Abstract
Pigs weaned for five days had caecal contents with significantly lower osmolalities than those of unweaned animals of the same age. Supplementation of a standard weaning diet with therapeutic levels of oxytetra-cycline to suppress the normal large intestinal microbial flora did not significantly further reduce osmolality of caecal contents after weaning. This observation suggests that microbial activity in the large intestine may not be sufficiently developed by five days after weaning to have a major influence on absorptive processes at that site. Incomplete development of the large intestinal microflora may be one more factor which acts to predispose the young pig to diarrhoea after weaning.