Effects of combined treatment of lactic acid bacteria and cell wall degrading enzymes on fermentation and composition of Rhodesgrass (Chloris gayana Kunth.) silage

This experiment was conducted to study the effects of lactic acid bacteria (LAB) inoculation either alone or in combination with cell wall degrading enzymes on the fermentation characteristics and chemical compositions of Rhodesgrass silage. Over to 1 kg of fresh Rhodesgrass sample a treatment of inoculant LAB with or without addition of an enzyme of Acremoniumcellulase (A) or Meicelase (M) or a mixture of both enzymes (AM) was applied. The treatments were control untreated, LAB-treated (application rate 1.0 x 10(5) cfu/g fresh sample), LAB + A 0.005%, LAB + A 0.01%, LAB + A 0.02%, LAB + M 0.005%, LAB + M 0.01%, LAB + M 0.02 %, LAB + AM 0.005%, LAB + AM 0.01%, and LAB + AM 0.02%. The sample was ensiled into 2-L vinyl bottle silo, with 9 silages of each treatment were made. Three silages of each treatment were incubated at 20, 30 and 40 degrees C for 2-months of storage period. All silages were well preserved with their fermentation quality has low pH values (3.91-4.26) and high lactic acid concentrations (4.11-9.89 %DM). No differences were found in fermentation quality and chemical composition of the control untreated silage as compared to the LAB-treated silage. Combined treatment of LAB+cellulases improved the fermentation quality of silages measured in terms of lower (p < 0.01) pH values and higher (p < 0.05) lactic concentrations than those of LAB-treated silages. Increasing amount of cellulase addition resulted in decrease (p < 0.05) of pH value and increase (13 < 0.05) of lactic acid concentration. LAB + cellulase treatments (all cellulase types) reduced (p < 0.01) NDF, ADF and in vitro dry matter digestibility of silages compared with the control untreated silages. The fermentation quality and the rate of cell wall reduction were higher (p < 0.01) in the silages treated with LAB + cellulase -A than in the silages treated with either LAB + cellulase M or LAB + cellulase AM. Incubation temperature of 40 degrees C was likely to be more appropriate environment for stimulating the fermentation of Rhodesgrass silages than those of 20 and 30 degrees C.