|Wells, James - Jim|
|Kalchayanand, Norasak - Nor|
|GUERINI, MICHAEL - Former ARS Employee|
Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/27/2013
Publication Date: 8/1/2013
Citation: Berry, E.D., Millner, P.D., Wells, J., Kalchayanand, N., Guerini, M.N. 2013. Fate of naturally occurring Escherichia coli O157:H7 and other zoonotic pathogens during minimally managed bovine feedlot manure composting processes. Journal of Food Protection. 76(8):1308-1321.
Interpretive Summary: Cattle manure containing E. coli O157:H7 can be a source of the organism to contaminate produce and water when this manure is used to fertilize crops. Composting the manure is one technique to reduce E. coli O157:H7 and other pathogens before its use as fertilizer. Composting is a controlled biological decomposition process used to manage organic waste materials such as animal manure, sewage sludge, household wastes, or yard waste. Typically, organic waste materials are mixed and placed in a pile. If the mixture and composting conditions are favorable, the compost pile heats to high temperatures which can inactivate pathogens. The objective of this study was to investigate the ability of different minimally managed on-farm cattle manure composting processes to reduce naturally occurring E. coli O157:H7 in cattle manure. Composting process treatments included: (1) turned piles of manure-hay/straw mixtures, (2) static piles of manure, and (3) unturned piles of covered manure-hay/straw mixtures. Compost piles that were turned every two weeks reached higher temperatures for longer periods in the tops and centers than piles that were left unturned. Our findings indicate that some minimally managed composting processes can reduce E. coli O157:H7 in bovine manure and that periodic turning of the piles to increase the likelihood that all parts of the mass are subjected to high temperatures is important for more effective and rapid elimination of pathogens.
Technical Abstract: 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.