Effects of wilting and mechanical conditioning on proteolysis in sanfoin (Onobrychis viciifolia Scop) wilted erbage and silage.

Ensiling legumes allows conservation of high-quality forage. However, severe protein degradation occurs during ensiling of legumes. A field study was carried out in 1999 on sainfoin (Onobrychis viciifolia Scop) to investigate the effects of wilting and mechanical conditioning on proteolysis in wilted herbage and silage. The herbage was cut with both a rubber roll conditioning machine (C) and with a mower without conditioner (U). It was wilted in the field to three dry matter (DM) levels (220, 330 and 440 g kg-1) and ensiled in laboratory glass silos. The herbages and the silages were analysed for ensilability characteristics, fermentation quality and nitrogen fractions. During wilting the non-protein nitrogen (NPN) values increased (p < 0.05) in both U and C treatment. The free amino acid (free AA) values increased (p < 0.05) from 2.4 to 12.9 and from 2.4 to 7.2 mol kg-1 total nitrogen, in the U and C treatments, respectively. Low wilted silages (DM content <320 g kg-1) underwent butyric acid fermentation and extensive proteolysis in both treatments, with lower (p < 0.05) NPN and free AA values in the C treatment. Mechanical conditioning may limit protein breakdown and catabolism of some essential amino acids by reducing the field wilting time in both sainfoin wilted herbage and silage.