The objective of this study was to obtain knowledge about the postnatal development of microflora and the production of short-chain fatty acids in 24 piglets suckled by sows and 26 piglets fed on milk replacement. On day 14 piglets which had received no colostrum had higher counts of Enterobacteriaceae (p < 0.001) and coliform bacteria (p <0.001) in the jejunum contents than piglets suckled by their mother sow. Depending on age, concentrations of both lactic and acetic acid were higher in the contents of the small intestine of piglets suckled by sows compared to milk replacer-fed piglets. Replacement of maternal milk by artificial feeding adversely affected the postnatal development of the piglets. This resulted in higher morbidity and mortality in those piglets.