Effect of fermentation and bacterial inoculation on lucerne cell walls

Abstract

Changes were found in the cell wall composition of lucerne after ensiling at three different dry matter (DM) contents. The amount of protein associated with cell walls was reduced during ensiling, regardless of inoculation level, by 46–68%, whereas protein associated with the lignin residue was reduced to a lesser extent (< 40%). The effect ofensiling on individual sugars of the cell wall varied. Uronics of the cell wall were decreased by 12% with wilted silages (290 g DM kg^–1) but were unchanged in a higher dry matter silage (401 g DM kg^–1) and silages with a limited pH change during ensilage. The arabinose and galactose contents, as a fraction of cell walls, decreased (15–24%), increasing glucose and xylose contents proportionally. Inoculation decreased arabinose and galactose contents early in the fermentation when the pH decline was enhanced but final values were not significantly different (P > 0.32). Removal of the sugars from the cell wall appears to be related to pH because silages with little pH change had no change in the cell wall sugars and inoculation reduced the cell wall sugars only after silage pH declined.