Effects of Different Cutting Stages and Additives on the Fermentation Quality and Microbial Community of Sudangrass (Sorghum sudanense Stapf.) Silages

Abstract

(1) Background: Previous studies have indicated that ferulic acid esterase (FAE), cellulase and xylanase have synergistic effects in lignocellulose degradation, and the cutting stage has a major impact on silages. Whether these additives affect the silages at different cutting stages is unclear. (2) Methods: Sudangrass height at the tested cutting stages was 1.8 m (S1) and 2.0 m (S2). The silage from the two cutting stages was treated with FAE-producing Lactobacillus plantarum (LP), cellulase and xylanase (CX) and a combination of LP and CX (LP+CX) for 30 and 60 days. (3) Results: Compared with CK, adding LP+CX significantly decreased the pH and the content of neutral detergent fiber (NDF) and acidic detergent fiber (ADF) (p < 0.05) and increased the lactic acid (LA) concentration (p < 0.05), dry matter (DM) content and crude protein content. Adding LP+CX effectively degraded lignocellulose in sudangrass, and the NDF and ADF degradation rates at the two stages were all more than 30%. In comparison, cutting at the S2 stage led to a lower pH and higher LA and DM contents (p < 0.05). Additives and the cutting stage exerted a strong effect on the silage microbial community, and Firmicutes and Lactiplantibacillus became the most dominant bacterial phyla and genera, especially at the S2 stage. (4) Conclusions: The results suggest that FAE-producing L. plantarum, cellulase and xylanase had synergistic effects on sudangrass silages, especially at the S2 stage, and their use can thus serve as an efficient method for ensiling.

Synergistic effects of ferulic acid esterase‐producing lactic acid bacteria, cellulase and xylanase on the fermentation characteristics, fibre and nitrogen components and microbial community structure of Broussonetia papyrifera during ensiling

“…The combined use of LAB and enzymes (LP + CE + XY) yielded a significantly greater DM content (P < 0.05) than the other treatments (except for the LP group on day 3 and the LP + XY group on days 3, 7 and 30), which was similar to the results of a previous study. 4 Moreover, the mean DM content of the LP + CE + XY group was significantly greater than that of the other treatment groups, and that of the LP + XY group was also significantly greater than that of the CK groups and the groups treated with one of the additives alone (P < 0.05). The above-mentioned results also confirmed the synergistic effect among FAE-producing LAB, XY and CE.…”

“…The FAEproducing LAB used in this study were screened previously, and a detailed description was published in a previous study. 4 CE and XY are commercial enzymes, and their enzyme activities were 50 and 20 U mg −1 , respectively.…”

“…In addition, high concentrations of propionic acid were detected in some of the treatment groups, which was also observed in a previous study. 4 In particular, the higher propionic acid concentrations observed in the LP addition groups (LP, LP + CE, LP + XY, and LP + CE + XY) might be due to the higher concentration of lactic acid, which can be converted to acetic and propionic acids under anaerobic conditions by some undesirable bacteria. 27 During ensiling, the propionic acid concentration began to decrease in the LP addition treatment groups starting on day 30, which could be attributed to the suppression of undesirable bacteria.…”

“…The above-mentioned results also indicated that FAE-producing L. plantarum, CE and XY have synergistic effects on B. papyrifera silages and can efficiently degrade lignocellulose and provide additional substrates for LAB fermentation. 4,12 The dynamics of organic acids (lactic, acetic, butyric and propionic acids) during the ensiling of B. papyrifera are shown in Table 2. Lactic acid is the most important substance that can decrease the silage pH and improve silage quality.…”

“…2 Ensiling can reduce and soften fibres in the presence of cellulolytic additives, increase the feeding value and resolve issues related to the preservation of feed. 3,4 However, the low content of water-soluble carbohydrate (WSC) and high buffer energy lead to difficulty in preparing high-quality silage of B. papyrifera, 1,5 in addition to its high contents of lignocellulose and fibre polymers. 6 Previous studies have indicated that lignocellulose consists mainly of cellulose, hemicellulose, lignin and some other components.…”