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Some observations on aerobic deterioration in untreated silages and in silages made with formaldehyde‐containing additives
Author(s) -
Barry Thomas N.,
Di Menna Margaret E.,
Webb Paul R.,
Parle John N.
Publication year - 1980
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740310204
Subject(s) - silage , anaerobic exercise , aerobic bacteria , fermentation , chemistry , food science , formaldehyde , bacteria , compaction , zoology , materials science , biology , biochemistry , composite material , physiology , genetics
Aerobic deterioration of untreated silage and of silage made with formaldehyde‐containing additives (FCA) was studied in seven trials in which large stacks were self‐fed by cattle. Heating and deterioration on prolonged exposure to air was a problem in some silages made with FCA. It was concluded that the main factors which predisposed these silages to heat were restriction of anaerobic fermentation by the additives, a high pH of 4.7‐5.4 and, in three trials, inadequate compaction. In the additive‐treated stacks, which showed aerobic deterioration, a zone of elevated temperature developed on the stack top surface. With time this moved to a layer 20‐40 cm from the surface, where it remained. The surface layer (0‐15 cm) then cooled, its pH rose to 8.5 and a mould flora developed. Both the onset of heating and the rise in pH were related to counts of aerobic bacteria; neither parameter was consistently related to yeast counts. A ten‐fold increase in mould counts was associated with each one unit increase in pH. It is suggested that acid‐tolerant aerobic bacteria (perhaps assisted by yeasts in some instances) caused the first stage of aerobic deterioration, namely the onset of heating and the rise in pH, and that invasion by moulds then followed as a second stage of the deterioration process. Diminished oxygen tensions in the well compacted lower parts of the stacks appeared responsible for restriction of the heating zone to a depth of 40 cm from the stack top surface.