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Keywords:

  • bacterial reduction;
  • environment;
  • manure;
  • O157;
  • Shiga toxin-producing E. coli;
  • survival;
  • verocytotoxigenic E. coli

Abstract

Aims:  To determine the fate of Escherichia coli deposited onto grassland via faeces, from naturally colonized cattle, sheep or pigs.

Methods and Results:  Groups of cattle, sheep and pigs were penned outdoors on grass during November, and removed after 14 days. Escherichia coli populations in the ground declined over 134 days from initial average levels of 5·34, 4·31 and 4·96 log10 CFU g−1 in cattle, sheep and pig pens, respectively. The maximum Escherichia coli survival time was up to 162 days (190 days taking sampling interval and deposition time into account), but numbers varied significantly amongst the 20 replicates taken each day. Escherichia coli originating from cattle and sheep had average decimal reduction times (D-values) of 38 and 36 days, respectively; E. coli originating from pigs declined significantly faster (average D-value of 26 days).

Significance and Impact of the Study: Escherichia coli from livestock faeces can survive on grass for at least 5–6 months, affording opportunity for pathogenic biotypes to contaminate animals, plants or water.