Survival of Escherichia coli in cowpats in pasture and in laboratory conditions.
OBJECTIVE
To compare survival of Escherichia coli and faecal coliforms (FC) in bovine faeces deposited in a pasture or incubated in a controlled laboratory environment at temperatures within the same range.


RESULTS
Faecal samples from three cow herds were deposited as shaded and nonshaded cowpats in a field and incubated in a laboratory for one month at 21.1, 26.7 and 32.2 degrees C. Both FC and E. coli concentrations increased as much as 1.5 orders of magnitude both in the field and in the laboratory during the 1st week and subsequently decreased. In shaded cowpats, the die-off of E. coli and FC was significantly slower, and the proportion of E. coli in FC was significantly larger as compared with nonshaded cowpats. The die-off was faster in the field than in the laboratory at similar temperatures.


CONCLUSIONS
FC and E. coli die-off rates were substantially lower in laboratory conditions than in the field within the same range of temperatures.


CONCLUSIONS
This study underscores the importance of field data on survival of manure-borne FC and E. coli, and indicates that laboratory die-off rates have to be corrected to be used for field condition simulations.
Van Kessel
J S
JS
Environmental Microbial Safety Laboratory, USDA-ARS, Beltsville, MD 20705, USA.
Pachepsky
Y A
YA
Shelton
D R
DR
Karns
J S
JS
D000818:Animals; D002417:Cattle; D015169:Colony Count, Microbial; D004755:Enterobacteriaceae / Q000254:growth & development / Q000302:isolation & purification; D004926:Escherichia coli / Q000254:growth & development / Q000302:isolation & purification*; D005243:Feces / Q000382:microbiology*; D005260:Female; D008297:Male; D008372:Manure / Q000382:microbiology*; D012988:Soil Microbiology; D013048:Specimen Handling / Q000379:methods; D013696:Temperature; D014867:Water / Q000032:analysis
D008372:Manure; D014867:Water