Improving the quality of Napier grass silage with pyroligneous acid: Fermentation, aerobic stability, and microbial communities

Inoculation of Lactobacillus parafarraginis enhances silage quality, microbial community structure, and metabolic profiles in hybrid Pennisetum

BACKGROUND

This study investigated the effects of inoculating Lactobacillus parafarraginis alone or in combination with citric acid on the silage quality, microbial community structure, and metabolic characteristics of hybrid Pennisetum. The experiment included three treatments: (1) addition of 10 ml distilled water (CON); (2) addition of 1 × 106 cfu/g L. parafarraginis (LP); (3) addition of 1 × 106 cfu/g L. parafarraginis and 1% citric acid (LCA). The fermentation was maintained at 25 ℃ for 60 days.

RESULTS

The addition of L. parafarraginis increased the dry matter, water-soluble carbohydrates, and crude protein content of the silage and decreased the fiber contents. Moreover, lactic acid content was notably higher, and pH values were lower in the L. parafarraginis group, with higher lactic acid bacteria (LAB) compared with the CON. The microbial community analysis indicated that adding L. parafarraginis promoted the proliferation of beneficial LAB and inhibited spoilage bacteria, such as Clostridium. In the LCA, amino acid metabolism was improved, particularly with an increase in L-tyrosine concentration, along with significant enrichment of pathways related to tryptophan metabolism.

CONCLUSIONS

The addition of L. parafarraginis improved the fermentation quality of the silage, reduced undesirable microorganisms, and increased the content of organic acids, indicating its potential to enhance the flavor of the silage. Compared with individual treatments, the combination of L. parafarraginis and citric acid improved amino acid metabolism and enriched pathways related to tryptophan metabolism, further enhancing the quality of the silage. These findings highlight the potential of L. parafarraginis, especially in combination with citric acid, as an effective additive for producing high-quality, nutritious hybrid Pennisetum silage.

Effects of kinds of additives on fermentation quality, nutrient content, aerobic stability, and microbial community of the mixed silage of king grass and rice straw

To investigate the effects of kinds of additives on silage quality, the mixture of king grass and rice straw was ensiled with addition of sucrose, citric acid and malic acid at the levels of 0, 1 and 2%, being blank control (CK), citric acid groups (CA1, CA2), malic acid groups (MA1, MA2), citric acid + malic acid groups (CM1, CM2), sucrose groups (SU1, SU2), mainly focusing on fermentation quality, nutrient content, aerobic stability and microbial community of the silages. The results showed that the addition of sucrose decreased (p < 0.05) pH and increased the content of water soluble carbohydrate (p < 0.05). The sucrose groups and mixed acid groups also had a lower (p < 0.01) neutral detergent fiber content. The addition of citric acid and the mixed acid increased (p < 0.01) the aerobic stability of the silage, reduced the abundance of Acinetobacter, and the addition of citric acid also increased the abundance of Lactiplantibacillus. It is inferred that citric acid and malic acid could influence fermentation quality by inhibiting harmful bacteria and improve aerobic stability, while sucrose influenced fermentation quality by by promoting the generation of lactic acid. It is suggested that the application of citric acid, malic acid and sucrose would achieve an improvement effect on fermentation quality of the mixed silage.

Bacillus velezensis promotes the proliferation of lactic acid bacteria and influences the fermentation quality of whole-plant corn silage

Objective

This study aimed to investigate the promoting effect of a Bacillus velezensis (BV) strain on lactic acid bacteria (LAB) and determine its influence on the fermentation quality and aerobic stability of silage.

Methods

Flat colony counting method was used to evaluate the effect of BV on the growth of LAB. Freshly harvested whole-plant corn was inoculated separately with BV and L. plantarum (LP), along with an uninoculated control group (CK), and assessed at 1, 3, 5, 7, 15, and 30 days of ensiling.

Results

The results indicated that BV exhibited a proliferative effect on Weissella confusa, Lactobacillus plantarum L-2, and Pediococcus pentosaceus. And exhibited a more rapid pH reduction in BV-inoculated silage compared with that in CK and LP-inoculated silage during the initial stage of ensiling. Throughout ensiling, the BV and LP experimental groups showed enhanced silage fermentation quality over CK. Additionally, relative to LP-inoculated silage, BV-inoculated silage displayed reduced pH and propionic acid. BV also prolonged aerobic stability under aerobic conditions. The microbial community in BV-inoculated silage showed greater stability than that in LP-inoculated silage. Additionally, Firmicutes and Lactobacillus exhibited more rapid elevation initially in BV versus LP-inoculated silage, but reached comparable levels between the two inoculation groups in the later stage.

Conclusion

In summary, BV enhanced the efficacy and aerobic stability of whole-plant corn silage fermentation by stimulating LAB proliferation.

Silage additives improve fermentation quality, aerobic stability and rumen degradation in mixed silage composed of amaranth and corn straw

The objective of this research was to investigate effects of different additives on the fermentation quality, aerobic stability and rumen degradation of mixed silage composed of amaranth and corn straw. The mixture ratio of amaranth to corn straw was 78%: 22%. Three additives were selected in this study and five groups were as follows: control group (CON, without additive), lactic acid bacteria group (LAB, 5 mg/kg, Lactobacillus plantarum ≥ 1.6×1010 CFU/g and L. buchneri ≥ 4.0×109 CFU/g), glucose group (GLU, 30 g/kg), cellulase group (CEL, 2 mg/kg) and lactic acid bacteria, glucose and cellulase group (LGC, added at the same levels as in individual group). The period of ensiling was 60 days. Fermentation quality, chemical composition and aerobic stability of mixed silage were analyzed. Four cows with permanent ruminal fistula were selected as experimental animals. Nylon bag technique was used to study rumen degradation characteristic of dry matter (DM), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) of mixed silage. Compared with CON group, the addition of different silage additives could improve mixed silage quality of amaranth and corn straw to some extent. Combining three additives significantly increased (P < 0.05) the DM, CP and lactic acid contents, whereas decreased (P < 0.05) the ADF and NDF contents as well as pH and ammonia nitrogen/total nitrogen. Moreover, the aerobic stability and rumen degradation of DM, CP and NDF were significantly improved (P < 0.05) in LGC group when compared to other groups. In conclusion, the combined addition of lactic acid bacteria, glucose and cellulase increased DM, CP and lactic acid contents as well as lactic acid bacteria count, decreased NDF and ADF contents and aerobic bacteria and mold counts, improved aerobic stability and rumen degradation of amaranth and corn straw mixed silage.