An investigation into the sources of lactic acid bacteria in grass silage

Abstract

During the 1983 silage making season an investigation was carried out to determine the contribution made by farm machinery to the numbers of lactic acid bacteria present on grass. Although no lactic acid bacteria were isolated from the standing crop, up to 103/g were found in the grass as it entered the clamp. Examination of machinery in close contact with the grass revealed lactic acid bacteria on the mower blades and on the forks of the rough‐terrain vehicle used to pack the grass into the clamp. During the 1984 season the occurrence of lactic acid bacteria in particular batches of grass from the standing crop through to silage after 2 d in the clamp was studied. There was a gradual increase in numbers of lactic acid bacteria in the grass during the process of mowing and collection. Wilting resulted in a greater initial increase in numbers but non‐wilted silage had the highest count after 48 h. The majority of organisms isolated from machinery before silage making were streptococci. After silage making the number and proportions of organisms changed, with numbers increasing in all cases, particularly from the mower with lactobacilli and streptococci predominating which indicates that passage through the machinery served to inoculate the grass.