Metabolites of Monascus ruber in silages.

A total of 233 silages were examined and found that Monascus ruber was present in 43 samples with counts between 1 x 10(3) and 9 x 10(6) colony-forming units (CFU)/g (mean: 2 x 10(5) CFU/g). Monacolin K(L) and the hydroxy acid monacolin K(A) were detected by liquid chromatography-mass spectrometry in 45 and 50 of 233 samples at levels ranging from 25-15 600 and 28-65 400 microg/kg, respectively. Citrinin was found with high-performance liquid chromatography-fluorescence detection (FLD) in 14 (6%) samples, the concentrations varied between 2.4 and 64.2 microg/kg. The concentrations of citrinin were low and toxic effects are not anticipated. Monacolin K(A) and monacolin K(L) occur frequently and in considerable amounts in silages. These metabolites are believed to influence the metabolic activity of rumen anaerobic fungi resulting in a poorer digestion of crude fibre.