Comparative evaluation of laboratory-scale silages using standard glass jar silages or vacuum-packed model silages

BACKGROUND: The objective of this study was to compare the fermentation variables of laboratory-scale silages made in glass preserving jars (GLASS) and vacuum-packed plastic bags (Rostock model silages, ROMOS). Silages were prepared from perennial ryegrass (fresh and wilted, 151 g kg(-1) and 286 g kg(-1) dry matter (DM), respectively) and remoistened coarsely ground rye grain (650 g kg(-1) DM) either with or without the addition of a lactic acid bacteria inoculant (3 x 105 colony forming units (cfu) g(-1), LAB). Quintuplicate silos were opened on days 2, 4, 8, 49 and 90. RESULTS: Silage pH (P = 0.073), acetic acid content (P = 0.608) and ethanol content (P = 0.223) were not influenced by the ensiling method. The contents of DM (P < 0.001) and propionic acid (P = 0.008) were affected by the ensiling method, but mean differences were only marginal. In ROMOS the concentration of lactic acid was increased (P = 0.007) whereas butyric acid was produced less (P = 0.001) when compared to GLASS. This suggested slightly better ensiling conditions for ROMOS. CONCLUSIONS: ROMOS represents a reasonable alternative to glass jar silages and opens the possibility for further investigations, e. g. studying the impact of packing density as well as the quantitative and qualitative analysis of fermentation gases. (C) 2010 Society of Chemical Industry