Effects of mechanical forage treatment and surfactants on fermentation of grass silage

Three silage experiments were conducted in Uppsala, Sweden, with the objective of determining the physical impact of different harvesting machines on the forage and on silage fermentation. Experiments were also conducted to investigate whether the application of water or a solution of surfactants to cut or long grass could compensate for the lack of released cell contents and lead to a fermentation pattern comparable to that of precision-chopped (PC) forage. Forage chopped by different machines to almost equal median particle length (23-29 mm) produced silage of very different quality, probably because of different degrees of tissue disruption. Forage chopped in a cutter head (CUT) of by a forage wagon (FW) resulted in silage with high clostridial activity and low lactic acid formation in contrast to PC forage, which produced high quality silage without butyric acid. An increase in silage density from 107 to 182 kgDM m(-3) increased lactic acid formation and lowered pH but did not reduce clostridial activity. The application of water or a surfactant solution to cut or long, pie-wilted forage had no effect on silage fermentation. Unchopped, high dry matter forage responded to an inoculation with 2 x 10(6) lactic acid bacteria (LAB) g(-1) with a significantly faster and higher formation of lactic acid compared with uninoculated forage.