Comparative Study on the Effects of Combined Treatments of Lactic Acid Bacteria and Cellulases on the Fermentation Characteristic and Chemical Composition of Rhodesgrass (Chloris gayana Kunth.) and Italian Ryegrass (Lolium multiflorum Lam.) Silages

Prior to ensiling Rhodesgrass (RG) and Italian ryegrass (lRG) were treated with lactic acid bacteria (LAB) or with LAB+cellulases to compare their fermentation characteristics and chemical compositions. LAB (Lactobacillus casei) was added to all ensiling materials (except the untreated control) of RG and IRG at a concentration of $1.0{\times}10^5\;cfu.g^{-1}$ fresh forage. The enzymes used were Acremoniumcellulase (A), Meicelase (M) or a mixture of both (AM). Each enzyme was applied at levels of 0.005, 0.01 and 0.02 % of fresh forage. The silages with each treatment were incubated at 20, 30 and $40^{\circ}C$ and stored for about 2 months. While no marked differences were found between the RG and IRG silages with various treatments on dry matter (DM), volatile basic nitrogen (VBN) and water soluble carbohydrate (WSC) contents, there were significant differences in pH value, and lactic acid and butyric acid contents. LAB inoculation did not affect the fermentation characteristics of either the RG or IRG silages. The combined treatments of LAB+cellulases improved the fermentation quality of both the RG and IRG silages as evidenced by the decrease in pH value and increase in lactic acid content. Increasing the amount of added cellulase resulted in a decrease in pH value and an increase in lactic acid content in both the RG and IRG silages. Cellulases A and AM had a greater effect than cellulase M on the fermentation quality of the RG and IRG silages. Incubation temperatures of 30 and $40^{\circ}C$ appeared to be more appropriate environments for stimulating good fermentation than $20^{\circ}C$.