Characterization of two lactic acid bacteria and their influence on silage fermentation of napiergrass

Enterococcus faecium R5-1 (EF) and Lactobacillus plantarum N30-6 (LP) isolated from silages were identified and their influence on silage fermentation of napiergrass (Pennisetum purpureum Sch.) harvested at various times of sunny day were studied. Strain LP had stronger growth ability, acid tolerating capacity and wider fermentable carbohydrates than strain EF. Napiergrass was cut at 0800, 1300 and 1800 h on a sunny day and inoculated with strains EF and LP at 5 log cfu g-1. The concentrations of dry matter, water soluble carbohydrates and the ratio of lactic acid to acetic acid (LA/AA) were higher (P<0.05) and ammonia-N (NH3-N), acetic acid concentrations and silage pH were lower (P<0.05) for uninoculated silages made of napiergrass cut at 1300 and 1800 h compared with that cut at 0800 h. Silage inoculated with LP and EF had lower (P<0.05) NH3-N and acetic acid concentrations and higher (P<0.05) LA/AA than uninoculated silage made with napiergrass cut at 1300 and 1800 h. The EF-inoculated could not improve fermentation quality of silage made with napiergrass cut at 0800 h, which had higher (P<0.05) NH3-N and acetic acid concentrations than uninoculated silage. In conclusion, delayed cutting napiergrass at end of a sunny day was associated with better fermentation quality, and the silages inoculated with EF or LP further improved fermentation quality.