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Cattle Feedlot Soil Moisture and Manure Content: II. Impact on Escherichia coli O157
Author(s) -
Berry Elaine D.,
Miller Daniel N.
Publication year - 2005
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2005.0656
Subject(s) - manure , feedlot , water content , soil water , escherichia coli , moisture , zoology , compost , agronomy , biology , chemistry , ecology , biochemistry , geotechnical engineering , organic chemistry , gene , engineering
ABSTRACT The moisture and manure contents of soils at cattle feedlot surfaces vary spatiotemporally and likely are important factors in the persistence of Escherichia coli O157 in these soils. The impacts of water content (0.11–1.50 g H 2 O g −1 dry feedlot surface material [FSM]) and manure level (5, 25, and 75% dry manure in dry FSM) on E. coli O157:H7 in feedlot soils were evaluated. Generally, E. coli O157:H7 numbers either persisted or increased at all but the lowest moisture levels examined. Manure content modulated the effect of water on E. coli growth; for example, at water content of 0.43 g H 2 O g −1 dry FSM and 25% manure, E. coli O157:H7 increased by 2 log 10 colony forming units (CFU) g −1 dry FSM in 3 d, while at 0.43 g H 2 O g −1 dry FSM and 75% manure, populations remained stable over 14 d. Escherichia coli and coliform populations responded similarly. In a second study, the impacts of cycling moisture levels and different drying rates on naturally occurring E. coli O157 in feedlot soils were examined. Low initial levels of E. coli O157 were reduced to below enumerable levels by 21 d, but indigenous E. coli populations persisted at >2.50 log 10 CFU g −1 dry FSM up to 133 d. We conclude that E. coli O157 can persist and may even grow in feedlot soils, over a wide range of water and manure contents. Further investigations are needed to determine if these variables can be manipulated to reduce this pathogen in cattle and the feedlot environment.