Wilting effect on fermentation characteristics and nutritive value of mountain permanent meadow grass silage

Abstract

Grass from a pre-alpine permanent meadow located in the Cansiglio Highland (north Italy) was ensiled immediately after harvesting (T00), and after 5 h (T05) and 26 h (T26) of wilting. Two types of experimental silos were used to assess the chemical characteristics and the evolution of fermentation processes in pre-wilted silages: 500 L capacity silos (S500), opened after 6 months, and 2 L mini-silos (S002), opened at different times after ensiling (0, 12, 24, 48, 96 and 192 h). The forages ensiled in S500 silos were also fed to sheep in order to assess their digestibility and palatability. Dry matter (DM) concentration of fresh grass increased with wilting from 303 to 568 g/kg, while the concentration of other nutrients was scarcely affected by pre-wilting. Fermentation characteristics were significantly modified by wilting with an increase in pH (from 3.82 to 4.33) and a concurrent reduction in fermentation activity. All the fermentation end-products significantly decreased in the wilted silages: lactic acid decreased from 51.6 to 13.1 g/kg DM. Wilting did not affect the extent of fermentation losses. The fermentation processes in the short term were influenced by wilting with a slower development taking place in the wilted silages. The dry matter digestibility and the nutritive values of wilted silages were higher than those of unwilled silages (dDM: 0.52 in TOO to 0.58 in T26 silages), while voluntary intake of DM was not modified by wilting. (© Elsevier/ Inra).