ABSTRACT

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), Penicillium/Aspergillus, A fumigatus, and 11 human pathogenic bacteria (e.g. Klebsiella pneumonia) were quantified by qPCR while endotoxins and dust particles were, respectively, measured by LAL assays and with a DustTrak^TM 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 Penicillium/Aspergillus and dust particles. SW method led on day 5 to the lowest concentration of bacteria and Penicillium/Aspergillus, 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 Penicillium/Aspergillus and dust particles. A significant difference was observed between concentration of airborne bacteria, Penicillium/Aspergillus 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.

Implications: 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.

摘要

在奶牛场使用新鲜粪便生产的回收粪便固体 (RMS) 在用作垫料之前需要进行消毒。然而，堆肥 RMS 对空气质量的影响仍然未知。在试验室中桩的 10 天老化期间测试了四种 RMS 堆肥方法：静态堆肥 (SW)、转向堆肥 (TW)、SW 转鼓堆肥 24 小时 (DC24) 或 SW 转鼓堆肥 72 小时 (DC72 ）。在第 0 天（RMS 起球）、第 5 天和第 10 天，使用 SASS®3100 干式空气采样器收集空气样本。细菌（16S rRNA 基因）、青霉/曲霉、烟曲霉和 11 种人类致病菌（例如肺炎克雷伯菌） ) 通过 qPCR 进行量化，而内毒素和灰尘颗粒分别通过 LAL 分析和 DustTrak 进行测量^TM DRX 气溶胶监测仪。在第 0 天，SW 和 TW 产生的 RMS 产生最低浓度的空气传播细菌，而 DC24 产生最低水平的青霉/曲霉和灰尘颗粒。SW 方法在第 5 天导致细菌和青霉/曲霉的浓度最低，而 DC24 和 DC72 导致空气中粉尘的浓度最低。在第 10 天，SW 和 TW 桩与最低水平的青霉/曲霉和灰尘颗粒相关。观察到空气传播细菌、青霉菌/曲霉的浓度之间存在显着差异TW 桩周转之前和期间的内毒素。在空气样本中未检测到任何研究的人类病原体。本研究的结果表明，就微生物空气质量而言，SW 和 TW 是生产堆肥 RMS 的最有前途的方法。然而，实验室并不能准确地代表商业奶牛场，有必要对这些堆肥方法进行进一步研究。最后，该研究强调垫料及其管理可能是奶牛舍空气质量的决定性因素。

影响: 该研究评估了由新鲜牛粪产生的堆肥回收粪便固体 (RMS) 对微生物空气质量的影响。RMS 在用作动物的垫料之前需要进行堆肥或消毒。RMS对动物健康的影响仍有待证实，而对空气质量和奶农健康的影响尚不清楚。在本研究中，研究了与四种 RMS 堆肥方法相关的微生物空气质量。数据显示，两种方法导致灰尘颗粒、内毒素、霉菌和细菌的气溶胶化程度较低。