Buffers between grazing sheep and leafy crops augment food safety

Bruce R. Hoar, Edward R Atwill, Lesa Carlton, Jorge Celis, Jennifer Carabez, Tran Nguyen

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


The presence of livestock in or near fresh-market vegetable fields has raised concerns about the potential for contaminating produce with pathogenic bacteria. To develop buffer zones for grazing near production of leafy greens, we assessed the prevalence of Escherichia coli O157:H7 and Salmonella species in sheep that were grazed on alfalfa fields during the winter in California's Imperial Valley. We found E. coli O157:H7 in 1.8% of fecal samples and 0.4% of soil samples, and Salmonella in 0.8% of fecal samples and 0.4% of soil samples. Our results indicate that sheep grazing on alfalfa in the Imperial Valley have a low prevalence of these pathogens in their feces and that these bacteria are rarely found in soil from fields with grazing sheep. The California Leafy Green Products Handler Marketing Agreement guideline of 30 feet between grazing lands or domestic animals and the crop edge is adequate to minimize potential contamination of nearby crops.

Original languageEnglish (US)
Pages (from-to)104-109
Number of pages6
JournalCalifornia Agriculture
Issue number2
StatePublished - Apr 2013

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Plant Science
  • Forestry


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