Coliform numbers in the stomach and small intestine of healthy pigs following weaning at three weeks of age.

In 60 weaned and 52 unweaned pigs, aged between 21 and 32 days, the number of coliform organisms in the gastric contents was found to be related to their pH value. The contents were generally more acidic in the weaned animals and contained fewer coliforms. Haemolytic coliform organisms were never identified among selected isolates examined from the gastric contents although in weaned animals the haemolytic enterotoxigenic Escherichia coli serotype 0149: K91, K88a,c (Abbotstown strain) was commonly recovered from the intestines. After weaning, this strain appeared to colonize the anterior small intestine from lower down the tract, and its presence was associated with an increase in the total coliform count at the site from which it was isolated. Rotaviruses were also more commonly detected in the intestinal contents of weaned than unweaned pigs, but their appearance after weaning appeared to be preceded by the proliferation of haemolytic E. coli. The presence of either or both of these potentially enteropathogenic organisms never induced diarrhoea, and although faecal water content increased significantly after weaning, this occurred independently of the presence of both agents.