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 ร1 ) or PFJ (2.5 ml kg ร1 ). Silages treated with both additives were also made and fermentation quality, in vitro dry matter digestibility and in vitro ruminal NH 3 production were determined. The control silage showed very poor quality with high butyrate and NH 3 -N concentrations. Addition of sucrose signiยฎcantly increased lactate but failed to inhibit the deterioration by clostridial fermentation. Use of PFJ further increased lactate and greatly reduced butyrate and NH 3 -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 NH 3 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 difยฎcult direct cut silage. The potential of improving fermentation may be comparable to conventional sugar additives.