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Emerging results

E. coli and coliform persistence profiles in dairy faeces under field relevant conditions have been derived for Spring, Summer, Autumn and Winter in 2012 & 2013 in Scotland. Contrasting profiles have also been derived in faecal material protected from rainfall and exposed to warmer and more humid conditions. Data are currently being analysed to determine seasonal & year-on-year variability in E. coli persistence profiles in this faecal matrix.

The research spans two consecutive years to provide a repeat of four seasonal experiments. The rationale was to assess the potential for year-on-year variability in E. coli regrowth and die-off because of shifts in seasonal climatic variables such as temperature and rainfall. The repeat of the seasonal experiment proved valuable as the two year period of study has so far captured some contrasting environmental conditions. Spring 2012 included an unseasonably hot week-long period followed by freezing conditions (a drop in temperature of 27oC). In contrast spring 2013 was extremely cold and wintery, with March 2013 being one of the coldest on record in the UK, and was preceeded by the 2nd wettest UK summer ever recorded. Interestingly, a milder spell during mid-April 2013 saw dramatic increases in E. coli CFUs, particularly in faecal material protected from rainfall and exposed to more humid conditions – clear signals of the role of warmth in promoting cell persistence.

In addition to the derivation of a series of persistence profiles, the project is building up a record of seasonal, inter-annual and within-herd variability of E. coli concentrations in freshly deposited dairy faeces for central Scotland. Findings from this phase of the study have now been published (see publications tab).

A cross comparison study exploring the persistence profiles of E. coli in dairy faeces as determined by culture and molecular-based approaches has also been undertaken. Cell counts observed using selective media have been recorded in parallel with outputs derived by quantitative polymerase chain reaction (qPCR). A manuscript is currently being prepared for journal submission.

The data are being used to refine an empirical model that predicts the burden of E. coli on grazed pasture. The regrowth profiles are being embedded into the model code.