Managemental influences on the selective proliferation of two strains of haemolyticEscherichia coliin weaned pigs

Abstract

SUMMARYIn an experimental study on a piggery it was found that haemolyticEscherichia coliof O-scrotypes 138 or 139 proliferated in the intestinal tracts of pigs following weaning, withE. coliof the 0-138 typo also being occasionally recovered from unwearied pigs, and onco from a sow. Organisms of the O-138 typo produced heat labile enterotoxin and their presence in weaned pigs was associated with the development of severe post-weaning diarrhoea.E. coliof O-130 type produced a vero cell cytotoxin and were associated with a milder diarrhoea in weaned pigs. Under various managemental circumstances the O-138 typeE. colialmost invariably proliferated after weaning. The O-139 strain ofE. colidid however proliferate rather than the O-138 strain following the movement of weaned pigs to new accommodation, after weaned pigs were returned to their sow and then weaning again 5 days later, and very occasionally in pigs weaned at 5 weeks of ago. In all theso cases earlier proliferation of the O-138E. colihad been detected, suggesting that this may be a prerequisite for proliferation of the O-130 strain.