Fungal growth in silages of sugarbeet press pulp and maize

SUMMARY Fungal spoilage of animal feed silage occurs frequently. In spoiled silage of sugarbeet press pulp sampled in The Netherlands during the period 1986–90, 40% of the samples were infested byPenicillium roquefortii. Other fungi of health significance includedAspergillus fumigatus(8% of all samples) andByssochlamysspp. (4 % of all samples). P.roquefortiiis also the dominant spoilage mould in maize silage. However, no PR-toxin could be detected in 25 lumps of P.roquefortii-intested maize silage, although one lump contained a fluorescent substance, with an Rff-value close to that of PR-toxin. This silage sample was not mutagenic, but had a cytotoxic effect towardsSalmonella typhimuriumin the Ames test. All P.roquefortii-infested lumps contained fluorescent fungal metabolites which were absent in samples taken at 5 cm distance from the corresponding lumps in the silage heaps. It is recommended that lumps of fungal-infested silage are removed before feeding the silage to cattle.