Fungal growth in silages of sugarbeet press pulp and maize

Abstract

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 by Penicillium roquefortii . Other fungi of health significance included Aspergillus fumigatus (8% of all samples) and Byssochlamys spp. (4 % of all samples). P. roquefortii is 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 Rf f -value close to that of PR-toxin. This silage sample was not mutagenic, but had a cytotoxic effect towards Salmonella typhimurium in 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.