Laboratory evaluation of previously fermented juice as a fermentation stimulant for lucerne silage

The potential use of forage juice anaerobically stored for 2 days (previously fermented juice, PFJ) as a silage additive was investigated. Lucerne (450 g) was ensiled in laboratory-scale silos (900 ml capacity) with or without sucrose (20 g kg^-1) or PFJ (2.5 ml kg^-1). Silages treated with both additives were also made and fermentation quality, in vitro dry matter digestibility and in vitro ruminal NH₃ production were determined. The control silage showed very poor quality with high butyrate and NH₃-N concentrations. Addition of sucrose significantly increased lactate but failed to inhibit the deterioration by clostridial fermentation. Use of PFJ further increased lactate and greatly reduced butyrate and NH₃-N production during storage. The combination of sucrose and PFJ was more effective in improving fermentation than either additive on its own. In vitro digestibility appeared to be higher when lucerne was well preserved. Ruminal NH₃ production in vitro was decreased in silages with sucrose and PFJ added at ensiling. This result indicates that use of PFJ can be a promising way to stimulate lactate production in some difficult direct cut silage. The potential of improving fermentation may be comparable to conventional sugar additives.