occurred between the concentration and solar radiation. The airborne concentrations at 50 m were also found to be greatest at night, which can likely be attributed to changes in animal activity and wind speed and reduced exposure of the airborne microorganisms to ultraviolet radiation. |
