When feed and a liquid are mixed fermentation will spontaneously start. The microbial species dominating in the fermented mixture may vary depending on the environment and/or the ingredients being fermented. However, there is scarce knowledge on this subject. A study was carried out to investigate the biochemical and microbial variations in fermented liquid feed (FLF) samples obtained from 40 Danish farms, which could help in elucidating the reason for the variable results obtained when feeding pigs with FLF. The farms were classified into two groups, a ‘High feed intake’ group and a ‘Low feed intake’ group. The biochemical characteristics and the microbiological composition to group level were determined. Furthermore, characterization of lactic acid bacteria and yeasts to species level was carried out. The biochemical characteristics and the composition of microbial groups of the two farm groups were similar. The data on lactic acid bacteria and yeasts diversity showed that a few phylotypes of lactic acid bacteria (four phylotypes made up 74–79% of the total isolates), and yeasts (four species made up 85–91% of the total isolates), dominated in all samples.

Keywords: Fermented liquid feed; Lactic acid bacteria; Yeasts