The effect of inoculation and additives on D(-)- and L(+)-lactic acid production and fermentation quality of guineagrass (Panicum maximum Jacq) silage

Two experiments were carried out to study the influence of storage time, gl ucose and urea additions (Experiment 1) and lactic acid bacteria inoculatio n with and without glucose addition (Experiment 2) on the production of lac tate isomers and fermentation quality of guineagrass (Panicum maximum Jacq) silage. All silages in both experiments were well preserved, as indicated by lower pH and little or no butyric acid. In Experiment 1, addition of glu cose or urea did not significantly affect the pH of silages (P>0.05). Urea addition tended to reduce acetic acid content and greatly increased NH3-N c ontent. L-(+)-Lactic acid was produced predominantly in the first 3 days of ensiling, but D(-)-lactic acid increased gradually until 1 month after ens iling. Thereafter all silages became stable. In Experiment 2, inoculation o f Lactobacillus casei or L rhamnosus with or without glucose reduced D(-)-l actic acid and increased L(+)-lactic acid of silages. The proportions of L( +)-lactic acid in these silages were higher than 80% of total lactic acid. L plantarum alone or in combination with glucose promoted D(-)-lactic acid production and decreased the proportion of L(+)-lactic acid. Glucose additi on alone tended to reduce the proportion of L(+)-lactic acid in both experi ments. (C) 2000 Society of Chemical Industry.