Storage of small bale silage and haylage - influence of storage period on fermentation variables and microbial composition

An experiment investigating changes in fermentation variables and microbial composition during storage of small-bale silage and haylage was performed. Haylage was defined as silage with a dry-matter (DM) content exceedin.g 500 g kg(-1). Grass was wilted to three different DM contents, and baled into silage (350 g DM kg(-1)), haylage with a low DM content (550 g kg(-1)) and haylage with high DM content (700 g kg(-1)) in small rectangular-shaped bales (0.80 m x 0.48 m x 0.36 m) that were individually wrapped. Bales were stored for short (2 months) or long (14 months) periods before opening and sampling. Silage had higher concentrations of fermentation products and a lower pH than either of the two haylage types. In general, long-term storage influenced all fermentation variables except concentrations of butyric acid and succinic acid, and yeast counts were higher after 14 months than 2 months of storage. However, silage changed in more fermentation variables during storage than the two haylage types. Although differences between short- and long-term stored silage were found, linear correlations between short- and long-term stored bales were present for all chemical variables. Pearson's correlation coefficients were highest for lactic acid, followed by pH.