Animal feeds (n = 226), collected from pastures or feeding troughs on UK farms and from feed manufacturers' bulk stores, were analysed for Escherichia coli harbouring shiga-toxin genes (stx), faecal coliforms, coliphages and stx-harbouring bacteriophages.Methods and Results
Samples comprised of 79 fresh grasses, 26 silages and 121 dried or heat-processed feeds (DPF). Five of the 79 (6·3%) fresh grass samples contained stx2-E. coli. stx-E. coli were not detected in the silages or DPF that were examined. Faecal coliforms were detected in 75/79 (94·9%) of fresh grasses, 19/26 (73·1%) of silages and 36/121 (29·8%) of processed feeds. Coliphages were detected in 63/79 (79·7%) and 18/26 (69·2%) of fresh grasses and silages, respectively. Coliphages were isolated at a significantly lower prevalence of 5% (6/121) from processed feeds. Although stx2-phage was isolated from the enrichment of a single grass sample, stx-phages were not detected in any of the silage or processed feeds. We did not detect stx1-phage in any of the samples collected.Conclusions
Pastures have the potential to act as transmission vectors for stx-harbouring E. coli for grazed livestock.Significance and Impact of the Study
This is the first study to report on the prevalence of E. coli harbouring stx genes, faecal coliforms, coliphages and stx-harbouring bacteriophages in a range of feedstuffs destined for consumption by UK livestock. This study provides information on the risk of feeds to the spread of stx-phages between livestock and/or the environment.