U.S. Meat Animal Research Center, Agricultural Research Service, U.S. Department of Agriculture, P.O. Box 166, State Spur 18D, Clay Center, Nebraska 68933, USA.
J Food Prot. 2013 Aug;76(8):1308-21. doi: 10.4315/0362-028X.JFP-12-364.
Reducing Escherichia coli O157:H7 in livestock manures before application to cropland is critical for reducing the risk of foodborne illness associated with produce. Our objective was to determine the fate of naturally occurring E. coli O157:H7 and other pathogens during minimally managed on-farm bovine manure composting processes. Feedlot pen samples were screened to identify E. coli O157:H7-positive manure. Using this manure, four piles of each of three different composting formats were constructed in each of two replicate trials. Composting formats were (i) turned piles of manure plus hay and straw, (ii) static stockpiles of manure, and (iii) static piles of covered manure plus hay and straw. Temperatures in the tops, toes, and centers of the conical piles (ca. 6.0 m(3) each) were monitored. Compost piles that were turned every 2 weeks achieved higher temperatures for longer periods in the tops and centers than did piles that were left static. E. coli O157:H7 was not recovered from top samples of turned piles of manure plus hay and straw at day 28 and beyond, but top samples from static piles were positive for the pathogen up to day 42 (static manure stockpiles) and day 56 (static covered piles of manure plus hay and straw). Salmonella, Campylobacter spp., and Listeria monocytogenes were not found in top or toe samples at the end of the composting period, but E. coli O157:H7 and Listeria spp. were recovered from toe samples at day 84. Our findings indicate that some minimally managed composting processes can reduce E. coli O157:H7 and other pathogens in bovine manure but may be affected by season and/or initial levels of indigenous thermophilic bacteria. Our results also highlight the importance of adequate C:N formulation of initial mixtures for the production of high temperatures and rapid composting, and the need for periodic turning of the piles to increase the likelihood that all parts of the mass are subjected to high temperatures.
在将牲畜粪便施用于农田之前减少大肠杆菌 O157:H7 的含量对于降低与农产品相关的食源性疾病风险至关重要。我们的目的是确定在最小化管理的农场牛粪便堆肥过程中，自然发生的大肠杆菌 O157:H7 和其他病原体的命运。从饲料棚中筛选出大肠杆菌 O157:H7 阳性粪便。使用这种粪便，在两个重复试验中，每个试验构建了三种不同堆肥方式的每个四个堆。堆肥方式为：（i）翻动的粪便加干草和稻草堆，（ii）静态的粪便堆，和（iii）覆盖的静态粪便加干草和稻草堆。监测锥形堆（每个约 6.0 m3）顶部、脚趾和中心的温度。每两周翻动一次的堆肥堆在顶部和中心达到高温的时间比静态堆肥堆长。在第 28 天和之后，从翻动的粪便加干草和稻草堆的顶部样本中未回收大肠杆菌 O157:H7，但从静态堆肥堆的顶部样本中可回收该病原体，直至第 42 天（静态粪便堆肥）和第 56 天（静态覆盖的粪便加干草和稻草堆）。在堆肥结束时，在顶部和脚趾样本中未发现沙门氏菌、弯曲杆菌属和单核细胞增生李斯特菌，但在第 84 天从脚趾样本中回收了大肠杆菌 O157:H7 和李斯特菌属。我们的研究结果表明，一些最小化管理的堆肥过程可以减少牛粪便中的大肠杆菌 O157:H7 和其他病原体，但可能受到季节和/或初始土著嗜热细菌水平的影响。我们的研究结果还强调了初始混合物中适当的 C:N 配方对于产生高温和快速堆肥的重要性，以及定期翻动堆肥的必要性，以增加堆肥质量的所有部分都能达到高温的可能性。
