Production of composted recycled manure solids from a Canadian dairy farm: Impact on microbial air quality in experimental conditions
Creators: name: Duquette-Lozeau, Karine
name: Létourneau, Valérie
name: Lemieux, Joanie
name: Fournel, Sébastien
name: Côté, Caroline
name: Godbout, Stéphane
name: Duchaine, Caroline
Publisher: name: Taylor & Francis
Year: 2021
Subjects: subject: Space Science
subject: 59999 Environmental Sciences not elsewhere classified
subject: FOS: Earth and related environmental sciences
subject: FOS: Earth and related environmental sciences
subject: 39999 Chemical Sciences not elsewhere classified
subject: FOS: Chemical sciences
subject: FOS: Chemical sciences
subject: Ecology
subject: FOS: Biological sciences
subject: FOS: Biological sciences
subject: Immunology
subject: FOS: Clinical medicine
subject: FOS: Clinical medicine
subject: 69999 Biological Sciences not elsewhere classified
subject: Inorganic Chemistry
subject: 110309 Infectious Diseases
subject: FOS: Health sciences
subject: FOS: Health sciences

description: Recycled manure solids (RMS) produced in dairy farms from fresh manure need to be sanitized before using them as bedding material. However, the impact on air quality of composting RMS remains unknown. Four RMS composting methods were tested during a 10-day aging of piles in experimental chambers: static windrow (SW), turned windrow (TW), SW following drum composting for 24 h (DC24) or SW following drum composting for 72 h (DC72). Air samples were collected using a SASS®3100 Dry Air Sampler on days 0 (pilling of the RMS), 5, and 10. Bacteria (16S rRNA genes), <i>Penicillium/Aspergillus, A fumigatus</i>, and 11 human pathogenic bacteria (e.g. <i>Klebsiella pneumonia</i>) were quantified by qPCR while endotoxins and dust particles were, respectively, measured by LAL assays and with a DustTrak<sup>TM</sup> DRX Aerosol Monitor. On day 0, RMS produced by SW and TW yielded the lowest concentrations of airborne bacteria, while DC24 resulted in the lowest levels of <i>Penicillium/Aspergillus</i> and dust particles. SW method led on day 5 to the lowest concentration of bacteria and <i>Penicillium/Aspergillus</i>, and DC24 and DC72 to the lowest concentration of airborne dust. On day 10, SW and TW piles were associated with the lowest levels of <i>Penicillium/Aspergillus</i> and dust particles. A significant difference was observed between concentration of airborne bacteria, <i>Penicillium/Aspergillus</i> and endotoxins before and during the turnover of TW piles. None of the studied human pathogens was detected in the air samples. Results of the present study suggest that SW and TW are the most promising methods for the production of composted RMS with respect to microbial air quality. However, the experimental chambers do not accurately represent commercial dairy barns and further research on these composting methods is necessary. Finally, the study highlights that bedding material and its management may be determinant factors for air quality in dairy barns. <i>Implications</i>: The research evaluated the impact on microbial air quality of composting recycled manure solids (RMS) produced from fresh cow manure. RMS need to be composted or sanitized before using them as bedding material for animals. The impact on animal health of RMS still needs to be confirmed, while the effect on air quality and the health of dairy farmers is unknown. In the present study, microbial air quality associated with four RMS composting methods was investigated. Data revealed that two methods resulted in lower aerosolization of dust particles, endotoxins, molds, and bacteria.