Use of competitive exclusion to control enterotoxigenic strains of Escherichia coli in weaned pigs
2005
Mortality and morbidity associated with Escherichia coli cause economic losses to the swine industry. Enterotoxigenic strains of E. coli affecting nursery-age pigs have become more difficult to treat because of increased antibiotic resistance, and alternatives to antibiotics are currently being sought. Our laboratory developed a defined culture of commensal bacteria of porcine gastrointestinal tract origin, maintained it in continuous-flow culture for 3 yr, and designated it as RPCF. Laboratory studies have shown that RPCF-treated pigs had decreased mortality and bacterial shedding compared with controls when challenged with enterotoxigenic strains of E. coli. The objective of the present study was to evaluate the practicality, safety, and efficacy of RPCF to protect nursery-age pigs in commercial swine operations from field challenge by enterotoxigenic strains of E. coli. In field studies involving six geographically separated farms with a history of high mortality from K-88 and F-18 strains of E. coli, piglets were administered RPCF within 24 h of birth and monitored throughout the nursery period. A total of 21,467 piglets were treated with RPCF, and a similar number of piglets on the same farms served as untreated controls. On five of six farms, mortality in RPCF-treated pigs decreased by an average of 2.6% compared with untreated pigs. Differences in mortality were not observed in RPCF-treated pigs compared with controls on one Minnesota farm. When projected to an annual basis, the economic benefits from decreased medication costs and mortality averaged $24,663 per farm. These studies suggest that under commercial conditions, RPCF tended to control disease induced by enterotoxigenic E. coli, and that RPCF may be a viable alternative to the use of antibiotics.
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