Microbial community and fermentation characteristic of Italian ryegrass silage prepared with corn stover and lactic acid bacteria

The potential of biogas production and effects of alfalfa silage under the synergistic influence of Lactobacillus acidophilus and Rosa roxburghii pomace waste on the fermentation quality and bacterial community

The process of ensiling serves as a dual-purpose technique, functioning as a means of preserving biomass for biogas production while serving as a biological pretreatment method with the potential for little fermentation loss. In this study, we investigate the potential of Rosa roxburghii pomace (RP) and Lactobacillus acidophilus to improve the biomass preservation of biogas produced from alfalfa during anaerobic storage. Coinoculation of RP and Lactobacillus acidophilus resulted in better preservation of nutrients (biomass), with a significant increase of 47.38% within the lactic acid content and a notable decline of 40.34% in the ammonia nitrogen content relative to those in the control treatment. Moreover, coinoculation of RP and Lactobacillus acidophilus resulted in an elevated proportion of Lactobacillus, and the species Lactiplantibacillus plantarum dominated anaerobic fermentation. The synergistic effect of RP and Lactobacillus acidophilus continuously stimulated anaerobic fermentation, leading to 33.33% and 23.17% increases in methane production and acetate content, respectively, after 72 h of coinoculation with RP and Lactobacillus acidophilus compared to the control treatment. Overall, coinoculation of RP and Lactobacillus acidophilus offers an attractive opportunity to increase methane production from fruit waste while reducing costs and synergistically integrating with other pretreatment techniques to optimize the methane generation potential.

IMPORTANCE

Considering the increasing global energy demand and urgent environmental issues, exploring prospective resources for bioenergy production is imperative. However, the biomass of legume perennials may serve as an inexpensive and stable source of clean energy for modern society due to its wide availability and broad range of sources. In addition, the combination of RP and Lactobacillus acidophilus application increased the abundance of Lactobacillus, inhibited the growth of Kosakonia, and promoted anaerobic fermentation, which had beneficial synergistic effects on biomass retention and biogas production in alfalfa samples. Coinoculation improvements with RP and Lactobacillus acidophilus observed here are expected to reduce costs associated with CH4 conversion bioprocesses and increase CH4 production.

Effects of different concentrations of Lactiplantibacillus plantarum and Bacillus licheniformis on silage fermentation parameter, chemical composition and microbial community of Pennisetum sinese

The purpose of the experiment was to study the effects of different concentrations of Lactiplantibacillus plantarum (LP) and Bacillus licheniformis (BL) on the quality of Pennisetum sinese (PS) silage. The experiment consisted of seven treatment groups. The control group did not use additives, and the experimental groups were added with LP or BL of 1 × 105 CFU/g fresh weight (FW), 1 × 106 CFU/g FW and 1 × 107 CFU/g FW, respectively. The nutritional value of Pennisetum sinese silage was comprehensively evaluated using CNCPS 6.5 system and 16sDNA sequencing technology. The results showed that the ammonia nitrogen content and pH of each experimental group were significantly lower than those of the control group (p < 0.05). The starch content gradually decreased and the water-soluble carbohydrate (WSC) content increased in both LP and BL groups with the increase of addition concentration. The LP7 group could significantly increase the true protein content in protein (p < 0.05), and CP in BL groups decreased gradually with the increase of concentration. Compared with the control group, the content of neutral detergent fiber (NDF) and acid detergent fiber (ADF) was significantly lower in LP7 group (p < 0.05) and the ADF content was significantly lower in BL5 group (p < 0.05). In addition, LP and BL were able to change the proportion of each component in CNCPS system for Pennisetum sinese silage. The use of LP and BL can reduce the relative abundance of harmful microorganisms in silage such as Sediminibacterium and Nitrospira, and significantly change the microbial community structure in silage (p < 0.05). In conclusion, LP and BL have significant effects on silage quality and nutritional value. The nutritional value of Pennisetum sinese in LP groups showed a dose-dependent effect, and adding 1 × 107 CFU/g LP have the best effect in silage. The best effect was achieved by adding 1 × 105 CFU/g BL in BL groups, and the effect of LP7 group was better than that of BL5 group.

Ensiling characteristics, in vitro digestibility and bacterial community structure of mulberry leaf silage with or without the addition of cellulase, protease, and starch

Objective

This study aimed to investigate the effects of cellulase, protease, and starch on the fermentation quality, in vitro digestibility, and microbial community of mulberry leaf silage after 30d of ensiling.

Methods

Mulberry leaves (376 g/kg dry matter (DM)) were ensiled with four experimental treatments: i) CON, no additives; ii) CEL, added cellulase (120 U/g fresh matter [FM]); iii) CPR, added cellulase (120 U/g FM) and protease (50 U/g FM); and iv) CPS, added cellulase (120 U/g FM), protease (50 U/g FM), and starch (2% FM).

Results

All treatments with additives improved fermentation quality, showing higher DM (353 ~ 378 vs. 341 g/kg DM), lactic acid (LA) content (51.6 ~ 64.6 vs. 40.2 g/kg DM), lactic acid bacteria (LAB) counts (7.63 ~ 7.73 vs. 7.49 log10 CFU /g of FM), along with lower pH values (4.29 ~ 4.60 vs. 5.09), and DM losses (124 ~ 130 vs. 134 g/kg DM) compared to the CON group. All the additive treated groups showed higher in vitro digestibility of DM (698 ~ 720 vs. 618 g/kg DM), in vitro digestibility of NDF (395 ~ 412 vs. 336 g/kg DM), and ADF (277 ~ 298 vs. 232 g/kg DM) than CON. Among all the groups, the CPS group exhibited the highest DM content (378 g/kg DM), LA content (64.6 g/kg DM) and LAB counts (7.73 log10 CFU /g of FM), with the lowest pH value (4.29) and DM losses (124 g/kg DM). Additionally, the additive treatments increased abundance of bacteria like Firmicutes and Enteroccocus, while reducing Proteobacteria abundance, and resulted in lower diversity and richness of the microbial community. Specifically, CPR and CPS silages showed increased Pediococcus and decreased Enterobacter compared to CON and CEL, and CPS silage had a relatively high abundance of favorable Bacteroidota. Furthermore, the CPS silage exhibited upregulated genetic functions, energy and lipid metabolism, as well as metabolism of cofactors and vitamins compared to the other groups.

Conclusion

The combined application of cellulase, protease, and starch effectively improved the fermentation quality, in vitro digestibility, and microbial community of mulberry leaf silage over the 30-day ensiling period.

Forage quality and fermentation dynamics of silages of Italian ryegrass (Lolium multiflorum Lam.) wilted for varying periods

OBJECTIVE

This trial was conducted to explore the impact of different wilting time of Italian ryegrass (IRG) in the field on the nutritional quality and fermentation characteristics of its silage.

METHODS

The harvested IRG was directly wilted in the field for 0 day (W0), 1 day (W1), 2 days (W2), and 3 days (W3), respectively, and tedded every 6 hours. And the preserved IRG was sampled at 1, 2, 3, 5, 10, 20, 30, and 45 days after ensiling and three replicates per treatment.

RESULTS

With the extension of wilting, the dry matter (DM) content and pH value of wilted IRG gradually increased (p<0.05). There was a downward trend in; neutral detergent fiber (NDF), acid detergent fiber (ADF), and hemicellulose with the increase of wilting time, but only W2 and W3 were significantly different from W0 (p<0.05). Crude protein (CP), in vitro DM digestibility), total digestible nutrients (TDN), and relative feed value decreased significantly with the increase of wilting time (p<0.05), except for W1. After 45 days of ensiling, W1 had the highest CP, TDN, and the lowest ADF and NDF. During ensiling, the increase of acetic acid and the decrease of WSC in W0 and W1 were similar, but the accumulation rate of lactic acid in W0 was faster than that in W1, resulting in the lowest pH value in W0. After 5 days of ensiling, the ratio of lactic acid to acetic acid in W1 stabilized at around 3:1, while W0 kept changing.

CONCLUSION

Italian ryegrass that wilted in the field for 1 day effectively improved the dynamic changes in CP, TDN, ADF, and NDF and fermentation quality of silage. Therefore, in practice, W1 was more recommended in production of IRG silage.

Heterogenetic mechanism in multidimensional pit mud with different fermentation years: From microbial structure dynamic succession to metabolism phenotypes

Pit mud (PM) is fermenting agents in the strong-flavor baijiu (SFB) production. In this paper, the discrepancies in fermentation parameters, microbial community succession patterns and metabolic phenotypes were compared in multidimensional PMs. The results showed that pyruvic acid, succinic acid, S-Acetyldihydrolipoamide-E, glycerol and glyceric acid were the key metabolites responsible for the metabolic differences between the 2-, 30-,100- and 300-year multidimensional PMs, while the butanoic acid, heptyl, heptanoic acid, heptanoic acid ethyl ester, hexanoic acid and octanoic acid were the key differential flavor compounds in the 2-, 30-,100- and 300-year multidimensional PMs. Concurrently, the diversity and abundance of microbial community also exhibited significant differences between the new and old multidimensional PMs, the assembly pattern of bacterial communities changed from deterministic to stochasticity from lower (bottom of the pit and under the huangshui fluid) to upper PM (up the huangshui fluid and top of the pit). Key microorganisms related to the succession process of the lower PM were Clostridium, Methanobacterium, Petrimonas, Lactobacillus, Methanobrevibacter, Bellilinea, Longilinea, Bacillus. In contrast, the upper PM were Caproicibacter, Longilinea, Lactobacillus, Proteinphilum, Methanobrevibacter, Methanobacterium, Methanobacteriaceae, Petrimonas, Bellilinea and Atopobium. Redundancy analysis (RDA) indicated that the key environmental factors regulating the succession of microbial in upper PM were lactic acid, moisture, pH and available phosphorus. In contrast, the lower was lactic acid, acetic acid and ammonia N. Based on these results, heterogeneous mechanisms between new and old multidimensional PMs were explored, providing a theoretical support for improving the quality of new PM.

Changes in microbial dynamics and fermentation characteristics of alfalfa silage: A potent approach to mitigate greenhouse gas emission through high-quality forage silage

Feeding ruminants with high-quality forage can enhance digestibility and reduce methane production. Development of high-quality silage from leguminous plants with lactic acid bacteria can improve digestibility and it mitigate the greenhouse gas emissions. In this study, we developed a high-quality alfalfa silage with improved fermentation index and microbial dynamics using Levilactobacillus brevis-KCC-44 at low or high moisture (LM/HM) conditions and preserved it for 75 or 150 days. Alfalfa fermentation with L. brevis enhances acidification and fermentation characteristics primarily due to the dominance of lactic acid bacteria (LAB) L. brevis (>95%) compared to alfalfa fermented with epiphytic LAB. The inoculant L. brevis improved the anaerobic fermentation indexes resulting in a higher level of lactic acid in both high (10.0 ± 0.12 & 8.90 ± 0.31%DM) and low moisture (0.55 ± 0.08 & 0.39 ±0.0 %DM) in 75 and 150 days respectively, compared to control silage. In addition, the marginal amount of acetic acid (range from 0.23 ± 0.07 to 2.04 ± 0.27 %DM) and a reduced level of butyric acid (range between 0.03 ± 0.0 to 0.13± 02 %DM) was noted in silage treated with LAB than the control. The LAB count and abundance of Levilactobacillus were higher in alfalfa silage fermented with L. brevis. Microbial richness and diversity were reduced in alfalfa silage treated with L. brevis which prompted lactic acid production at a higher level even for a prolonged period of time. Therefore, this L. brevis is an effective inoculant for producing high-quality alfalfa silage since it improves fermentation indexes and provides reproducible ensiling properties.

Effect of soil contamination and additives on fermentative profile, microbial community and iron bioaccessibility of alfalfa silage

Background

During alfalfa harvesting and preservation, it is important to minimize losses and preserve dry matter and nutrients. Soil contamination of alfalfa forage is a common issue that occurs during the ensiling process. Soil contamination can adversely influence the quality of silage, potentially altering the fermentation process, microbial composition, and iron content.

Results

In this study, different levels of soil (0, 1.5% or 7.5% contamination on a wet basis; silt loam soil) and two types of additives (LP, Lactobacillus plantarum inoculant alone; MLP, combination addition of molasses and Lactobacillus plantarum) were added to alfalfa and subjected to anaerobic fermentation for 45 days to evaluate the iron content as well as the alpha diversity and relative abundance of bacterial and fungal communities. Soil-contaminated alfalfa contained lower levels of LA (14.2–41.8 g kg−1 DM) and higher levels of AN (50.0–156.4 g kg−1 DM) compared to uncontaminated alfalfa. Soil contamination of alfalfa forage increased the abundance of Clostridia, Actinobacteria, and Alphaproteobacteria in silage. The application of LP or MLP in soil-contaminated silage increased the abundance of Lactobacillus and inhibited the growth of Enterococcus faecium, Pediococcus pentosaceus, unclassified_f_Enterobacteriaceae, and Weissella cibaria. In addition, as the level of soil contamination increased, both the total and bioaccessible iron contents in alfalfa silage increased. The dominant bacteria Lactobacillus plantarum exhibited a positive relationship with LA and bioaccessible iron contents and a negative relationship with pH, AN and BA. The dominant fungi Neocosmospora rubicola showed a positive relationship with total iron, BA, AN and pH.

Conclusions

Soil contamination of alfalfa increased the abundance of Clostridia, Actinobacteria, and Alphaproteobacteria and it also increased the total and bioaccessible iron content in silage. The addition of LP and MLP improved the fermentation quality of soil-contaminated silage by increasing LA production and reducing the relative abundance of Enterococcus faecium, Pediococcus pentosaceus, unclassified_f_Enterobacteriaceae, and Weissella cibaria.

Graphical Abstract

Epiphytic microbiota source stimulates the fermentation profile and bacterial community of alfalfa-corn mixed silage

The epiphytic microbiota source on plants plays a crucial role in the production of high-quality silage. To gain a better understanding of its contribution, the microbiota of alfalfa (M1C0), corn (M0C1) and the resulting mixture (M1C1) was applied in alfalfa-corn mixed silage production system. M1C0 decreased ammonia-N levels in terms of total nitrogen (57.59-118.23 g/kg TN) and pH (3.59-4.40) values (p < 0.01), which increased lactic acid (33.73-61.89 g/kg DM) content (p < 0.01). Consequently, this resulted in higher residual water-soluble carbohydrate (29.13-41.76 g/kg DM) and crude protein (152.54-167.91 g/kg DM) contents, as well as lower NDF (427.27 g/kg DM) and ADF (269.53 g/kg DM) contents in the silage compared to M1C1- and M0C1-treated samples. Moreover, M1C0 silage showed significantly higher bacterial alpha diversity indices (p < 0.05), including the number of observed species and Chao1 and Shannon diversity indices, at the later stages of ensiling. Lactobacillus, Kosakonia and Enterobacter were the dominant bacterial species in silages, with a relative abundance of >80%. However, the abundance of Lactobacillus amylovorus in M0C1- and M1C1-treated silage increased (p < 0.01) in the late stages of ensiling. These findings confirmed that the epiphytic microbiota source exerts competitive effects during anaerobic storage of alfalfa-corn mixed silage.

Effects of inoculation and dry matter content on microbiome dynamics and metabolome profiling of sorghum silage

Sorghum forage was ensiled for 90 days at two dry matter (DM) contents (27 vs. 39%) without or with Lactiplantibacillus plantarum inoculation. On day 90 of fermentation, silages were sampled to assess the microbial community dynamics and metabolome profile. L. plantarum inoculation improved silage quality, as shown by a lower pH and greater acetic acid concentration. Loss of DM remained unaffected by L. plantarum inoculation but was greater in low- vs. high-DM sorghum silages (14.4 vs. 6.62%). The microbiome analysis revealed that Pseudomonas congelans represented the dominant species of the epiphytic microbiota in both low- and high-DM sorghum forage before ensiling. However, L. buchneri represented the dominant species at the end of ensiling. Ensiling fermentation resulted in distinct metabolic changes in silages with varying DM content. In low-DM silages, ensiling fermentation led to the accumulation of 24 metabolites and a reduction in the relative concentration of 13 metabolites. In high-DM silages, ensiling fermentation resulted in an increase in the relative concentration of 26 metabolites but a decrease in the concentration of 8 metabolites. Compared to non-inoculated silages, L. plantarum inoculation resulted in an increased concentration of 3 metabolites and a reduced concentration of 5 metabolites in low-DM silages. Similarly, in high-DM silages, there was an elevation in the relative concentration of 3 metabolites, while a decrease in 7 other metabolites. Ten metabolites with bio-functional activity were identified, including chrysoeriol, isorhamnetin, petunidin 3-glucoside, apigenin, caffeic acid, gallic acid, p-coumaric acid, trans-cinnamic acid, herniarin, and 3,4-dihydroxy-trans-cinnamate. This study presents a comprehensive analysis of microbiome and metabolome profiling of sorghum forage during ensiling as a function of DM content and L. plantarum inoculation, with a particular emphasis on identifying metabolites that may possess bio-functional properties. KEY POINTS: • DM loss was not different by L. plantarum but higher in low- vs. high-DM silage. • L. buchneri dominated ensiling, regardless of DM level. • 10 metabolites with bio-functional activity were identified.

The influence of low-temperature resistant lactic acid bacteria on the enhancement of quality and the microbial community in winter Jerusalem Artichoke (Helianthus tuberosus L.) silage on the Qinghai-Tibet Plateau

Jerusalem Artichoke (Helianthus tuberosus L.), an emerging "food and fodder" economic crop on the Qinghai-Tibet Plateau. To tackle problems such as incomplete fermentation and nutrient loss occurring during the low-temperature ensilage of Jerusalem Artichokes in the plateau's winter, this study inoculated two strains of low-temperature resistant lactic acid bacteria, Lactobacillus plantarum (GN02) and Lactobacillus brevis (XN25), along with their mixed components, into Jerusalem Artichoke silage material. We investigated how low-temperature resistant lactic acid bacteria enhance the quality of low-temperature silage fermentation for Jerusalem Artichokes and clarify its mutual feedback effect with microorganisms. Results indicated that inoculating low-temperature resistant lactic acid bacteria significantly reduces the potential of hydrogen and water-soluble carbohydrates content of silage, while increasing lactic acid and acetic acid levels, reducing propionic acid, and preserving additional dry matter. Inoculating the L. plantarum group during fermentation lowers pH and propionic acid levels, increases lactic acid content, and maintains a dry matter content similar to the original material. Bacterial community diversity exhibited more pronounced changes than fungal diversity, with inoculation having a minor effect on fungal community diversity. Within the bacteria, Lactobacillus remains consistently abundant (>85%) in the inoculated L. plantarum group. At the fungal phylum and genus levels, no significant changes were observed following fermentation, and dominant fungal genera in all groups did not differ significantly from those in the raw material. L. plantarum exhibited a positive correlation with lactic acid and negative correlations with pH and propionic acid. In summary, the inoculation of L. plantarum GN02 facilitated the fermentation process, preserved an acidic silage environment, and ensured high fermentation quality; it is a suitable inoculant for low-temperature silage in the Qinghai-Tibet Plateau.

Microbial network and fermentation modulation of Napier grass and sugarcane top silage in southern Africa

IMPORTANCE

Feed shortage in the tropics is a major constraint to the production of livestock products such as milk and meat. In order to effectively utilize of local feed resources, the selected lactic acid bacteria (LAB) strain was used to prepare Napier grass and sugarcane top silage. The results showed that the two silages inoculated with LAB formed a co-occurrence microbial network dominated by Lactiplantibacillus during the fermentation process, regulated the microbial community structure and metabolic pathways, and improved the silage fermentation quality. This is of great significance for alleviating feed shortage and promoting sustainable production of livestock.

Ensiled diet improved the growth performance of Tibetan sheep by regulating the rumen microbial community and rumen epithelial morphology

The aim of this study was to investigate the effects of ensiled agricultural byproducts from Qinghai-Tibet plateau on growth performance, rumen microbiota, ruminal epithelium morphology, and nutrient transport-related gene expression in Tibetan sheep. Fourteen male Tibetan sheep were randomly assigned to one of two diets: an untreated diet (without silage inoculum, CON, n = 7) or an ensiled diet (with silage inoculum, ESD, n = 7). The total experimental period lasted for 84 d, including early 14 d as adaption period and remaining 70 d for data collection. The ESD increased average daily gain (P = 0.046), dry matter intake (P < 0.001), ammonia nitrogen (P = 0.045), microbial crude protein (P = 0.034), and total volatile fatty acids concentration (P < 0.001), and decreased ruminal pH value (P = 0.014). The proportion of propionate (P = 0.006) and the copy numbers of bacteria (P = 0.01) and protozoa (P = 0.002) were higher, while the proportion of acetate (P = 0.028) was lower in the sheep fed ESD compared to CON. Pyrosequencing of the 16S ribosomal RNA gene revealed that ESD increased the relative abundance of Firmicutes, Ruminococcus, Lachnospiraceae_AC2044_group, Lachnospiraceae_XPB1014_group, and Christensenellaceae_R-7_group in the rumen (P < 0.05), while decreased the relative abundance of Bacteroidota, Prevotellaceae_UCG-003, and Veillonellaceae_UCG-001 (P < 0.05). Analyses with PICRUSt2 and STAMP indicated that the propionate metabolism pathway was enriched in the sheep fed ESD (P = 0.026). The ESD increased the rumen papillae height (P = 0.012), density (P = 0.036), and surface area (P = 0.001), and improved the thickness of the total epithelia (P = 0.018), stratum corneum (P = 0.040), stratum granulosum (P = 0.042), and stratum spinosum and basale (P = 0.004). The relative mRNA expression of cyclin-dependent Kinase 2, CyclinA2, CyclinD2, zonula occludens-1, Occludin, monocarboxylate transporter isoform 1 (MCT1), MCT4, sodium/potassium pump, and sodium/hydrogen antiporter 3 were higher in the rumen epithelial of sheep fed ESD than CON (P < 0.05). Conversely, the relative mRNA expressions of Caspase 3 and B-cell lymphoma-2 were lower in the sheep fed ESD than CON (P < 0.05). In conclusion, compared with an untreated diet, feeding an ensiled diet altered the rumen microbial community, enhanced nutrient transport through rumen epithelium, and improved the growth performance of Tibetan sheep.

Fermentation characteristics and microbial community composition of wet brewer's grains and corn stover mixed silage prepared with cellulase and lactic acid bacteria supplementation

OBJECTIVE

The objective of this study was to investigate how cellulase or/and lactic acid bacteria (LAB) affected the fermentation characteristic and microbial community in wet brewer's grains (WBG) and corn stover (CS) mixed silage.

METHODS

The WBG was mixed thoroughly with the CS at 7:3 (w/w). Four treatment groups were studied: i) CON, no additives; ii) CEL, added cellulase (120 U/g fresh matter [FM]), iii) LAB, added LAB (2×106 cfu/g FM), and iv) CLA, added cellulase (120 U/g FM) and LAB (2×106 cfu/g FM).

RESULTS

All additive-treated groups showed higher fermentation quality over the 30 d ensiling period. As these groups exhibited higher (p<0.05) LAB counts and lactic acid (LA) content, along with lower pH value and ammonia-nitrogen (NH3-N) content than the control. Specifically, cellulase-treated groups (CEL and CLA) showed lower (p<0.05) neutral detergent fiber and acid detergent fiber contents than other groups. All additives increased the abundance of beneficial bacteria (Firmicutes, Lactiplantibacillus, and Limosilactobacillus) while they decreased abundance of Proteobacteria and microbial diversity as well.

CONCLUSION

The combined application of cellulase and LAB could effectively improve the fermentation quality and microbial community of the WBG and CS mixed silage.

Influences of Growth Stage and Ensiling Time on Fermentation Characteristics, Nitrite, and Bacterial Communities during Ensiling of Alfalfa

This study examined the impacts of growth stage and ensiling duration on the fermentation characteristics, nitrite content, and bacterial communities during the ensiling of alfalfa. Harvested alfalfa was divided into two groups: vegetative growth stage (VG) and late budding stage (LB). The fresh alfalfa underwent wilting until reaching approximately 65% moisture content, followed by natural fermentation. The experiment followed a completely randomized design, with samples collected after the wilting of alfalfa raw materials (MR) and on days 1, 3, 5, 7, 15, 30, and 60 of fermentation. The growth stage significantly influenced the chemical composition of alfalfa, with crude protein content being significantly higher in the vegetative growth stage alfalfa compared to that in the late budding stage (p < 0.05). Soluble carbohydrates, neutral detergent fiber, and acid detergent fiber content were significantly lower in the vegetative growth stage compared to the late budding stage (p < 0.05). Nitrite content, nitrate content, nitrite reductase activity, and nitrate reductase activity were all significantly higher in the vegetative growth stage compared to the late budding stage (p < 0.05). In terms of fermentation parameters, silage from the late budding stage exhibited superior characteristics compared to that from the vegetative growth stage. Compared to the alfalfa silage during the vegetative growth stage, the late budding stage group exhibited a higher lactate content and lower pH level. Notably, butyric acid was only detected in the silage from the vegetative growth stage group. Throughout the ensiling process, nitrite content, nitrate levels, nitrite reductase activity, and nitrate reductase activity decreased in both treatment groups. The dominant lactic acid bacteria differed between the two groups, with Enterococcus being predominant in vegetative growth stage alfalfa silage, and Weissella being predominant in late budding stage silage, transitioning to Lactiplantibacillus in the later stages of fermentation. On the 3rd day of silage fermentation, the vegetative growth stage group exhibited the highest abundance of Enterococcus, which subsequently decreased to its lowest level on the 15th day. Correlation analysis revealed that lactic acid bacteria, including Limosilactobacillus, Levilactobacillus, Loigolactobacillus, Pediococcus, Lactiplantibacillus, and Weissella, played a key role in nitrite and nitrate degradation in alfalfa silage. The presence of nitrite may be linked to Erwinia, unclassified_o__Enterobacterales, Pantoea, Exiguobacterium, Enterobacter, and Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium.

Effects of whole-plant corn and hairy vetch (Vicia villosa Roth) mixture on silage quality and microbial communities

OBJECTIVE

Hairy vetch is considered to improve the nutritional value of corn because of its high protein and mineral levels. To better understand the mechanism underlying hairy vetch regulated whole-plant corn silage fermentation, this experiment investigated the fermentation quality and bacterial community of whole-plant corn and hairy vetch mixture.

METHODS

Whole-plant corn and hairy vetch were mixed at ratios of 10:0 (Mix 10:0), 8:2 (Mix 8:2), 6:4 (Mix 6:4), 4:6 (Mix 4:6), 2:8 (Mix 2:8), and 0:10 (Mix 0:10) on a fresh weight basis. After ensiling 60 days, samples were collected to examine the fermentation dynamics, ensiling characteristics, and bacterial communities.

RESULTS

Mix 0:10, Mix 2:8, and Mix 4:6 showed poor fermentation characteristics. Mix 8:2 and Mix 6:4 silages showed high quality, based on the low pH, acetic acid, and ammonia nitrogen levels and the high lactic acid, crude protein, and crude fat contents. The bacterial diversity was affected by the mixing ratio of the two forage species. The genus Lactobacillus dominated the bacterial community in Mix 10:0 silage, whereas with the addition of hairy vetch, the relative abundance of unclassified-Enterobacter increased from 7.67% to 41.84%, and the abundance of Lactobacillus decreased from 50.66% to 13.76%.

CONCLUSION

The silage quality of whole-plant corn can be improved with inclusion levels of hairy vetch from 20% to 40%.

Effects of Vachellia mearnsii Tannin Extract as an Additive on Fermentation Quality, Aerobic Stability, and Microbial Modulation of Maize Silage

Maize silage is produced to alleviate the effects of forage shortages on ruminant animals, particularly during the dry season. Microorganisms play a significant role in silage fermentation and thus, to a large extent, determine the silage quality. The modulation of silage microorganisms may help to inhibit undesirable bacteria and improve the silage quality. Therefore, condensed tannin extract from Vachellia mearnsii bark was used as an additive in maize silage during ensiling. Hence, this study evaluated the effects of a tannin extract (condensed tannin) additive on the fermentative quality, aerobic stability, and bacterial composition of maize silage. A mini-silo experiment on maize with five treatments was conducted for 75 days. The silage treatments were as follows: (T1) maize forage with no inoculation (negative control); (T2) maize forage inoculated with LAB and 1% tannin extract; (T3) maize forage inoculated with LAB only (positive control); (T4) and maize forage inoculated with LAB and 2% tannin extract; (T5) maize forage inoculated with LAB and 3% tannin extract. The results showed that the additives modulated the silage microorganism composition. However, this was without affecting the silage's fermentative quality and aerobic stability. All the silages recorded a pH below 4.2, which indicated well-fermented silage. The tannin extract suppressed the growth of undesirable bacteria, such as Dysgonomonas, Gluconacetobacter and Clostridium genera, while promoting desirable bacteria, such as Lactobacillus and Weissella genera, which were attributed to the silage quality. It is thus concluded that tannins can be strategically used as silage additives to modulate the microbial composition of silage and improve the silage quality by promoting the dominance of the desirable bacteria in the silage.

Alfalfa as a vegetable source of β-carotene: The change mechanism of β-carotene during fermentation

The objectives of this study were to explore the β-carotene-producing bacteria and ascertain the main factors affecting β-carotene content via investigating the effects of various additives on β-carotene content, bacterial community succession, and quality of fermented alfalfa, using single-molecule real-time (SMRT) sequencing technology. Fresh alfalfa was fermented without (CON) or with squalene (SQ), the combination of Lactobacillus plantarum and cellulase (LPEN), and the combination of SQ and LPEN (SQLPEN) for 3, 45, and 90 d. The results showed that relative to the fresh alfalfa, extensive β-carotene loss in all groups occurred in the early fermentation phase (3 d) since epiphytic Pantoea agglomerans with the ability to produce β-carotene disappeared and β-carotene was oxidized by lipoxygenase and peroxidase. With the prolonged fermentation days, β-carotene content in all groups increased due to bacterial community succession in the middle and late phases of fermentation (45 and 90 d). The species L. parabuchneri, L. kunkeei, and L. kullabergensis (r = 0.591, 0.366, 0.341, orderly) had positive correlations with β-carotene content (P < 0.05). Bacterial functional potential prediction showed that species L. kunkeei, L. helsingborgensis, and L. kullabergensis had positive (r = 0.478, 0.765, 0.601) correlations with C10-C20 isoprenoid biosynthesis (P < 0.01), and L. helsingborgensis and L. kullabergensis had positive (r = 0.805, 0.522) correlations with β-carotene biosynthesis (P < 0.01). Additionally, the pH and propionic acid (r = -0.567, -0.504) had negative correlations with β-carotene content (P < 0.01). The CON group was preserved well after 90 d, LPEN and SQLPEN further improved fermentation quality. In conclusion, certain Lactobacillus had the potential for β-carotene biosynthesis, and high pH and propionic acid content were the unbenefited factors for β-carotene retention in fermented alfalfa.

Dynamics associated with fermentation and aerobic deterioration of high-moisture Italian ryegrass silage made using Lactobacillus plantarum and caproic acid

AIMS

To determine the fermentation quality, aerobic stability, and chemical composition of Italian ryegrass silage prepared with Lactobacillus plantarum (LP), caproic acid (CA), and their combination during ensiling and feed-out phase.

METHODS AND RESULTS

Six treatments: control (CON), LP, 0.15% caproic acid (LCA), 0.2% caproic acid (HCA), LCA + LP, and HCA + LP were employed for 30 days ensiling and an 8-days aerobic stability test. LP had similar pH value and lactic acid content with LCA + LP, while the contents of NH3-N and total VFAs in LCA + LP were significantly lower than those in LP and CON, and the fermentation quality of LCA + LP performed best among all silages. As air-exposure extended, contents of water-soluble carbohydrates (WSC), lactic, and acetic acids decreased, while pH, and NH3-N content increased significantly. The population of lactic acid bacteria gradually decreased in contrast to increased counts of aerobic bacteria and yeasts. Compared with LCA, 0.2% CA delayed the aerobic deterioration as judged by a slower increase in pH and high residual of WSC and lactic acid, and negligible ethanol content and anaerobe spores counts remained in HCA at the end of air exposure. Compared with CON (73 h), LP showed less aerobic stability (38 h), whereas HCA and HCA + LP prolonged aerobic stability for 210 and 152 h, better than LCA (109 h) and LCA + LP (146 h).

CONCLUSIONS

Lactobacillus plantarum apparently improved the fermentation quality, and combined with CA exhibited greater efficiency in inhibiting undesirable microorganism during ensiling. CA at 0.2% optimally extended the aerobic stability.

Cellulase-lactic acid bacteria synergy action regulates silage fermentation of woody plant

BACKGROUND

Feed shortage is an important factor limiting livestock production in the world. To effectively utilize natural woody plant resources, we used wilting and microbial additives to prepare an anaerobic fermentation feed of mulberry, and used PacBio single-molecule real-time (SMRT) sequencing technology to analyse the "enzyme-bacteria synergy" and fermentation mechanism.

RESULTS

The fresh branches and leaves of mulberry have high levels of moisture and nutrients, and also contain a diverse range of epiphytic microorganisms. After ensiling, the microbial diversity decreased markedly, and the dominant bacteria rapidly shifted from Gram-negative Proteobacteria to Gram-positive Firmicutes. Lactic acid bacteria (LAB) emerged as the dominant microbial population, resulting in increased in the proportion of the carbohydrate metabolism and decreased in the proportion of the amino acid and "global and overview map" (GOM) metabolism categories. The combination of cellulase and LAB exhibited a synergistic effect, through which cellulases such as glycanase, pectinase, and carboxymethyl cellulase decomposed cellulose and hemicellulose into sugars. LAB converted these sugars into lactic acid through the glycolytic pathway, thereby improving the microbial community structure, metabolism and fermentation quality of mulberry silage. The GOM, carbohydrate metabolism, and amino acid metabolism were the main microbial metabolic categories during ensiling. The presence of LAB had an important effect on the microbial community and metabolic pathways during silage fermentation. A "co-occurrence microbial network" formed with LAB, effectively inhibiting the growth of harmful microorganisms, and dominating the anaerobic fermentation process.

CONCLUSIONS

In summary, PacBio SMRT was used to accurately analyse the microbial network information and regulatory mechanism of anaerobic fermentation, which provided a scientific basis for the study of woody silage fermentation theory. This study reveals for the first time the main principle of the enzyme-bacteria synergy in a woody silage fermentation system, which provides technical support for the development and utilization of woody feed resources, and achieves sustainable livestock production.

Effect of isolated lactic acid bacteria on the quality and bacterial diversity of native grass silage

Objective

The objective of this study was to isolate lactic acid bacteria (LAB) from native grasses and naturally fermented silages, determine their identity, and assess their effects on silage quality and bacterial communities of the native grasses of three steppe types fermented for 60 days.

Methods

Among the 58 isolated LAB strains, Limosilactobacillus fermentum (BL1) and Latilactobacillus graminis (BL5) were identified using 16S rRNA sequences. Both strains showed normal growth at 15- 45°C temperature, 3-6.5% NaCl concentration, and pH 4-9. Two isolated LAB strains (labeled L1 and L5) and two commercial additives (Lactiplantibacillus plantarum and Lentilactobacillus buchneri; designated as LP and LB, respectively) were added individually to native grasses of three steppe types (meadow steppe, MS; typical steppe, TS; desert steppe, DS), and measured after 60 d of fermentation. The fresh material (FM) of different steppe types was treated with LAB (1 × 10⁵ colony forming units/g fresh weight) or distilled water (control treatment [CK]).

Results

Compared with CK, the LAB treatment showed favorable effects on all three steppe types, i.e., reduced pH and increased water-soluble carbohydrate content, by modulating the microbiota. The lowest pH was found in the L5 treatment of three steppe types, at the same time, the markedly (p < 0.05) elevated acetic acid (AA) concentration was detected in the L1 and LB treatment. The composition of bacterial community in native grass silage shifted from Pantoea agglomerans and Rosenbergiella nectarea to Lentilactobacillus buchneri at the species level. The abundance of Lentilactobacillus buchneri and Lactiplantibacillus plantarum increased significantly in L1, L5, LP, and LB treatments, respectively, compared with CK (p < 0.05).

Conclusion

In summary, the addition of LAB led to the shifted of microbiota and modified the quality of silage, and L. fermentum and L. graminis improved the performance of native grass silage.

The metabolome and bacterial composition of high-moisture Italian ryegrass silage inoculated with lactic acid bacteria during ensiling

BACKGROUND

With its high nutritional value and productivity, Italian ryegrass as a biomass feedstock constantly supplies rumen degradable nitrogen and digestible fiber to ruminants. However, biofuel production is easily reduced during ensiling due to the high-moisture content of Italian ryegrass, leading to economic losses. Lactic acid bacteria inoculants could improve lignocellulosic degradation and fermentation quality and decrease dry matter loss during the bioprocessing of silage. Therefore, this study analyzed the effects of Lactobacillus buchneri TSy1-3 (HE), Lactobacillus rhamnosus BDy3-10 (HO), and the combination of HE and HO (M) on fermentation quality, bacterial community and metabolome in high-moisture Italian ryegrass silage during ensiling.

RESULTS

The results showed that the pH value was significantly lower in the HO groups than in the other treatments at the end of ensiling, and the dry matter and acetic acid contents were significantly higher in the HO group than in the other inoculated groups. All inoculants decreased the diversity of the bacterial community and significantly increased the relative abundance of Lactobacillus. Inoculation with HO significantly improved the concentrations of organic acids, dipeptides, ferulic acid, apigenin, and laricitrin. Compared with Lactobacillus buchneri TSy1-3 (HE), HO significantly upregulated the flavonoid compounds in the flavone and flavonol biosynthesis pathway.

CONCLUSIONS

Overall, these findings suggest that inoculation with HO was beneficial for the development of Italian ryegrass as a biomass feedstock, improving fermentation quality, accelerating changes in bacterial community composition and increasing biofunctional metabolites in high-moisture Italian ryegrass silage.

Assessing the impact of phyllosphere microbiota on dynamics of in-silo fermentation of Italian ryegrass harvested at heading and blooming stages

BACKGROUND

The present study aimed to investigate the relationship between the phyllosphere microbiota of Italian ryegrass (Lolium multiflorum Lam.) harvested at heading (H) [> 50% earing rate or 216 g kg^-1 fresh weight (FW)] and blooming (B) (> 50% bloom or 254 g kg^-1 FW) stages and in-silo fermentation products, and the composition, abundance, diversity and activity of bacterial community. In total, 72 (4 treatments × 6 ensiling durations × 3 replicates) laboratory scale (400 g) silages of Italian ryegrass were prepared: (i) irradiated heading stage silages (IRH) (n = 36) were inoculated with phyllosphere microbiota inoculum (2 mL) eluted from fresh Italian ryegrass at either heading (IH) (n = 18) or blooming (IB) (n = 18) stages; (ii) irradiated blooming stage silages (IRB) (n = 36) were inoculated with either IH (n = 18) or IB (n = 18). Triplicate silos of each treatment were analyzed after 1, 3, 7, 15, 30 and 60 days of ensiling.

RESULTS

In fresh forage, Enterobacter, Exiguobacterium and Pantoea were the three major genera at heading stage, and Rhizobium, Weissella and Lactococcus were the most abundant genera at blooming stage. Higher metabolic activity was found in IB. After 3 days of ensiling, the large amounts of lactic acid in IRH-IB and IRB-IB can be attributed to the higher abundances of Pediococcus and Lactobacillus, 1-phosphofructokinase, fructokinase, l-lactate dehydrogenase and glycolysis I, II and III.

CONCLUSION

The composition, abundance, diversity and functionality of the phyllosphere microbiota of Italian ryegrass at different growth stages could remarkably affect silage fermentation characteristics. © 2023 Society of Chemical Industry.

The Effect of Lactiplantibacillus plantarum ZZU203, Cellulase-Producing Bacillus methylotrophicus, and Their Combinations on Alfalfa Silage Quality and Bacterial Community

This study assessed the effects of Lactiplantibacillus plantarum (ZZU203), cellulase-producing Bacillus methylotrophicus (CB), or their combination (ZZU203_CB) on the fermentation parameters of alfalfa after 10 and 60 days of ensiling. Additionally, the bacterial community compositions were analyzed using absolute quantification 16S-seq (AQS). The results showed that CB silage displayed a higher lactic acid (LA) concentration at 10 d, a higher abundance of Lactobacillus, and lower abundance of Pediococcus, Enterococcus, and Weissella than those in the control (CK) silage. Compared with CK silage, the ZZU203 silage increased LA concentration, fructose and rhamnose concentrations, and the abundance of Lactobacillus, and decreased pH value, ammoniacal nitrogen, acetic acid, neutral detergent fiber and acid detergent fiber concentrations, and the abundance of Pediococcus, Enterococcus, Weissella, Hafnia, and Garciella after 60 days of ensiling. In addition, ZZU203 and ZZU203_CB silage had a similar silage quality and bacterial community, while the inoculation of ZZU203_CB significantly promoted LA accumulation and the numbers of Lactobacillus at 10 d compared with ZZU203 silage. Therefore, ZZU203 or a combination of ZZU203 and CB can be used as potential silage additives to improve the silage quality of alfalfa.

Effects of Bacillus coagulans and Lactobacillus plantarum on the Fermentation Characteristics, Microbial Community, and Functional Shifts during Alfalfa Silage Fermentation

This study aimed to investigate the potential of Bacillus coagulans (BC) as an inoculant in alfalfa silage fermentation. Fresh alfalfa was harvested at a dry matter (DM) content of 329.60 g/kg fresh weight (FW), and inoculated without (CON) or with BC (1 × 106 CFU/g FW), Lactobacillus plantarum (LP, 1 × 106 CFU/g FW), and their combinations (LP+BC, 1 × 106 CFU/g FW, respectively). Samples were taken at 3, 7, 14, 30, and 60 d, with three replicates for each. The prolonged ensiling period resulted in a decrease in pH values and an increase in lactic acid (LA) concentrations in alfalfa silages. After 60 d of fermentation, the application of BC and LP decreased the pH values and increased LA concentrations in treated silages, especially when their combination was applied. Application of BC preserved more water-soluble carbohydrates (WSC), and further application of BC increased WSC in LP+BC-treated silage compared to LP-treated silage. There was no significant difference in the crude protein (CP) content between the CON and treated silages, however, the BC and LP treatments reduced the ammonia nitrogen (NH3-N) concentration, especially when their combination was applied. Additionally, the BC and LP-treated silages had lower neutral detergent fiber (NDF) and acid detergent fiber (ADF) when compared to the CON silage (p < 0.001). Inoculants also increased Lactobacillus abundance and decreased Enterococcus abundance after 60 d of fermentation. Spearman's rank correlation analysis revealed a positive correlation between LA concentration and Lactobacillus abundance. It was noteworthy that LP, BC, and their combination increased the relative abundances of carbohydrate metabolism, energy metabolism, cofactors, and vitamin metabolism, decreasing the relative abundances of amino acid metabolism and drug resistance: antimicrobial. Therefore, the inclusion of BC increased the fermentation quality of alfalfa silage, with the optimal combination being LP+BC. According to the findings, BC could be considered a viable bioresource for improving fermentation quality.

Effects of Different Types of LAB on Dynamic Fermentation Quality and Microbial Community of Native Grass Silage during Anaerobic Fermentation and Aerobic Exposure

Silage of native grasses can alleviate seasonal forage supply imbalance in pastures and provide additional sources to meet forage demand. The study aimed to investigate the effects of Lactobacillus plantarum (LP), Lactobacillus buchneri (LB), and Lactobacillus plantarum in combination with Lactobacillus buchneri (PB) on the nutritional quality, fermentation quality, and microbial community of native grass silage at 2, 7, 15, and 60 days after ensiling and at 4 and 8 days after aerobic exposure. The results showed that dry matter content, crude protein content, the number of lactic acid bacteria, and lactic acid and acetic acid content increased and pH and ammonia nitrogen content decreased after lactic acid bacteria (LAB) inoculation compared with the control group (CK). LP had the lowest pH and highest lactic acid content but did not have greater aerobic stability. LB maintained a lower pH level and acetic acid remained at a higher level after aerobic exposure; aerobic bacteria, coliform bacteria, yeast, and molds all decreased in number, which effectively improved aerobic stability. The effect of the compound addition of LAB was in between the two other treatments, having higher crude protein content, lactic acid and acetic acid content, lower pH, and ammonia nitrogen content. At the phylum level, the dominant phylum changed from Proteobacteria to Firmicutes after ensiling, and at the genus level, Lactiplantibacillus and Lentilactobacillus were the dominant genera in both LAB added groups, while Limosilactobacillus was the dominant genus in the CK treatment. In conclusion, the addition of LAB can improve native grass silage quality by changing bacterial community structure. LP is beneficial to improve the fermentation quality in the ensiling stage, LB is beneficial to inhibit silage deterioration in the aerobic exposure stage, and compound LAB addition is more beneficial to be applied in native grass silage.

Diurnal Variation of Epiphytic Microbiota: an Unignorable Factor Affecting the Anaerobic Fermentation Characteristics of Sorghum-Sudangrass Hybrid Silage

Forage epiphytic microbiota exhibits pronounced changes in composition and function throughout the day. However, the effects of these changes on silage fermentation are rarely explored. Here, we transplanted the epiphytic microbiota of sorghum-sudangrass hybrid (SSG) harvested at 7:00 h (AM), 12:00 h (M), and 17:00 h (PM) to sterilized SSG to evaluate the effects of diurnal variation of epiphytic microbiota on fermentation characteristics. During fermentation, remarkable differences in bacterial community successions were observed between silages inoculated with AM and M microbiota. Compared to AM microbiota, M microbiota inoculation increased the proportions of Pantoea dispersa, Leuconostoc lactis, Enterobacter, and Klebsiella variicola, whereas it decreased the proportions of Weissella cibaria and Lactobacillus plantarum during fermentation. This led to the most rapid pH declines and organic acid production in AM silage and the slowest in M silage. Both M and PM microbiota affected the bacterial cooccurrence patterns, indicated by decreased complexity and stability in the community structures of M and PM silages compared to that of AM silage. The predicted functions indicated that some key carbohydrate metabolism pathways related to lactic acid synthesis were downregulated, while some competing pathways (ascorbate and aldarate metabolism and C5-branched dibasic acid metabolism) were upregulated in M silage compared to AM silage after 3 days of fermentation. Correlation analysis revealed positive correlations between competing pathways and enterobacterial species. The current study highlights the importance of diurnal variation of epiphytic microbiota in affecting the silage bacterial community, potentially providing an effective strategy to improve silage quality by optimizing harvest time. IMPORTANCE Ensiling is a way to preserve wet biomass for animal and bioenergy production worldwide. The fermentation quality of silage is largely dependent on the epiphytic microbiota of the material. Plant epiphytic microbiota exhibit diurnal changes in composition and function. However, the effects of these changes on silage fermentation are rarely explored. The results presented here demonstrated that diurnal variation of epiphytic microbiota could affect the fermentation characteristics and bacterial community during SSG fermentation. Marked bacterial community differences were observed between AM and M silages during the initial 3 days of fermentation. The dominance rate of Lactobacillus plantarum was highest in AM silage, whereas enterobacterial species were more abundant in M silage. The predicted function revealed downregulated lactic acid synthesis pathways and upregulated competing pathways in M silage compared to those in AM silage. This study provides clues for technological-parameter optimization of the fermentation process by the selection of harvest time.

Potential for volatile fatty acid production via anaerobically-fermenting rice straw pretreated with silage effluent and phenyllactic acid

To resolve environmental problems associated with rice straw and silage effluent disposal, silage effluent pretreating rice straw for the anaerobic production of volatile fatty acids (VFAs) was investigated. To prevent the lactic acid bacteria in silage effluent from inhibiting anaerobic fermentation, four phenyllactic acid (PLA) levels were set (0, 0.1, 0.3, 0.5 mg/kg). The total VFA yields of treatments pretreated only with silage effluent (CK) were higher than the groups combined with PLA during 15 days fermentation. Compared to PLA treatments, the total VFA of CK increased by 11.4 % ∼ 25.1 % on day 15. The CK showed higher lactic and propionic acid contents and lower pH values (<4.9). The PLA treatments decreased Lactobacillus abundance while increasing bacterial richness and evenness, and acetic and butyric acid contents. These demonstrated silage effluent has the potential to be used as a biological pretreatment for VFA production in anaerobic fermentation.

Ensiling pretreatment fortified with laccase and microbial inoculants enhances biomass preservation and bioethanol production of alfalfa stems

This study investigated the potential of ensiling pretreatment fortified with laccase and a lactic acid bacteria (LAB) inoculant on improving the utilization of alfalfa stems for bioethanol production. The alfalfa stems were ensiled with no additives (Con), 0.04 % laccase (LA), a LAB inoculant containing Pediococcus pentosaceus at 1 × 10⁶ fresh weight (FW) and Pediococcus acidilactici at 3 × 10⁵ cfu/g FW (PP), and a combination of LA and PP (LAP) for 120 days. By reshaping the bacterial community structure of alfalfa stem silages toward a higher abundance of Lactobacillus, the addition of laccase and LAB inoculant either alone or in combination facilitated lactic acid fermentation to reduce fermentation losses, as evidenced by low concentrations of ammonia nitrogen (53.7 to 68.9 g/kg total nitrogen) and ethanol (2.63 to 3.55 g/kg dry matter). All additive treatments increased lignocellulose degradation and soluble sugars concentrations of alfalfa stem silages. Due to delignification and polyphenol removal, glucan and xylan conversion (70.3 % vs. 35.7 % and 51.6 % vs. 27.9 %, respectively) and ethanol conversion efficiency (53.9 % vs. 26.4 %) of alfalfa stems were greatly increased by ensiling fortified with LA versus Con, and these variables (79.8 % for glucan, 58.7 % for xylan, and 60.1 % for ethanol conversion efficiency) were further enhanced with a synergistic effect of LA and PP fortification. The spearman correlation analysis revealed that bioethanol fermentation of silage biomass was closely related to ensiling parameters and total phenols. In conclusion, ensiling pretreatment with LA and PP combination offered a feasible way to efficient utilization of alfalfa stems for bioethanol production.

Response of fermentation quality and microbial community of oat silage to homofermentative lactic acid bacteria inoculation

Oat (Avena sativa L.) is one of the important forage crops in the world. However, oat grown in Southwest China has higher moisture content and their preservation face significant challenges. In addition, existing commercial lactic acid bacteria (LAB) have poor fermentation effects in hot and humid regions. Consequently, the current study investigated the response of oat fermentation quality and microbial community to self-selected LAB inoculation. The treatments were: CK, sterilized water; LP694, Lactobacillus plantarum 694; LR753, Lactobacillus rhamnosus 753; and LPLR, LP694 combined with LR753, followed by 1, 3, 7, 14, and 60 days (d) of fermentation. The results showed that LAB inoculation significantly raised the lactic acid content, and decreased the level of pH value, acetic acid, and ammonia-N in oat silage. The LR753 group had a significantly higher (p < 0.05) lactic acid content (60.95 g kg-1 DM), and lower pH value (3.95) and ammonia-N content (10.1 g kg-1 DM) followed by the LPLR group. The LR753 showed lower NDF (54.60% DM) and ADF (39.73% DM) contents than other groups. The Lactobacillus was a prevalent genus in LAB-treated groups, and its relative abundance reached maximum in LP694 (69%) on day 3, while in the LR753 group (72%) on 60 days. The Lactobacillus rhamnosus, Lactobacillus plantarum, and Lactobacillus fermentum became the dominant species in LAB-treated groups with fermentation time. The Lactobacillus genus was positively correlated with WSC (R = 0.6, p < 0.05), while negatively correlated with pH (R = -0.5, p < 0.05), and BA (R = -0.5, p < 0.01). Overall, the LR753 group had better fermentation quality and preservation of nutritional components providing theoretical support and guidance for future oat silage production in Southwest China.

Effect of storage time on the silage quality and microbial community of mixed maize and faba bean in the Qinghai-Tibet Plateau

Tibetan Plateau is facing serious shortage of forage in winter and spring season due to its special geographical location. Utilization of forages is useful to alleviate the forage shortage in winter and spring season. Consequently, the current study was aimed to evaluate the influence of storage time on the silage quality and microbial community of the maize (Zea mays L.) and faba bean (Vicia faba L.) mixed silage at Qinghai-Tibet Plateau. Maize and faba bean were ensiled with a fresh weight ratio of 7:3, followed by 30, 60, 90, and 120 days of ensiling. The results showed the pH value of mixed silage was below 4.2 at all fermentation days. The LA (lactic acid) content slightly fluctuated with the extension of fermentation time, with 33.76 g/kg DM at 90 days of ensiling. The AA (acetic acid) and NH₃-N/TN (ammonium nitrogen/total nitrogen) contents increased with the extension of fermentation time and no significantly different between 90 and 120 days. The CP (crude protein) and WSC (water soluble carbohydrate) contents of mixed silage decreased significantly (P < 0.05) with ensiling time, but the WSC content remained stable at 90 days. The Proteobacteria was the predominant phyla in fresh maize and faba bean, and Pseudomonas and Sphingomonas were the predominant genera. After ensiling, Lactobacillus was the prevalent genus at all ensiling days. The relative abundance of Lactococcus increased rapidly at 90 days of ensiling until 120 days of fermentation. Overall, the storage time significant influenced the silage fermentation quality, nutrient content, and microbial environment, and it remained stable for 90 days of ensiling at Qinghai-Tibet Plateau. Therefore, the recommended storage time of forage is 90 days in Qinghai-Tibet Plateau and other cool areas.

Effect of different regions on fermentation profiles, microbial communities, and their metabolomic pathways and properties in Italian ryegrass silage

Introduction

Italian ryegrass is less studied in northern China due to high-quality forage grass has not been fully utilized. Full utilization of high-quality forage grass helps to alleviate the shortage of forage grass in winter and spring season and guarantee stable development of livestock production. Consequently, this study was aimed to evaluate the effects of different regions in northern China on the fermentative products, bacterial community compositions, and metabolic pathways and metabolites of Italian ryegrass silage.

Methods

The Italian ryegrass was harvested from three regions (Ordos-WK; Hohhot-AK; Ulanqab-SYK) and ensiled for 60 days. Single molecule real-time (SMRT) sequencing and ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS/MS) were used to analyze bacterial communities and metabolites, respectively.

Results

After 60 d of fermentation, the SYK group had the lowest pH (4.67), the highest lactic acid contents (95.02 g/kg DM) and largest lactic acid bacteria populations (6.66 log₁₀ cfu/g FM) among the treatment groups. In addition, the SYK group had the highest abundance of Lactiplantibacillus plantarum (63.98%). In SYK group, isoquinoline alkaloid biosynthesis was the significantly enriched (p < 0.05) and high-impact value (0.0225) metabolic pathway. In AK group, tryptophan metabolism the was the significantly enriched (p < 0.001) and high-impact value (0.1387) metabolic pathway. In WK group, citrate cycle (TCA cycle) was the significantly enriched (p < 0.001) and high-impact value (0.1174) metabolic pathway. Further, Lactiplantibacillus plantarum was positively correlated with cinnamic acid, tetranor 12-HETE, D-Mannitol, (2S)-2-amino-4-methylpentanoic acid L-Leucine, guanine, isoleucyl-aspartate and 3,4-Dihydroxyphenyl propanoate, but negatively correlated with isocitrate and D-mannose.

Discussion

In conclusion, this study can improve our understanding of the ensiling microbiology and metabolomics in different regions to further regulate the fermentation products and promote livestock production.

Effects of growth stage on the fermentation quality, microbial community, and metabolomic properties of Italian ryegrass (Lolium multiflorum Lam.) silage

Introduction

This study aimed to investigate the effects of different growth stages (booting period-SYK; initial flowering-SCK; full flowering-SSK) on the fermentation quality, microbial community, metabolic pathways and metabolomic characteristics of Italian ryegrass silage.

Methods

Single molecule real-time (SMRT) sequencing and ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS/MS) were used to analyze bacterial communities and metabolites, respectively.

Results

After 60 d of fermentation, SYK had the lowest pH and the highest lactic acid content, which were significantly different from the other groups. The bacteria with the highest abundance in SYK, SCK and SSK groups were Lactiplantibacillus plantarum (63.98%), Weissella minor (28.82%) and Levilactobacillus brevis (64.81%), respectively. In addition, among the main differential metabolites in different growth stages, the number of amino acids was the most, and the corresponding metabolic pathways were mainly amino acid metabolic pathways. The biosynthesis of phenylalanine, tyrosine and tryptophan was significantly enriched (p<0.01) at booting stage and full flowering stage. Purine metabolism and ABC transporter pathway were significantly enriched at the initial flowering (p<0.001). Lactiplantibacillus plantarum had a negative correlation with xanthine and ganoderic acid F. Weissella minor had a positive correlation with D-Mannose and ganoderic acid F. Levilactobacillus brevis had a positive correlation with xanthine, and Latilactobacillus sakei had a positive correlation with cinnamic acid, D-Mannose, 2-Hydroxycinnamic acid and uridine.

Discussion

In conclusion, this study reveals the interaction mechanisms between ryegrass raw materials at different growth stages and epiphytic microorganisms during ensiling fermentation, providing new ideas for screening functional lactic acid bacteria, and laying a theoretical foundation for the production of safe and high-quality silage.

Characteristics of lactic acid bacteria, microbial community and fermentation dynamics of native grass silage prepared in Inner Mongolian Plateau

Introduction

To prepare high-quality silage, we studied the chemical composition, silage fermentation, characterization, and identification of lactic acid bacteria (LAB) associated with the silage fermentation of native grass on the Inner Mongolian Plateau.

Methods

LAB were isolated from fresh native grass and their silage, and silages were prepared using a small-scale fermentation system with 2-3 cm length in plastic bags.

Results

The dominant species of native grasses used were Stipa baicalensis, Leymus chinensis, Cleistogenes squarrosa, Melissilus ruthenicus and Pulsatilla turczaninovii, which contained 47.83-59.43 % moisture, 55.12-67.74 % neutral detergent fiber (NDF), and 8.72-14.55 crude protein (CP), and these nutrients did not change greatly during ensiling. Good preservation with a relatively low pH (below 4.44) and high (p < 0.05) lactic acid content (>0.58) was obtained after ensiling. Based on the morphological and biochemical characteristics, these isolates were divided into 12 groups (A-L). All isolate strains were gram-positive and catalase-negative bacteria that produce lactic acid from glucose. Group A-K were cocci, while group L was rod-shaped. Group A-E formed D-lactic acid, but group H-K formed L-lactic acid, and other groups formed DL-lactic acid. Group A-E were heterofermentative, and Group F-L were homofermentative types of LAB. According to the 16S rRNA gene sequences analysis, strains were identified as genus Leuconostoc (A, B, and C), Weissellla (D, E), Pediococcus (F, G), Enterococcus (H, I, J and K), and Lactiplantibacillus (L). Enterococcus (E.) faecium (29.17%, percentage of total isolates) and Pediococcus (P.) acidilactici (18.75%) were the most frequently occurring dominant species.

Discussion

This study suggests that the native grasses contained abundant LAB species, and they can be used as good-quality silages in animal husbandry. In addition, the strains P. acidilactici and E. faecium were the most frequently isolated from native grass silages as dominant species which can be a potentially excellent inoculant for native grass silage.

Near-infrared spectroscopy for rapid evaluation of winter cereals and Italian ryegrass forage mixtures

Near-infrared (NIR) spectroscopy was employed to determine the differences between forage mixtures of winter cereals and Italian ryegrass and to evaluate fermentation characteristics of mixed silages. Forages were harvested on five phases (Cuts 1-5), with 1 week interval (n = 100). The yield of the last harvest (Cut 5) was ensiled and analyzed on four different days (D0, D7, D14, and D90) (n = 80). Principal component analysis based on the NIR data revealed differences according to the days of harvest, differences between winter cereals and Italian ryegrass forages, and differences in the fermentation stages of silages. The partial least square regression models for crude protein (CP), crude fiber (CF), and ash gave excellent determination coefficient in cross-validation (R² _CV  > 0.9), while models for ether extract (EE) and total sugar content were weaker (R² _CV  = 0.87 and 0.74, respectively). The values of root mean square error of cross-validation were 0.59, 0.76, 0.22, 0.31, and 2.36 %DM, for CP, CF, EE, ash, and total sugar, respectively. NIR proved to be an efficient tool in evaluating type and growth differences of the winter cereals and Italian ryegrass forage mixtures and the quality changes that occur during ensiling.

Perilla frutescens as potential antimicrobial modifier to against forage oat silage spoilage

The aim of this study was to investigate the influence of Perilla frutescens, alone or in combination with Lactobacillus plantarum a214 or citric acid, on forage oat silage quality, bacterial and fungal microbiological profile during ensiling and aerobic exposure. With the exception of Perilla frutescens, all additives could improve silage quality of forage oat based on lower ammonia-nitrogen content and higher residual of water soluble carbohydrates during anaerobic fermentation compared to control silage, especially in Perilla frutescens combined with citric acid (CAPF). Lactobacillus was the dominant bacteria in all silages, while CAPF group increased the relative abundance of Lactobacillus lindneri and Lactobacillus brevis compared to control silage. The application of Perilla frutescens suppressed the relative abundance of yeasts such as Pichia fermentans and Wickerhamomyces anomalus in response to aerobic exposure, especially in CAPF treatment, leading to high acetic acids and lower dry matter loss, as well as good aerobic stability. Therefore, Perilla frutescens, alone or in combination with citric acid, has potential to improve aerobic stability of forage oat silage by shifting bacterial and fungal community composition, and can be used as new additive to prepare high-quality silage for animal production.

Effect of Formic Acid and Inoculants on Microbial Community and Fermentation Profile of Wilted or Un-Wilted Italian Ryegrass Silages during Ensiling and Aerobic Exposure

Wilted (around 35% DM) or un-wilted (around 35% DM) Italian ryegrass treated with three additives (formic acid, FA; Lactobacillus plantarum, LP; Lactobacillus buchneri, LB) was utilized to evaluate the effects of the dry matter (DM) contents on the microbial community and fermentation characteristics, which was ensiled for 60 days in a laboratory-scale silo, followed by 3 days of aerobic exposure. Significantly lower pH and higher lactic acid (LA) contents were observed in the LP-treated group ensiled at both DM contents (differences were significant when p < 0.05). The contents of LA, acetic acid (AA), numbers of lactic acid bacteria (LAB) and ammonia nitrogen (NH3-N) in the FA-treated group were significantly lower than those in other treatments (p < 0.05). L. buchneri was the dominant bacteria after 60 days fermentation, while Enterobacteria became prevalent after 3 days of aerobic exposure. L. buchneri was found in the LB-treated group with higher acetic acid. Although the best fermentation quality was observed in the LP-treated silages, the aerobic stability was lowest compared to other groups (p < 0.05). In conclusion, our findings suggest that the DM content of Italian ryegrass affected its epiphytic microbial community and the effectiveness of the different type of additives. Formic acid was more suitable for un-wilted Italian ryegrass silage, L. plantarum had a better effect in wilted Italian ryegrass silage, and L. buchneri prolonged the aerobic stability of Italian ryegrass. DM content and purpose of ensiling should be the key factors for choosing different types of additives for Italian ryegrass silage.

Current approaches on the roles of lactic acid bacteria in crop silage

Lactic acid bacteria (LAB) play pivotal roles in the preservation and fermentation of forage crops in spontaneous or inoculated silages. Highlights of silage LAB over the past decades include the discovery of the roles of LAB in silage bacterial communities and metabolism and the exploration of functional properties. The present article reviews published literature on the effects of LAB on the succession, structure, and functions of silage microbial communities involved in fermentation. Furthermore, the utility of functional LAB in silage preparation including feruloyl esterase-producing LAB, antimicrobial LAB, lactic acid bacteria with high antioxidant potential, pesticide-degrading LAB, lactic acid bacteria producing 1,2-propanediol, and low-temperature-tolerant LAB have been described. Compared with conventional LAB, functional LAB produce different effects; specifically, they positively affect animal performance, health, and product quality, among others. In addition, the metabolic profiles of ensiled forages show that plentiful probiotic metabolites with but not limited to antimicrobial, antioxidant, aromatic, and anti-inflammatory properties are observed in silage. Collectively, the current knowledge on the roles of LAB in crop silage indicates there are great opportunities to develop silage not only as a fermented feed but also as a vehicle of delivery of probiotic substances for animal health and welfare in the future.

Fermentation Characteristics, Microbial Compositions, and Predicted Functional Profiles of Forage Oat Ensiled with Lactiplantibacillus plantarum or Lentilactobacillus buchneri

This study aimed to investigate the effects of lactic acid bacteria (LAB) inoculants on the fermentation quality, microbial compositions, and predicted functional profiles of forage oat. The forage oat was inoculated with distilled water, Lentilactobacillus buchneri (LB), and Lactiplantibacillus plantarum (LP) as the control (CON), LB and LP treatments, respectively, and the addition of Lentilactobacillus buchneri (LB) or Lactiplantibacillus plantarum (LP) resulted in 1 × 106 colony-forming units/g of fresh weight. After 30 days of fermentation, the lowest pH (4.23) and the lowest content of ammoniacal nitrogen (NH3-N) in dry matter (DM, 4.39%) were observed in the LP treatment. Interestingly, there was a significant (p < 0.05) difference in lactic acid (LA) concentration among the three treatments. The LP treatment had the highest lactate concentration (7.49% DM). At the same time, a markedly (p < 0.05) elevated acetic acid (AA) concentration (2.48% DM) was detected in the LB treatment. The Shannon and Chao1 indexes of bacterial and fungal communities in all the silage samples decreased compared to those in the fresh materials (FM). Proteobacteria was the dominant phylum in the FM group and shifted from Proteobacteria to Firmicutes after ensiling. Lactobacillus (64.87%) and Weissella (18.93%) were the predominant genera in the CON, whereas Lactobacillus dominated the fermentation process in the LB (94.65%) and LP (99.60%) treatments. For the fungal community structure, the major genus was Apiotrichum (21.65% and 60.66%) in the FM and CON groups after 30 days of fermentation. Apiotrichum was the most predominant in the LB and LP treatments, accounting for 52.54% and 34.47%, respectively. The genera Lactococcus, Pediococcus, and Weissella were negatively associated with the LA content. The genus Ustilago and Bulleromyces were positively associated with the LA content. These results suggest that the addition of LAB regulated the microbial community in oat silage, which influenced the ensiling products, and LP was more beneficial for decreasing the pH and NH3-N and increasing the LA concentration than LB in forage oat silage.

Influence of Lactobacillus plantarum inoculation on the silage quality of intercropped Lablab purpureus and sweet sorghum grown in saline-alkaline region

Ensiling legume with cereal is an effective method to ensure the energy rich-feed, but no information is available on the microbial fermentation mechanism of intercropped Lablab purpureus (Lablab) and sweet sorghum in the saline-alkaline region. Therefore, the present study investigated the silage quality and microbial community of intercropped Lablab and sweet sorghum silages grown in the saline-alkaline region with or without inoculation of Lactobacillus plantarum (LP). The experimental treatments were prepared according to the Lablab and sweet sorghum planting patterns: Lablab and sweet sorghum sowing seed ratios were 1:1 (L), 5:1 (M), and 9:1 (H). After harvesting, each mixture was treated with LP or sterilized water (CK), followed by 60 days of fermentation. Results showed that both LP inoculation and intercropping significantly raised the lactic acid (LA) content and decreased the pH value, acetic acid (AA), and ammonia-N in intercropped silages. The LP addition and intercropping also improved the relative feed value by reducing structural carbohydrates. Moreover, LP silages had a greater relative abundance of Lactobacillus than CK silages, and its relative abundance increased with an increased seed-sowing ratio of Lablab in intercropping. LP was the prevalent species in LP silages compared to CK silages, and its relative abundance also increased with an increased seed-sowing ratio of Lablab in intercropping. The genus Lactobacillus was negatively correlated with ammonia-N (R = -0.6, p = 0.02) and AA (R = -0.7, p < 0.01) and positively correlated with LA (R = 0.7, p < 0.01) and crude protein (R = 0.6, p = 0.04). Overall, the intercropped seeding ratios of Lablab and sweet sorghum of ≥ 5:1 with LP inoculation resulted in better fermentation quality and preservation of nutritional components providing theoretical support and guidance for future intercropped protein-rich silage production in the saline-alkaline region.

Effect of epiphytic microflora after aerobic enrichment and reconstitution on fermentation quality and microbial community of corn stalk silage and Pennisetum sinese silage

Introduction

The objective of this study was to evaluate the effects of enrichment and reconstitution of the forage epiphytic microflora on the fermentation quality, chemical composition, and bacterial community composition of corn stalk and Pennisetum sinese silages.

Methods

The forage juice of fresh corn stalk and P. sinese were collected, diluted by gradient (10–1 to 10–5), and aerobically incubated to enrich and reconstitute the epiphytic microflora. Fresh corn stalk and P. sinese were ensiled for 3, 15, and 45 days after inoculation with either the original (D0) pre-incubated juices, or 10–1 (D1), 10–3 (D3), or 10–5 (D5) diluted and pre-incubated juices.

Results

The lowest pH was found in the D3 treatment of the corn stalk silage. In P. sinese silage, the hemicellulose content of D3 and D5 treatments was 9.50 and 11.81% lower than that of D0 treatment (P &lt; 0.05). In corn stalk silage, the neutral detergent fiber content was significantly lower in the D3 treatment than in the other treatments (P &lt; 0.05). Both corn stalk and P. sinese silages exhibited a high abundance of Enterobacter during ensiling, resulting in high levels of acetic acid.

Conclusion

Although the dilution and enrichment of the epiphytic microflora did not lead to full lactic acid fermentation, these pre-treatments were found to alter the microbial metabolites and chemical composition of the silage. These results provide a new perspective on the production of pre-fermented silage inoculant.

Effects of Different Soybean and Maize Mixed Proportions in a Strip Intercropping System on Silage Fermentation Quality

Soybean (Glycine max Merr.), with a high nutritional value, is an important oil crop and a good protein feed crop. Due to the shortage of high-protein feed and the high import pressure on soybean, scarce high-protein feed is the main research target for improving feed quality. High-quality soybean (Qihuang 34) and high-yield silage maize (Zea mays L.) (Jingling silage 386) varieties were used as the experimental materials in this study. The silage quality and the microbial community of the mixed silage of soybean and maize were analyzed, and the compatible intercropping ratios of maize–soybean mixed silage were evaluated. This experiment designed five strip intercropping systems (SIS) in a randomized block. The intercropping row ratios of maize and soybean were 0:1 (pure soybean, S), 1:0 (pure maize, M), 1:1 (MS1), 1:3 (MS2), and 1:5 (MS3). Dry matter yield and fresh matter yield were improved in the treatments of MS1 and MS2. In the mixed silage systems of maize and soybean, with an increase in soybean proportion, crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) contents gradually increased, but the contents of water-soluble carbohydrates (WSC) and dry matter (DM) reduced to different degrees (p < 0.05). Moreover, the soybean silage alone had a poor fermentation performance, as indicated by high pH, high acetic acid (AA), propionic acid (PA), butyric acid (BA), and ammonia-N (NH3-N) concentrations, and low lactic acid (LA) concentration. By contrast, the mixed silage materials were conducive to reducing the pH, PA, BA, and NH3-N, and increasing the LA content. The relative abundance of Lactobacillus and Weissella in the MS were higher, and the abundance of undesirable bacteria were lower than in the S. The MS2 materials had the lowest pH, the highest LA concentration, and the highest relative abundance of Lactobacillus and Weissella among the three mixed silage groups. Therefore, the mixed silage in the SIS modified the microbial communities and improved the feed fermentation quality while increasing yields. The better intercropping ratio of maize–soybean mixed silage was 1:3. These results could provide a theoretical basis for the wide application and popularization of soybean as a high-protein silage forage source.

Effects of Acremonium cellulase and heat-resistant lactic acid bacteria on lignocellulose degradation, fermentation quality, and microbial community structure of hybrid elephant grass silage in humid and hot areas

To better evaluate the effects of Acremonium cellulase (AC) and previously screened heat-resistant Lactobacillus plantarum 149 (LP149) on lignocellulose degradation, fermentation quality, and microbial community during ensiling in humid and hot areas, this study used a small-scale fermentation system to prepare hybrid elephant grass silage at 30 and 45°C, respectively. Compared to control and commercial inoculant Lactobacillus plantarum (LP), the addition of AC or strain LP149 decreased the contents of neutral detergent fiber, acid detergent fiber, and cellulose and increased the contents of glucose, fructose, and sucrose during fermentation. Furthermore, AC and LP149 treatments altered the microbial communities' structure during ensiling. AC treatment provided more substrate for microbial fermentation, resulting in an increase in bacterial alpha diversity. LP149 treatment increased the Lactobacillus abundance and optimized the bacterial community compositions. In addition, AC and LP149 treatments had higher (P < 0.05) lactic acid and acetic acid contents and lower (P < 0.05) pH, butyric acid, and NH3-N levels compared to the control. These results indicated that AC and strain LP149 are promising silage additives that can promote lignocellulose degradation and improve the fermentation quality of hybrid elephant grass in humid and hot areas.

Effects of Different Additives on Fermentation Quality, Microbial Communities, and Rumen Degradation of Alfalfa Silage

This study examined the effects of different additives on the fermentation quality, nutrient composition, microbial communities, and rumen degradation of ensiled alfalfa. Six treatments were employed in which additives were applied to alfalfa on a fresh weight basis: CK (no additive), FA (0.6% formic acid), CaO (3% calcium oxide and 3% urea), LB (1 × 106 cfu/g Lentilactobacillus buchneri), GLB (2% glucose and 1 × 106 cfu/g L. buchneri), and FLB (2% fucoidan and 1 × 106 cfu/g L. buchneri). After 60 days of ensiling, all treatments altered the bacterial communities, improved the fermentation quality, reduced dry matter (DM) and crude protein (CP) losses, and enhanced the rumen degradation of nutrients. The addition of LB increased the relative abundance of Lactobacillus spp. (p < 0.05), whereas GLB reduced (p < 0.05) the NH3-N:TN ratio and elevated (p < 0.05) the concentrations of Lactobacillus and lactic acid content. The FA treatment reduced (p < 0.05) the pH, as well as the DM and CP degradations, while the CaO treatment increased the degradations of DM, acid detergent fiber, and neutral detergent fiber. We concluded that FA, LB, GLB, and FLB had beneficial effects on alfalfa fermentation, and that CaO increased alfalfa silage rumen degradation.

Effect of exogenous microorganisms on the fermentation quality, nitrate degradation and bacterial community of sorghum-sudangrass silage

This study aims to investigate the effects of adding Lactobacillus buchneri (LB), Lactobacillus brevis (LBR) and Bacillus subtilis (BS) on the fermentation quality, nitrate degradation and bacterial community of sorghum-sudangrass silage. The results showed that the addition of LB significantly increased the pH and acetic acid content (p < 0.05), but high-quality silage was obtained. The addition of LBR and BS improved the fermentation quality of sorghum-sudangrass silage. The use of additives reduced the nitrate content in sorghum-sudangrass silage. The LB group increased the release of N₂O at 3–7 days of ensiling (p < 0.05), and LBR and BS increased the release of N₂O at 1–40 days of ensiling (p < 0.05). On the first day of ensiling, all silages were dominated by Weisslla, over 3 days of ensiling all silages were dominated by Lactobacillus. Acinetobacter, Serratia, Aquabacterium, and unclassified_f_enterobacteriaceae showed significant negative correlations with nitrate degradation during sorghum-sudangrass ensiling (p < 0.05). The BS and LBR groups increased the metabolic abundance of denitrification, dissimilatory nitrate reduction, and assimilatory nitrate reduction (p < 0.05). Overall, the additive ensures the fermentation quality of sorghum-sudangrass silage and promotes the degradation of nitrate by altering the bacterial community.

Effect of lactic acid bacteria, yeast, and their mixture on the chemical composition, fermentation quality, and bacterial community of cellulase-treated Pennisetum sinese silage

The present study investigated the effects of Lentilactobacillus buchneri, Saccharomyces cerevisiae, and a mixture of the two on the cellulose degradation and microbial community of cellulase-treated Pennisetum sinese (CTPS) during biological pretreatment. The CTPS was stored without additives (CK) or with L. buchneri (L), yeast (Y, S. cerevisiae), and their mixture (LY) under anaerobic conditions for 60 days. All inoculants enhanced the anaerobic fermentation of CTPS. In relative to L, inoculations with Y and LY decreased the cellulose level of fermented-CTPS by 8.90 ~ 17.13%. Inoculation with L inhibited the growth of Weissella cibaria during anaerobic storage. However, inoculations with LY increased the relative abundance of the homofermentative bacterium Lactiplantibacillus plantarum by 6.04%. Therefore, inoculating S. cerevisiae reduced the adverse effects of L. buchneri-stimulated fermentation on cellulose degradation by altering the bacterial community during anaerobic storage of P. sinese. This work provides a new insight for the subsequent anaerobic digestion of P. sinese.

Microbial Community, Co-Occurrence Network Relationship and Fermentation Lignocellulose Characteristics of Broussonetia papyrifera Ensiled with Wheat Bran

Broussonetia papyrifera has a high lignocellulose content leading to poor palatability and low digestion rate of ruminants. Thus, dynamic profiles of fermentation lignocellulose characteristics, microbial community structure, potential function, and interspecific relationships of B. papyrifera mixing with wheat bran in different ratios: 100:0 (BP100), 90:10 (BP90), 80:20 (BP80), and 65:35 (BP65) were investigated on ensiling days 5, 15, 30, and 50. The results showed that adding bran increased the degradation rate of hemicellulose, neutral detergent fiber, and the activities of filter paper cellulase, endoglucanase, acid protease, and neutral protease, especially in the ratio of 65:35. Lactobacillus, Pediococcus, and Weissella genus bacteria were the dominant genera in silage fermentation, and Pediococcus and Weissella genus bacteria regulated the process of silage fermentation. Compared with monospecific B. papyrifera silage, adding bran significantly increased the abundance of Weissella sp., and improved bacterial fermentation potential in BP65 (p < 0.05). Distance-based redundancy analysis showed that lactic acid bacteria (LAB) were significantly positive correlated with most lignocellulose content and degrading enzymes activities, while Monascus sp. and Syncephalastrum sp. were opposite (p < 0.05). Co-occurrence network analysis indicated that there were significant differences in microbial networks among different mixing ratios of B. papyrifera silage prepared with bran. There was a more complex, highly diverse and less competitive co-occurrence network in BP65, which was helpful to silage fermentation. In conclusion, B. papyrifera ensiled with bran improved the microbial community structure and the interspecific relationship and reduced the content of lignocellulose.

Effects of different cutting methods and additives on the fermentation quality and microbial community of Saccharum arundinaceum silage

To develop a new high-yielding and polysaccharide-containing forage resource for livestock, the effects of different cutting methods and additives on Saccharum arundinaceum silage were evaluated. The wilted S. arundinaceum were chopped and knead-wired. The silages from each cutting method were treated with Lactobacillus plantarum (LP), cellulase (CE) and the combination of LP and CE (LP + CE) for 3, 7, 15, 30, and 60 days. Compared with the CK treatment, CE treatment exhibited better effects in the degradation of neutral detergent fiber (NDF), LP exhibited a better performance in preserving the content of dry matter (DM), and adding LP + CE significantly enhanced (P &lt; 0.05) the contents of lactic acid (LA), crude protein (CP) and DM and significantly reduced (P &lt; 0.05) the pH and NDF content during ensiling. In addition, both additives exerted a remarkable effect on the silage bacterial community (P &lt; 0.05), with a dramatic increase in the Lactobacillus abundance and a decrease in the abundance of Enterobacter. Lactic acid bacteria (LAB) became the most dominant bacteria that affected the fermentation quality of LP and LP + CE silages. Meanwhile, chopped silages showed better fermentation quality and nutrient preservation and a higher abundance of LAB. Our research indicated that the chopped S. arundinaceum ensiling with LP + CE could exert a positive effect on LA fermentation and preservation of nutrient substances by shifting the bacterial community. In conclusion, S. arundinaceum can serve as a new silage resource for feed utilization by the ensiling method of LP + CE-chopped.

Effects of different additives on the bacterial community and fermentation mode of whole-plant paper mulberry silage

The purpose of this study was to investigate the effects of inoculation with two lactic acid bacteria (LAB) strains (Lacticaseibacillus rhamnosus and Lentilactobacillus buchneri) and the addition of four corn flour proportions (0, 3, 6, and 9%) in different treatments, on the composition and function of the bacterial community in whole-plant paper mulberry silage. The different treatments promoted Lactiplantibacillus, Lentilactobacillus, and Lacticaseibacillus growth, but the microbial species responsible for fermentation differed among the treatments. High species diversity and various Gram-negative bacteria, such as Flavitalea sp., Pantoea agglomerans, Acinetobacter pittii, Turicibacter sanguinis, and Ralstonia pickettii, were found in the uninoculated LAB treatments. A beneficial bacterium, Lactobacillus johnsonii, was discovered for the first time in whole-plant paper mulberry silage. LAB inoculation simplifies the microbial community structure, and beneficial Lactobacillus as a key species aggregates in the inoculated treatment group. However, L. rhamnosus inoculation alone may have limited bacteriostatic activity against in whole-plant paper mulberry silage. Compared with silage lacking corn flour, amino sugar and nucleotide sugar metabolism, galactose metabolism, the phosphotransferase system and the pentose phosphate pathway metabolic activity were increased in corn flour-containing silage. Whole-plant paper mulberry can be used as a high-quality silage to provide high-quality feed resources for sustainable ruminant livestock production. Moreover, additive use is necessary for preparing paper mulberry silage.