Effects of cellulase and xylanase on fermentative profile, bacterial diversity, and in vitro degradation of mixed silage of agro-residue and alfalfa

Abstract

The objective was to determine effects of cellulase, xylanase, and commercial fibrolytic enzymes on fermentation quality, aerobic stability, bacterial community, and in vitro degradation of mixed silages. Mixtures of alfalfa, wheat bran, and rice straw [80:15:5 on a fresh matter (FM) basis] were ensiled for 1, 3, 5, 7, 15, 30, and 45 d after treatment with: distilled water (control, C); cellulase (E); xylanase (X); or commercial fibrolytic enzymes (EX), with all enzyme preparations applied at 100 U/g FM. The 45-day silages were subjected to an in vitro degradation test. Each of the three enzyme-treated groups enriched relative abundance (RA) of Lactobacillus, Weissella, and Stenotrophomonas maltophilia, increased water soluble carbohydrate (WSC) concentrations, and extended aerobic stability over 384 h, but concurrently inhibited growth of undesirable microbes (i.e., Acinetobacter sp, Lelliottia amnigena, and Sphingomonas sp), reducing pH and concentrations of ammonia nitrogen (AN), butyric acid (BA) and propionic acid (PA). Compared to C, adding X or EX increased the RA of L. paralimentarius and L. parabrevis, enhanced accumulation of acetic acid (AA) and crude protein (CP), and reduced hemicellulose content. Furthermore, E group silage had the highest abundance of W. cibaria. In addition, EX enriched RA of Bacillus velezensis, reduced AN concentration, increased DM degradability, total VFA production, and gas production during in vitro incubation. In conclusion, addition of X or EX enhanced ensiling by enhancing concentrations of AA; however, EX was the most promising enzyme, based on reducing AN concentration and increasing DM content and DM degradability. Graphical Abstract

Lactic Acid Bacteria and Cellulase Improve the Fermentation Characteristics, Aerobic Stability and Rumen Degradation of Mixed Silage Prepared with Amaranth and Rice Straw

“…In the current study, the NDF and ADF contents were obviously reduced in the mixed silage inoculated with cellulase. A previous study found that supplementation of cellulase decreased the NDF and ADF contents of alfalfa, wheat-bran and rice-straw mixed silage [29], which is consistent with our study. Overall, the combination of lactic acid bacteria and cellulase in mixed silage displayed the maximum DM and CP contents and the minimum NDF content, indicating that the treatments with the two additives combined were more effective in improving the nutritive value of amaranth and rice-straw mixed silage.…”