The Influence of Silage Additives Supplementation on Chemical Composition, Aerobic Stability, and In Vitro Digestibility in Silage Mixed with Pennisetum giganteum and Rice Straw

The purpose of the current research was to evaluate the influence of lactic acid bacteria and cellulase supplementation on the chemical composition, fermentation parameters, aerobic stability, microbial count, and in vitro nutrients digestibility of silage prepared with Pennisetum giganteum and rice straw. This study consisted of four treatments: a control group with no additive supplementation (CON), a lactic acid bacteria supplementation group (LAB), a cellulase supplementation group (CEL), and a combined supplementation group (LAC). After ensiling for 60 d, the chemical composition, fermentation parameters, microbial count, and aerobic stability were determined. Additionally, ruminal fermentation characteristics were evaluated by an in vitro incubation technique. Compared with CON silage, the quality of LAB and CEL silages was enhanced to a certain degree. Combined supplementation with lactic acid bacteria and cellulase in mixed silage of Pennisetum giganteum and rice straw noticeably increased (p < 0.05) the dry matter, crude protein, and lactic acid contents, whereas it reduced (p < 0.05) the pH and ammonia nitrogen/total nitrogen as well as the neutral detergent fiber and acid detergent fiber concentrations. The lactic acid bacteria count in LAC silage was higher (p < 0.05) than that of CON silage, whereas an opposite trend of yeast, aerobic bacteria, and mold was observed between the two groups. The aerobic stability time, in vitro crude protein, and neutral detergent fiber digestibility in LAC silage were significantly increased (p < 0.05) compared with those in CON silage. Moreover, the in vitro ruminal ammonia nitrogen content was reduced (p < 0.05), and the microbial protein and propionic acid concentrations were increased (p < 0.05) in silage after combined inoculation with additives. Taken together, the quality of Pennisetum giganteum and rice straw mixed silage can be improved by inoculation with lactic acid bacteria and cellulase, and combined supplementation shows the greatest improvement in silage quality.