Laboratory silo type and inoculation effects on nutritional composition, fermentation, and bacterial and fungal communities of oat silage

A comparative evaluation of maize silage quality under diverse pre-ensiling strategies

Maize silage serves as a significant source of energy and fibre for the diets of dairy and beef cattle. However, the quality of maize silage is contingent upon several crucial considerations, including dry matter loss, fermentative profile, pH level, ammonia content, and aerobic stability. These aspects are influenced by a multitude of factors and their interactions, with seasonality playing a crucial role in shaping silage quality. In this study an open-source database was utilised to assess the impact of various pre-ensiling circumstances, including the diversity of the chemical composition of the freshly harvested maize, on the silage quality. The findings revealed that seasonality exerts a profound influence on maize silage quality. Predictive models derived from the composition of freshly harvested maize demonstrated that metrics were only appropriate for screening purposes when utilizing in-field sensor technology. Moreover, this study suggests that a more comprehensive approach, incorporating additional factors and variability, is necessary to better elucidate the determinants of maize silage quality. To address this, combining data from diverse databases is highly recommended to enable the application of more robust algorithms, such as those from machine learning or deep learning, which benefit from large data sets.

The Effects of Lactobacillus plantarum and Lactobacillus buchneri on the Fermentation Quality, In Vitro Digestibility, and Aerobic Stability of Silphium perfoliatum L. Silage

In this experiment, Lactobacillus plantarum and Lactobacillus buchneri were added individually or in combination to Silphium perfoliatum L. (SP) silage to investigate the effects of different fermentation types of lactobacilli on the fermentation quality, in vitro digestibility, and aerobic stability of SP-silage, with a view to providing a certain scientific basis and technical support for obtaining high-quality SP-silage in production. The experiment comprised a non-additive group (control), an L. plantarum group (LP), an L. buchneri group (LB), and an L. plantarum and L. buchneri mixed treatment group (LPLB). Samples were taken after 60 days of fermentation and analyzed for the fermentation quality, in vitro digestibility, and aerobic stability of the SP-silage. The results showed that the addition of LP, LB, and LPLB significantly reduced the pH and proportion of ammonia nitrogen to total nitrogen and significantly increased the lactic acid, in vitro dry matter digestibility, and in vitro crude protein digestibility in the SP-silage (p < 0.05). Compared to the control group, the dry matter and crude protein contents of the LB and LPLB groups were significantly increased, while the neutral detergent fiber and acid detergent fiber contents were significantly reduced (p < 0.05). The SP-silage supplemented with LPLB had the highest dry matter and crude protein contents. The gross and digestible energies of the SP-silage in the LB and LPLB groups were significantly higher than those in the control and LP groups (p < 0.05). The aerobic stability of the SP-silage was significantly reduced by 24.14% in the LP group and increased by 58.62% and 34.48% in the LB and LPLB groups, respectively, compared to the control group (p < 0.05). It was shown that adding a combination of LP and LB resulted in the best fermentation quality, nutritional value, and in vitro digestibility of the SP-silage. LB was effective in improving the aerobic stability of SP-silage.

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.

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.

Biomass yield, quality, nutrient composition, and feeding value of oat (Avena sativa) silage subjected to different wilting durations and/or inoculant application

In this study, we evaluated the biomass yield, physico-chemical characteristics, nutrient composition, and feeding value of oat (Avena sativa) grown without irrigation ensiled with or without supplemental inoculant following different wilting durations. Oat forage at early dough stage (79 days after sowing) were harvested to assess the biomass yield, nutrient contents, and mineral composition. Oats were ensiled with or without the addition of inoculant and different wilting durations (0, 24, and 48 h) in 3 × 2 factorial arrangement. After the ensiling (120 days), the oat silages were opened, quality was measured in terms of pH, ammonia nitrogen (NH3-N), smell, structure, color, and Flieg point. Nutritional composition and feeding values were analyzed in oat silages. Oat grown without irrigation yielded 32 ton/ha fresh matter. Mean dry matter (DM), organic matter, crude protein (CP), crude fiber, crude ash, ether extract, nitrogen free extract, acid detergent fiber (ADF), neutral detergent fiber, acid detergent lignin, non-structural carbohydrates, hemicellulose, and in vitro dry matter digestibility of oat forage were 32.77%, 90.41%, 11.31%, 28.69%, 9.59%, 3.99%, 46.43%, 36.32%, 63.98%, 7.22%, 11.14%, 27.67%, and 74.81%, respectively. Addition of inoculant had no effect on the quality, nutritional composition, and feeding values of oat silages. Increasing wilting durations linearly increased the pH (P = 0.005) and decreased the smell score (P = 0.028) of ensiled oat. A linear increase was seen in the DM content of ensiled oat after increasing wilting durations (P = 0.001). Oat ensiled without wilting had greater CP content (P = 0.010 and linear P = 0.011) and lower ADF content than those ensiled after 24 or 48 h of wilting (P = 0.013 and linear P = 0.007). Silages subjected to 24 or 48 h of wilting had lower hemicellulose content (P = 0.019 and linear P = 0.012) and digestible DM (P = 0.013 and linear P = 0.007) than those without wilting. In conclusion, inoculant may not affect the quality, composition and feeding values of ensiled oat grown without irrigation whereas, wilting at different durations may negatively affect the pH, smell, CP, ADF, and feeding values of ensiled oats.

Ensiling hybrid Pennisetum with lactic acid bacteria or organic acids improved the fermentation quality and bacterial community

The aim of this study was to compare the effect of different additives on nutritional quality, fermentation variables and microbial diversity of hybrid Pennisetum silages. A control (CK - no additives) and seven treatments were tested, namely, Lactiplantibacillus plantarum (LP), Lentilactobacillus buchneri (LB), propionic acid (PA), calcium propionate (CAP), LP + LB; LP + PA and LP + CAP. In comparison with CK, all treatments increased the contents of crude protein and lactic acid, decreased the content of butyric acid, and altered the bacterial communities of the silage. Except for the CAP and LP + CAP treatments, the additives decreased pH and the ammonia nitrogen:total nitrogen (NH₃-N:TN) ratio. The results of principal component analysis revealed that the PA, LP + PA and LP + LB treatments ranked as the top three silages. The PA and LP + PA treatments exhibited higher water-soluble carbohydrate content, but lower pH, and NH₃-N:TN ratio than the other treatments. With the PA and LP + PA treatments, the relative abundances of Lactobacillus and Enterobacter decreased, and of Proteobacteria and Delftia increased, while the carbohydrate metabolism of the microorganisms improved. The LP and LB treatments reduced the Shannon and Simpson diversities. In the beta diversity, PA and LP + PA separated from the other treatments, indicating that there were differences in the composition of bacterial species. The relative abundance of Lactobacillus increased in the LP and LB treatments and of Leucanostoc and Weissella increased in the CAP and LP + CAP treatments. In summary, the addition of L. plantarum, L. buchneri, propionic acid, calcium propionate, and their combinations improved fermentation quality, inhibited harmful bacteria and conserved the nutrients of hybrid Pennisetum.

Community Synergy of Lactic Acid Bacteria and Cleaner Fermentation of Oat Silage Prepared with a Multispecies Microbial Inoculant

To investigate community synergy of lactic acid bacteria (LAB) and cleaner fermentation of oat silage, oat silages were prepared with or without (control) commercial LAB inoculants LI1 (containing Lactiplantibacillus plantarum, Lentilactobacillus buchneri, Lacticaseibacillus paracasei, and Pediococcus acidilactici) and LI2 (containing Lactiplantibacillus plantarum and Lentilactobacillus buchneri). The microbial community, LAB synergy, and cleaner fermentation were analyzed at 1, 3, 6, 15, 35, and 90 days of ensiling. The LAB inoculant improved fermentation quality, with significantly (P < 0.05) lower pH, ammonia nitrogen content, and gas production and higher lactic acid and acetic acid contents than those of the control. Enterobacteriaceae was the main bacterial community in early stage of fermentation, which utilizes sugar to produce CO2 gas, causing dry matter (DM) and energy loss. As fermentation progressed, the microbial diversity decreased, and the microbial community shifted from Gram-negative to Gram-positive bacteria. The inoculation of multispecies LAB displayed community synergy; Pediococcus acidilactici formed a dominant community in the early stage of fermentation, which produced an acid and anaerobic environment for the subsequent growth of Lentilactobacillus and Lacticaseibacillus species, thus forming a LAB-dominated microbial community. The predicted functional profile indicated that the silage inoculated with LI1 enhanced the carbohydrate metabolism pathway but inhibited the amino acid metabolism pathway, which played a role in promoting faster lactic acid production, reducing the decomposition of protein to ammonia nitrogen, and improving the fermentation quality of silage. Therefore, oat silage can be processed to high-quality and cleaner fermented feed by using an LAB inoculant, and LI1 showed better efficiency than LI2. IMPORTANCE Oat natural silage is rich in Enterobacteriaceae, increasing gas production and fermentation loss. Lactic acid bacteria interact synergistically to form a dominant community during ensiling. Pediococci grow vigorously in the early stage of fermentation and create an anaerobic environment. Lactobacilli inhibit the harmful microorganisms and result in cleaner fermentation of oat silage.

Integrated Microbiota and Metabolome Analysis to Assess the Effects of the Solid-State Fermentation of Corn-Soybean Meal Feed Using Compound Strains

Solid-state fermentation is known to improve plant-based feed nutritional quality; however, the association between microbes and metabolite production in fermented feed remains unclear. We inoculated corn-soybean-wheat bran (CSW) meal feed with Bacillus licheniformis Y5-39, Bacillus subtilis B-1, and lactic acid bacteria RSG-1. Then, 16S rDNA sequencing and untargeted metabolomic profiling were applied to investigate changes in the microflora and metabolites, respectively, and their integrated correlations during fermentation were assessed. The results indicated that trichloroacetic acid soluble protein levels showed a sharp increase, while glycinin and β-conglycinin levels showed a sharp decrease in the fermented feed, as confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Pediococcus, Enterococcus, and Lactobacillus were predominant in the fermented feed. Overall, 699 significantly different metabolites were identified before and after fermentation. Arginine and proline, cysteine and methionine, and phenylalanine and tryptophan metabolism were the key pathways, with arginine and proline metabolism being the most important pathway in the fermentation process. By analyzing the correlation between the microbiota and metabolite production, lysyl-valine and lysyl-proline levels were found to be positively correlated with Enterococcus and Lactobacillus abundance. However, Pediococcus was positively correlated with some metabolites contributing to nutritional status and immune function. According to our data, Pediococcus, Enterococcus, and Lactobacillus mainly participate in protein degradation, amino acid metabolism, and lactic acid production in fermented feed. Our results provide new insights into the dynamic changes in metabolism that occurred during the solid-state fermentation of corn-soybean meal feed using compound strains and should facilitate the optimization of fermentation production efficiency and feed quality.

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.

A meta-analysis to observe silage microbiome differentiated by the use of inoculant and type of raw material

Silage fermentation is naturally carried out by lactic acid bacteria (LAB) to mainly produce lactic acid (LA) and other organic acids as preservatives. Along with fermentation time, the growth of LAB will replace and suppress undesirable microorganisms. This meta-analysis study aimed to explore silage microbiome differentiated by LAB inoculants and type of raw materials. A total of 37 articles with 185 studies and 475 datasets were used for building up the meta-database. Data were subjected to the mixed model methodology. The parameters observed were silage quality and silage microbiome post-ensiling process. Results revealed that four bacterial genera along with Weissella dominated the post-ensiling process. The addition of lactic acid inoculants in the silage has increased the abundance of Lactobacillus spp. and decreased the Shannon index significantly. Moreover, the abundance of both L. plantarum and L. buchneri increased, and subsequently, Weissella, Pseudomonas, Proteobacteria, pH value, ammoniacal nitrogen (NH₃-N), coliforms, and the yeasts were decreased significantly due to the addition of LAB inoculants in silage (p < 0.05). Environmental factors such as temperature affected the existence of Pseudomonas, Exiguobacterium, and Acinetobacter. However, the dry matter, LA, acetic acid (AA), the ratio of LA to AA, and the LAB population were enhanced significantly (p < 0.05). Among the LAB types, the lowest abundance of Pseudomonas was due to the LAB group, while the lowest abundance of Weissella and Proteobacteria was due to the addition of the combined LAB group. In conclusion, the addition of LAB is effectively enhancing the silage microbiome and silage quality by altering bacterial diversity and the metabolic products of the silage materials for safe preservation.

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

The presence of undesirable microorganisms in silage always leads to poor fermentation quality and low aerobic stability. Pyroligneous acid (PA), a by-product of biochar production, is known to have strong antimicrobial and antioxidant activities. To investigate the effects of PA on fermentation characteristics, aerobic stability, and microbial communities, Napier grass was ensiled with or without 1 and 2% PA for 30 days and then aerobically stored for 5 days. The results showed that PA application decreased (P < 0.01) the pH value, ammonia nitrogen content, and number of undesirable microorganisms (coliform bacteria, yeasts, and molds) after 30 days of ensiling and 5 days of exposure to air. The temperature of the PA-treated group was stable during the 5-day aerobic test, which did not exceed room temperature more than 2°C. The addition of PA also enhanced the relative abundance of Lactobacillus and reduced that of Klebsiella and Kosakonia. The relative abundance of Candida was higher in PA-treated silage than in untreated silage. The addition of PA decreased the relative abundance of Kodamaea and increased that of Monascus after 5 days of exposure to air. The abundances of Cladosporium and Neurospora were relatively high in 2% PA-treated NG, while these genera were note observed in the control group. These results suggested that the addition of PA could improve fermentation characteristics and aerobic stability, and alter microbial communities of silage.

Effects of antibacterial peptide-producing Bacillus subtilis, gallic acid, and cellulase on fermentation quality and bacterial community of whole-plant corn silage

In the current study, we assessed the effects of antibacterial peptide-producing Bacillus subtilis (BS), gallic acid (GA) and cellulase (CL) on the fermentation quality and bacterial community of various varieties of whole-plant corn silage. Three different varieties of whole-plant corn (Yuqing386, Enxiai298, and Nonghe35) were treated with 0.02% BS (fresh material basis), 0.2% GA (fresh material basis) and 0.02% CL (fresh material basis), after which 45 days of anaerobic fermentation were conducted. With the exception of its low dry matter content, the results showed that Yuqing386's crude protein, water-soluble carbohydrate, and lactic acid contents were significantly higher than those of the other two corn varieties. However, its acid detergent fiber and cellulose contents were significantly lower than those of the other two corn varieties. Among the three corn variety silages, Yuqing386 had the highest relative abundance of Lactobacillus at the genus level and the biggest relative abundance of Firmicutes at the phylum level. In addition, the three additives markedly enhanced the quantity of dry matter and crude protein as compared to the control group. The application of GA considerably decreased the level of neutral detergent fiber while significantly increasing the content of lactic acid and water-soluble carbohydrates. Even though all additives enhanced the structure of the bacterial community following silage, the GA group experienced the greatest enhancement. On a phylum and genus level, the GA group contains the highest relative abundance of Firmicutes and Lactobacillus, respectively. Overall, of the three corn varieties, Yuqing386 provides the best silage qualities. GA has the biggest impact among the additions employed in this experiment to enhance the nutritional preservation and fermentation quality of whole-plant corn silage.

Microbiome of rehydrated corn and sorghum grain silages treated with microbial inoculants in different fermentation periods

Due to the co-evolved intricate relationships and mutual influence between changes in the microbiome and silage fermentation quality, we explored the effects of Lactobacillus plantarum and Propionibacterium acidipropionici (Inoc1) or Lactobacillus buchneri (Inoc2) inoculants on the diversity and bacterial and fungal community succession of rehydrated corn (CG) and sorghum (SG) grains and their silages using Illumina Miseq sequencing after 0, 3, 7, 21, 90, and 360 days of fermentation. The effects of inoculants on bacterial and fungal succession differed among the grains. Lactobacillus and Weissella species were the main bacteria involved in the fermentation of rehydrated corn and sorghum grain silage. Aspergillus spp. mold was predominant in rehydrated CG fermentation, while the yeast Wickerhamomyces anomalus was the major fungus in rehydrated SG silages. The Inoc1 was more efficient than CTRL and Inoc2 in promoting the sharp growth of Lactobacillus spp. and maintaining the stability of the bacterial community during long periods of storage in both grain silages. However, the bacterial and fungal communities of rehydrated corn and sorghum grain silages did not remain stable after 360 days of storage.

Exploring the effect of wilting on fermentation profiles and microbial community structure during ensiling and air exposure of king grass silage

In order to better understand the effect of wilting treatment on silage, we study analyzed the fermentation quality of unwilted (CK) and wilted (WT) king grass silage, and the dynamic changes of microorganisms in silage and aerobic exposure. After 30 days of silage, WT silage significantly reduced the pH of the silage (p < 0.05) and increased the contents of lactic acid and acetic acid (p < 0.05), but did not reduce the content of Ammonia-N (p > 0.05). Wilting treatment increased bacterial and fungal diversity during silage but decreased fungal diversity during aerobic exposure. The relative abundance of Lactococcus and Enterococcus in wilting silage increased. In the aerobic exposure stage, the relative abundance of Klebsiella decreased, but the relative abundance of Enterobacter increased in wilting treatment silage. In addition, the relative abundance of Acinetobacter and Ignatzschineria increased after 5 days of aerobic exposure. In contrast with unwilted silage, wilting treatment silage after aerobic exposure had no Candida, but the relative abundance of Wickerhamomyces increased. The results showed that wilting treatment could raise the silage quality of king grass. However, WT silage did not inhibit the reproduction of harmful microorganisms during aerobic exposure and did not significantly improve the aerobic stability of silage.

Effects of Lactic Acid Bacteria Additives on the Quality, Volatile Chemicals and Microbial Community of Leymus chinensis Silage During Aerobic Exposure

Silage exposed to air is prone to deterioration and production of unpleasant volatile chemicals that can seriously affect livestock intake and health. The aim of this study was to investigate the effects of Lactobacillus plantarum (LP), Lactobacillus buchneri (LB), and a combination of LP and LB (PB) on the quality, microbial community and volatile chemicals of Leymus chinensis silage at 0, 4, and 8 days after aerobic exposure. During aerobic exposure, LP had higher WSC and LA contents but had the least aerobic stability, with more harmful microorganisms such as Penicillium and Monascus and produced more volatile chemicals such as Isospathulenol and 2-Furancarbinol. LB slowed down the rise in pH, produced more acetic acid and effectively improved aerobic stability, while the effect of these two additives combined was intermediate between that of each additive alone. Correlation analysis showed that Actinomyces, Sphingomonas, Penicillium, and Monascus were associated with aerobic deterioration, and Weissella, Pediococcus, Botryosphaeria, and Monascus were associated with volatile chemicals. In conclusion, LB preserved the quality of L. chinensis silage during aerobic exposure, while LP accelerated aerobic deterioration.

Effects of Different Concentrations of Lactobacillus plantarum and Bacillus licheniformis on Silage Quality, In Vitro Fermentation and Microbial Community of Hybrid Pennisetum

The purpose of the experiment was to study the effects of different concentrations of Lactobacillus plantarum (LP) and Bacillus licheniformis (BL) on the quality of hybrid Pennisetum (HP) silage. The experiment consisted of five 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) and 1 × 107 cfu/g FW, respectively. The results showed that LP and BL could increase the in vitro fermentation gas production and reduce the ammonia nitrogen (AN) content in HP silage. Water-soluble carbohydrates (WSC), lactic acid (LA) content, and gas production in the LP group were positively correlated with LP addition, and acetic acid (AA) was negatively correlated with addition. The content of WSC and LA in the LP7 group was significantly higher than that in the control group (p < 0.05), and AA was lower than that in the control group (p > 0.05). Dry matter (DM), crude protein (CP), and gas production were negatively correlated with the addition of BL, while acid detergent fiber (ADF) content was positively correlated with the addition of BL. Furthermore, in the above indicators, the BL5 group reached a significant level with the control group (p < 0.05). The results of 16sRNA showed that the use of LP and BL could increase the relative abundance of Lactobacillus and decrease the relative abundance of Weissella in HP silage compared with the control group. In conclusion, LP and BL can significantly improve the quality of HP silage. The LP7 group and the BL5 group have the best silage effect. From the perspective of gas production in in vitro fermentation, the LP7 group had stronger fermentability and higher nutritional value.

Assessment on the Fermentation Quality and Bacterial Community of Mixed Silage of Faba Bean With Forage Wheat or Oat

Faba bean (Vicia faba L.), although a kind of high-quality and high-yield forage, could hardly achieve a great quality of silage because of its high buffering capacity. Mixed silage of faba bean with forage wheat (Triticum aestivum L.) or oat (Avena sativa L.) at different ratios could improve the fermentation quality and bacterial community. Compared with 100% faba bean silage (BS), mixed silage improved the fermentation quality, not only increased lactic acid production and reduced pH, but reduced the production of propionic acid and ammonia nitrogen. The chemical compositions of faba bean with forage wheat (BT) mixed silage were better than that of faba bean with oat (BO) mixed silage, and that of 3:7, 5:5 (fresh matter basis) mixing ratios were better than 1:9. However, the fermentation quality of BO mixed silage was better than that of BT, and that of 3:7 mixed silage (BO30) was the best overall. Analysis of the bacterial community showed that mixed silage increased the relative abundance of lactic acid bacteria after ensiling, and the relatively higher abundance of Lactobacillus showed the inhibitory effects on the proliferation of Serratia and Hafnia_Obesumbacterium, so that it alleviated their negative effects on silage and stabilized the fermentation quality. This present study exhibited that mixed silage of faba bean with forage wheat or oat not only had significant effects on chemical compositions and fermentation quality of materials but modified bacterial community so that improved the fermentation quality effectively. The mixed silage of 30% faba bean with 70% oat (BO30) is recommended in the faba bean mixed silage.

Fermentation Characteristics and Microbiota during the Ensiling of Myriophyllum aquaticum Inoculated with Lactic Acid Bacteria

Myriophyllum aquaticum (M. aquaticum) is a commonly used aquatic macrophyte for water purification and could be utilized as animal food. However, the high water content of M. aquaticum makes it difficult for long-term preservation, which leads to challenges as an ideal animal feed ingredient. The storage of Silage for long periods may be a proper method to solve the problem. In the present paper, we assess the effects of lactic acid bacteria Lactobacillus buchneri (LB), Lactobacillus plantarum (LP), or their combination on fermentation and microbial communities during the ensiling of M. aquaticum silage. The results show that the LP-treated silage displays a higher lactic acid concentration than that in the control silage. Both LB and LP increased the abundance of Lactobacillus, but decreased the abundance of Serratia and Prevotella_9 in M. aquaticum silage after 60 days of ensiling. Both LB and LP increased the diversity and richness of fungi. Therefore, the inoculation of LP improved silage fermentation during ensiling. These results show that the inoculation of lactic acid bacteria improves the fermentation quality of M. aquaticum silage, which makes it possible for the application of M. aquaticum to animal forage in the future.

Improved performance and microbial community dynamics in anaerobic fermentation of triticale silages at different stages

Production of high-quality grass-based silages by microbial-mediated anaerobic fermentation is an effective strategy in livestock farms. In the present study, an ensiling process was used to preserve and enhance fermentative metabolites in triticale silages with novel inoculants of Lactobacillus rhamanosus -52 and, Lactobacillus rhamanosus-54. Triticale silages treated with LAB predominantly had lower pH values than control silages due to rapid changes of microbial counts. LAB addition improved anaerobic fermentation profiles showing higher lactic acid, but lower acetic acid and butyric acid concentrations. A background microbial dynamic study indicated that the addition of L. rhamanosus-52 and L. rhamanosus-54 improved silage fermentation, enriched Lactobacillus spp., and decreased microbial richness with diversity, leading to increased efficiency of lactic acid fermentation. In conclusion, LAB treatment can increase silage quality by enhancing the dominance of desirable Lactobacillus while inhibiting the growth of undesirable microbes.

Effects of applying cellulase and starch on the fermentation characteristics and microbial communities of Napier grass (Pennisetum purpureum Schum.) silage

This study investigated the effects of applying cellulase and starch on the fermentation characteristics and microbial communities of Napier grass silage after ensiling for 30 d. Three groups were studied: No additives (control); added cellulase (Group 1); and added cellulase and starch (Group 2). The results showed that the addition of cellulase and starch decreased the crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and pH significantly (p < 0.05) and increased water-soluble carbohydrate (WSC) content (p < 0.05). The addition of additives in two treated groups exerted a positive effect on the lactic acid (LA) content, lactic acid bacteria (LAB) population, and lactic acid / acetic acid (LA/AA) ratio, even the changes were not significant (p > 0.05). Calculation of Flieg’s scores indicated that cellulase application increased silage quality to some extent, while the application of cellulase and starch together significantly improved fermentation (p < 0.05). Compared with the control, both additive groups showed increased microbial diversity after ensiling with an abundance of favorable bacteria including Firmicutes and Weissella, and the bacteria including Proteobacteria, Bacteroidetes, Acinetobacter increased as well. For alpha diversity analysis, the combined application of cellulase and starch in Group 2 gave significant increases in all indices (p < 0.05). The study demonstrated that the application of cellulase and starch can increase the quality of Napier grass preserved as silage.

Propionic Acid and Sodium Benzoate Affected Biogenic Amine Formation, Microbial Community, and Quality of Oat Silage

Investigating the microbial communities and biogenic amine (BA) formation in silage is of vital for improving the quality and safety of oat silage. The present study evaluated the effects of propionic acid (P) and sodium benzoate (SB) on the quality properties, microbial communities, and BA formation in oat silage. Oat was harvested at boot stage and ensiled using P and SB as additives in mini silos, followed by 14 days of aerobic exposure. The results showed that P and SB improved fermentation quality of oat silage, increased the lactic acid content, and decreased pH value and ammonia nitrogen content. Putrescine, cadaverine, and tyramine were the dominant BAs in oat silage; spermidine and spermine were not detected. The control silage had the highest content of total biogenic amine (TBA, 2506.7 mg kg^–1 DM), and decreased by 51.1 and 57.7% after adding P and SB, respectively. Moreover, a lower putrescine, cadaverine, and tyramine content and undesirable microbes, such as Caproiciproducens, Stenotrophomonas, Herbinix, and Enterobacter genera, were observed in P and SB silages, which was beneficial for oat silage quality. The fungal community of P silage was dominated by Monascus fuliginosus, and the temperature, pH and ammonia nitrogen content increased after exposure to air. Sedimentibacter, Herbinix, Caproiciproducens, Enterobacter, and Escherichia-Shigella were found to be positively correlated with BA formation in oat silage. Overall, P and SB effectively inhibit the undesirable microbes and BA formation in oat silage, the P silage exhibited lower aerobic stability than the SB silage.

Microbial Community and Fermentation Characteristics of Native Grass Prepared Without or With Isolated Lactic Acid Bacteria on the Mongolian Plateau

This study aimed to isolate and identify lactic acid bacteria (LAB) from the native grass and naturally fermented silage from the Mongolian Plateau. The effect of selected strains on bacterial community and quality of native grass silage was also studied. Strains XM2, 265, and 842 could grow normally at 15°C–30°C, pH 4.0–8.0, and NaCl 3 and 6.5%; they were identified as Lactiplantibacillus plantarum subsp. plantarum, Pediococcus acidilactici, and Latilactobacillus graminis, by sequencing 16S rRNA, respectively. The three strains (XM2, 265, and 842) and one commercial additive (L) were used as inoculants and singularly added to the native grass. Compared to the control, the dry matter content was significantly (p < 0.05) lower in L and XM2 groups. The water-soluble carbohydrate content was significantly (p < 0.05) higher in control than in other groups. Compared with the control, the crude protein and ammonia nitrogen contents were significantly (p < 0.05) higher and lower in the LAB-treated groups, and the acid and detergent fiber contents were significantly (p < 0.05) reduced in the L and XM2 groups than those in other groups. There was a significant (p < 0.05) difference in the pH value, lactic acid content, and lactic acid-to-acetic acid ratio in L and XM2 groups than in other groups. Compared with the control, the number of LAB was significantly (p < 0.05) higher in LAB-treated silages, whereas no significant (p > 0.05) differences were observed in yeast and aerobic bacteria in all groups. Compared to the control, the Shannon index was significantly (p < 0.05) reduced. Simpson and Chao1 were significantly (p < 0.05) increased. Principal coordinate analysis based on the unweighted UniFrac distance showed clear separation of the bacterial community in fresh materials and LAB-treated silages. Besides, compared to the control, the principal coordinate analysis of LAB-treated silages was also separate. After 30 days of fermentation, the relative abundance of Firmicutes increased and was the primary phylum in all silages. Compared with the control, the abundance of Firmicutes and Proteobacteriawas significantly (p < 0.05) higher and lower in L and XM2 groups. In contrast, no significant differences were observed among control, 265, and 842 groups. At the genus level, the relative abundance of Lactobacillus, Enterobacter, Pediococcus, and Weissella was increased and dominated the native grass fermentation. Compared with the control, the abundance of Lactobacillus was significantly (p < 0.05) higher in L, XM2, and 842 groups, while no significant (p > 0.05) differences were observed between the control and 265 groups. The abundance of Pediococcus was higher than that in other groups. Consequently, the results demonstrated that LAB significantly influenced silage fermentation by reconstructing microbiota, and Lactobacillus was the dominant genus in the native grass silages. Furthermore, the results showed that strain XM2 could effectively improve the silage quality, and it is considered a potential starter for the native grass silage.

Effect of Lactic Acid Bacteria on the Fermentation Quality and Mycotoxins Concentrations of Corn Silage Infested with Mycotoxigenic Fungi

This study was conducted to evaluate the effect of lactic acid bacteria (LAB) on fermentation quality, mycotoxin concentrations, and microbial communities of whole-crop corn silages infested with mycotoxigenic fungi. Cultured spores (10⁶ cfu/mL) of mycotoxigenic Aspergillus flavus and Fusarium graminearum were sprayed (5 mL) on corn forage on 27 July and 10 August 2018. On 21 August 2018, sprayed (FI; 3 plots) and unsprayed (NFI; 3 plots) corn forage were harvested at the 1/2 kernel milk line stage, followed by chopping and ensiling without inoculants (CON), or with Lactobacillus buchneri (LB, 1 × 10⁶ cfu/g FW), Lactobacillus plantarum (LT, 1 × 10⁶ cfu/g FW), or L. buchneri + L. plantarum (BT: both L. buchneri and L. plantarum applied at 0.5 × 10⁶ cfu/g FW). After 90 d of ensiling, FI silages had a higher (p < 0.05) pH value and higher acetic acid (ACA), ethanol, and ammonia nitrogen (ammonia N) concentrations, but lower (p < 0.05) lactic acid (LA) concentrations than NFI silage. The inoculants decreased pH and increased LA concentration and LA/ACA compared with CON. The aflatoxin B₁ (AFB₁) was only detected in FI fresh corn and silages; ensiling decreased (p < 0.05) AFB₁ concentration compared with fresh corn, and LB and BT decreased AFB₁ concentration compared with CON. The zearalenone (ZEN), deoxynivalenol (DON), and fumonisin B₁ (FB₁) concentrations were similar (p < 0.05) for NFI silages, while ZEN concentration in BT was the lowest (p < 0.05) among all FI silages; DON and FB₁ concentrations in LB, LT, and BT silages were significantly lower (p < 0.05) than those of CON in FI silages. The fungal infestation increased the bacterial and fungal diversity of silages compared with NFI silages. The FI silages had a higher relative abundance (RA) of Lactobacillus, Weissella, Wickerhamomyces, Pichia, and Epicoccum than the corresponding NFI silages. The RA of Aspergillus and Fusarium markedly decreased after 90 d of ensiling, and the inoculation expanded this trend irrespective of fungal infestation. The Penicillium in FI silages survived after 90 d of ensiling, while the inoculants decreased the RA of Penicillium. Inoculants mitigate the adverse effects of fungal infestation on corn silage quality by changing the bacterial and fungal communities.

Effect of Lactobacillus hilgardii, Lactobacillus buchneri, or their combination on the fermentation and nutritive value of sorghum silage and corn silage

The objective of this study was to determine the effect of inoculation with Lactobacillus hilgardii with or without Lactobacillus buchneri on the fermentation, chemical composition, and aerobic stability of sorghum and corn silage after 2 ensiling durations. Sorghum forage was harvested at 27% dry matter (DM; experiment 1), and different corn hybrids were harvested at late (43.8% DM; experiment 2) or normal maturity (34% DM; experiment 3). All harvested forages were chopped and ensiled in quadruplicate in vacuum-sealed nylon-polyethylene bags (40 × 61 cm) for 30 and 90 d after treatment with (1) deionized water (uninoculated) or (2) L. buchneri (1.5 × 10⁵ cfu/g of fresh weight; LB); (3) L. hilgardii (1.5 × 10⁵ cfu/g of fresh weight; LH); or (4) L. buchneri and L. hilgardii (1.5 × 10⁵ cfu/g of fresh weight of each inoculant). Data for each experiment were analyzed separately accounting for the 2 × 2 × 2 factorial treatment arrangement. Inoculating sorghum forage with LB or LH separately increased acetate and 1,2 propanediol concentration, tended to increase DM loss, reduced lactate concentration and the lactate-to-acetate ratio, and increased aerobic stability after 90 but not after 30 d of ensiling. Inoculating late-harvested corn silage with LB or LH separately increased and decreased DM loss, respectively, increased 1,2 propanediol concentration, reduced lactate-to-acetate ratio and yeast counts but did not affect aerobic stability. Inoculating normal-harvested corn silage with LH reduced DM loss and increased 1,2 propanediol concentration and yeast counts; LB reduced lactate concentration, lactate-to-acetate ratio, and total acids. Either inoculant alone increased aerobic stability after 30 or 90 d. The main benefit of combining LB with LH was prevention of increases in DM losses by LH or LB separately. No improvement in aerobic stability resulted from applying LH instead of LB separately or from combining them. Application of LB or LH separately improved aerobic stability of sorghum silage after 90 d and normal-harvested corn silage after 30 or 90 d but did not affect that of late-harvested corn silage.

Microbial Communities, Metabolites, Fermentation Quality and Aerobic Stability of Whole-Plant Corn Silage Collected from Family Farms in Desert Steppe of North China

Whole-plant corn silages on family farms were sampled in Erdos (S1), Baotou (S2), Ulanqab (S3), and Hohhot (S4) in North China, after 300 d of ensiling. The microbial communities, metabolites, and aerobic stability were assessed. Lactobacillusbuchneri, Acinetobacter johnsonii, and unclassified Novosphingobium were present at greater abundances than others in S2 with greater bacterial diversity and metabolites. Lactobacillus buchneri, Lactobacillus parafarraginis, Lactobacillus kefiri, and unclassified Lactobacillus accounted for 84.5%, and 88.2%, and 98.3% of bacteria in S1, S3, and S4, respectively. The aerobic stability and fungal diversity were greater in S1 and S4 with greater abundances of unclassified Kazachstania, Kazachstania bulderi, Candida xylopsoci, unclassified Cladosporium, Rhizopus microspores, and Candida glabrata than other fungi. The abundances of unclassified Kazachstania in S2 and K. bulderi in S3 were 96.2% and 93.6%, respectively. The main bacterial species in S2 were L. buchneri, A. johnsonii, and unclassified Novosphingobium; Lactobacillus sp. dominated bacterial communities in S1, S3, and S4. The main fungal species in S1 and S4 were unclassified Kazachstania, K. bulderi, C. xylopsoci, unclassified Cladosporium, R. microspores, and C. glabrata; Kazachstania sp. dominated fungal communities in S2 and S3. The high bacterial diversity aided the accumulation of metabolites, and the broad fungal diversity improved the aerobic stability.

Using molecular microbial ecology to define differential responses to the inoculation of barley silage

Previously, we investigated the impact of a mixed Lactobacillus buchneri, Lactobacillus plantarum, and Lactobacillus casei inoculant on fermentation and aerobic stability of barley silage over two years in 2009 and 2010. In 2009, a classical response to inoculation was obtained with an increase in acetic acid concentration of silage ensiled in both mini- and bag silos. In 2010, this classical response was not observed in mini-silos but was observed in bag silos. The objective of this study was to determine if molecular microbial ecology could explain the differential responses to the inoculation of barley silage between the two years. The Illumina MiSeq sequencing results showed that inoculation increased Lactobacillus and lowered Pediococcus, Weissella, and Leuconostoc in both types of silos in 2009. However, a similar trend was not observed in mini-silos, but was instead observed in bag silos in 2010. Inoculation did not alter the core fungal community in either silo type in either year. Cladosporium, Leptosphaeria, and Cryptococcus were abundant in fresh forage, but were superseded by Pichia and Kazachstania after ensiling. Our results suggest that changes in silage chemistry corresponded to differences observed in microbial ecology. Inoculation may have less impact when using more mature crops with shorter ensiling times.

Effects of a chemical additive on the fermentation, microbial communities, and aerobic stability of corn silage with or without air stress during storage

We evaluated the effects of a chemical additive on the microbial communities, fermentation profile, and aerobic stability of whole-plant corn silage with or without air stress during storage. Whole-plant corn was either untreated or treated with a chemical additive containing sodium benzoate, potassium sorbate, and sodium nitrite at 2 or 3 liters/t of fresh forage weight. Ten individually treated and replicated silos (7.5 liters) were made for each treatment. Half of the silos remained sealed throughout a 63-d storage period, and the other half was subjected to air stress for 2 h/wk. The composition of the bacterial and fungal communities of fresh forage and silages untreated or treated with 2 liters/t of fresh forage weight was analyzed by Illumina Miseq sequencing. Treated silage had greater (P < 0.05) aerobic stability than untreated, even when subjected to air stress during storage, but the numbers of yeasts culturable on selective agar were not affected. However, the additive reduced the relative abundance (RA) of the lactating-assimilating yeast Candida tropicalis (P < 0.01). In air-stressed silages, untreated silage had a greater (P < 0.05) RA of Pichia kudriavzevii (also a lactate assimilator) than treated silage, whereas treated silage was dominated by Candida humilis, which is usually unable to assimilate lactate or assimilates it slowly. The additive improved the aerobic stability by specifically preventing the dominance of yeast species that can consume lactate and initiate aerobic spoilage. To the best of our knowledge, this is the first work that identifies the specific action of this additive on shifting the microbial communities in corn silage.

Silage Fermentation, Bacterial Community, and Aerobic Stability of Total Mixed Ration Containing Wet Corn Gluten Feed and Corn Stover Prepared with Different Additives

Simple Summary

Wet corn gluten feed (WCGF) is a feed containing high moisture and rapidly digestible, non-forage fiber and protein for dairy cows, that is difficult to preserve. The use of corn stover as roughage by ruminants is limited by its poor digestibility. Total mixed ration (TMR) silage is an ensiling mixed feed that can fully mix forage and concentrate in a specific ratio to satisfy the nutritional needs of dairy cows, which has become an effective method of preservation of high-moisture byproducts. The objective of this study was to investigate the effects of different additives on the fermentation quality, bacterial community, and aerobic stability of TMR silage containing WCGF and corn stover. Inoculation with lactic acid bacteria (LAB) + fibrolytic enzyme (EN) and LAB improved aerobic stability of TMR silages indicated by higher and more stable LA and AA contents, a smaller rise in pH, and yeast count than other silages. Total mixed ration silage inoculated the LAB + EN and LAB can become an effective method of preserving high-moisture WCGF and corn stover with poor digestibility.

Abstract

The objective of this study was to investigate the effects of different additives on the fermentation quality, bacterial community, and aerobic stability of total mixed ration (TMR) silage containing wet corn gluten feed (WCGF) and corn stover. The TMR was ensiled with four treatments: (1) no additive (control); (2) lactic acid bacteria (LAB); (3) fibrolytic enzyme (EN); (4) LAB + EN. The EN and LAB + EN decreased the neutral detergent fiber and acid detergent fiber contents. Additives led to a higher lactic acid (LA) content (p < 0.0001) compared to control at all ensiling times. Silages inoculated with LAB and LAB + EN had higher dry matter (p = 0.0007), LA (p < 0.0001) and acetic acid (AA) contents (p < 0.0001) compared to control. The LAB and LAB + EN had significantly lowest ammonia nitrogen among the treatments, while no significant difference occurred after days 7 of ensiling. Silages treated with LAB and LAB + EN had a higher LAB count (p < 0.0001) and a lower pH, yeast, and mold counts compared to other silages. The LAB and LAB + EN greatly increased the portions of Firmicutes and Lactobacillus (p < 0.0001, and p < 0.0001, respectively) and reduced undesirable bacteria. Inoculation with LAB + EN and LAB improved aerobic stability of TMR silages indicated by higher and more stable LA and AA contents, smaller rise in pH, and yeast count than other silages. The LAB + EN and LAB reduced microbial diversity and improved the fermentation quality and aerobic stability of TMR silage containing WCGF and corn stover.

Inoculation of exogenous lactic acid bacteria exerted a limited influence on the silage fermentation and bacterial community compositions of reed canary grass straw on the Qinghai-Tibetan Plateau

AIMS

This study evaluated the effects of exogenous lactic acid bacteria (LAB) on silage fermentation and bacterial community of reed canary grass (RCG) straw.

METHODS AND RESULTS

The leaf, stem and whole crop of RCG straw were separately ensiled in small bag silos, without (control) or with inoculation of two exogenous LAB (LP, Lactobacillus plantarum; LB, Lactobacillus buchneri), and stored at ambient temperature of <20°C. Inoculation of exogenous LAB decreased (P < 0·05) bacterial alpha diversity and shifted (P < 0·05) bacterial community compositions, but did not change (P> 0·05) the relative abundance of Lactobacillus. Particularly, inoculation of LB increased (P < 0·05) acetic acid and propionic acid contents, decreased (P < 0·05) butyric acid (BA) and ammonia-N contents, separated (P < 0·05) the bacterial community in silage. However, the exogenous LAB inoculated silages were characterized by main distribution of yeasts, presence of undesirable bacterial genera such as Clostridium and high levels of BA and ammonia-N.

CONCLUSION

Inoculation of exogenous LAB exerted a limited influence on the silage fermentation and bacterial community compositions of RCG straw on the Qinghai-Tibetan Plateau.

SIGNIFICANCE AND IMPACT OF THE STUDY

Commercial LAB inoculants are not always efficient on enhancing silage quality and stability. Thus, an alternative additive for inhibiting undesirable microbes during storage is important to improve RCG silage quality on the Qinghai-Tibetan Plateau.

Impact of molasses and microbial inoculants on fermentation quality, aerobic stability, and bacterial and fungal microbiomes of barley silage

This study aimed to investigate the effects of microbial inoculants (L) and molasses (M) on the bacterial and fungal microbiomes of barley silage after the aerobic stage. The addition of molasses and microbial inoculants improved the aerobic stability of barley silage. The ML silage, which had a low pH value and high lactic and acetic acid contents, remained aerobically stable for more than 216 h. The ML silage exhibited low bacterial and high fungal diversities. Microbial inoculants and molasses enriched the abundance of Lactobacillus in silage after aerobic exposure. The enrichment of L. buchneri was significant in ML silage at days 5 and 7 during the aerobic stage. The abundance of harmful microorganisms, such as aerobic bacterial including Acinetobacter, Providencia, Bacillus, and yeasts including Issatchenkia, Candida, and Kazachstania, were suppressed in ML silage. M and L had an impact on bacterial and fungal microbes, resulting in the improvement of fermentation quality and reduction of aerobic spoilage in barley silage.

Effects of microbial inoculants on the fermentation characteristics and microbial communities of sweet sorghum bagasse silage

Sweet sorghum bagasse (SSB) is a promising raw material for silage fermentation due to its high residual nutritive, but the efficient fermentation strategy of SSB has not been reported yet. This study evaluated the effects of microbial inoculant on the fermentation quality, chemical composition and microbial community of SSB silage. The silage inoculated with isolated lactic acid bacteria (LpE) achieved better fermentation than that of commercial inoculant A, B (CIA, CIB) and untreatment, including low pH value, high levels of lactic acid and water soluble carbohydrates (WSC) content, which demonstrated that the LpE inoculant could contribute to the preservation of nutrition and the manipulation of fermentation process of SSB. In addition, the results of microbial community analysis indicated that the LpE inoculant significantly changed the composition and diversity of bacteria in SSB silage. After ensiling, the LpE inoculated silage were dominated by Lactobacillus(95.71%), Weissella(0.19%). These results were of great guiding significance aiming for high-quality silage production using SSB materials on the basis of target-based regulation methods.

Ensilability, in vitro and in vivo values of the agro-industrial by-products of artichoke and broccoli

By-products of raw artichoke (RA) (Cynara scolymus L.) and boiled broccoli (BB) (Brassica oleracea, var. italica) were ensiled in plastic bags for 24 days. Then, chemical composition, nutritive characteristics, in vitro rumen degradability, in vivo digestibility and phytosanitary residue contents of the silages were evaluated. The fermentative parameters studied indicated that plastic bags were a suitable method to silage RA and BB by-products. Both silages had a high in vitro rumen DM disappearance at 72 h, although it was higher in the BB silage (96.8 vs. 82.1%). In vivo digestibility of DM was similar and high in both silages (78.5 and 80.0% in RA and BB), but crude protein and NDF digestibilities were higher in the BB silage (83.0 and 88.3% vs. 55.1 and 78.8%). No residues of analysed phytosanitary were found. In conclusion, silages of wastes from the processing of artichoke and broccoli were free from the analysed several phytosanitary residues, their nutritive value made them adequate for feeding ruminant animals and are an environmentally friendly way of disposal of such residues.

Effects of a high-dose Saccharomyces cerevisiae inoculum alone or in combination with Lactobacillus plantarum on the nutritional composition and fermentation traits of maize silage

Context The inoculation of silage with Saccharomyces cerevisiae to deliver viable yeast cells is a novel concept. Aims The effects of a high-dose S. cerevisiae inoculum alone or combined with Lactobacillus plantarum on the nutritional composition, fermentation traits and aerobic stability of maize silage were studied after 30, 60 and 90 days of storage. Methods Whole-crop maize (309.3 g dry matter (DM)/kg as fed) was subjected to one of three treatments: deionised water (untreated control); S. cerevisiae at an estimated concentration of 108 CFU/g fresh forage (S); or S. cerevisiae at an estimated concentration of 108 CFU/g and L. plantarum at an estimated concentration of 105 CFU/g of fresh forage (SL). Key results Compared with the control, the S and SL groups showed increases (P &lt; 0.001) in average pH (3.98 in S and 4.01 in SL vs 3.65 in the control), crude protein (85 g/kg DM in S and 80 g/kg DM in SL vs 63 g/kg DM in the control) and ammonia nitrogen/total nitrogen (122.2 g/kg in S and 163.9 g/kg in SL vs 52.9 g/kg in the control) but a lower (P &lt; 0.001) average concentration of water-soluble carbohydrate (0.9 g/kg DM in S and 0.7 g/kg DM in SL vs 2.3 g/kg DM in the control). The levels of neutral detergent fibre and acid detergent fibre were greater (P &lt; 0.001) in S silage than in the control and SL silages, and the hemicellulose level was lower (P = 0.004) in the SL group than the control and S groups. Starch and aerobic stability were unaffected by treatment, and the average lactate and ethanol concentrations were higher (P &lt; 0.001) in the S (53.7 g lactate/kg DM and 28.7 g ethanol/kg DM) and SL (56.9 g lactate/kg DM and 21.4 g ethanol/kg DM) groups than the control (40.1 g lactate/kg DM and 5.3 g ethanol/kg DM) over 90 days of ensiling. Conclusions Overall, a high-dose inoculum of S. cerevisiae alone or combined with L. plantarum affected the nutritional composition and fermentation traits of maize silage. Implications The inoculation of maize silage with a high dose of S. cerevisiae needs to be performed with caution.

Dynamic Succession of Microbiota during Ensiling of Whole Plant Corn Following Inoculation with Lactobacillus buchneri and Lactobacillus hilgardii Alone or in Combination

Lactic acid bacteria (LAB) used as silage additives have been shown to improve several fermentation parameters, including aerobic stability. Inoculation with a combination of Lactobacillus buchneri NCIMB40788 and Lactobacillus hilgardii CNCM-I-4785, contributes to an increase in aerobic stability, compared to each strain inoculated independently. To understand the mode of action of the combination on the LAB community, a fermentation-kinetic study was performed on corn. Four treatments, Control, Lb. buchneri,Lb. hilgardii, and a combination of the two strains, were fermented 1, 2, 4, 8, 16, 32, and 64 days. Corn silage inoculated by both strains had a lactate:acetate ratio of 0.59 after 64 days and a higher concentration of lactate than Lb. buchneri. Analysis of the microbiota by 16S and ITS amplicon metasequencing demonstrated that inoculation led to lower bacterial diversity after 1 day, from 129.4 down to 40.7 observed operational taxonomic units (OTUs). Leuconostocaceae represented the dominant population by day 1, with 48.1%. Lactobacillaceae dominated the succession by day 4, with 21.9%. After 32 days, inoculation by both strains had the lowest bacterial alpha diversity level, with 29.0 observed OTUs, compared to 61.3 for the Control. These results confirm the increased fermentation efficiency when the two Lactobacillus strains are co-inoculated, which also led to a specific yeast OTUs diversity profile, with Hannaella as the main OTU.

Analysis of the correlation between bacteria and fungi in sugarcane tops silage prior to and after aerobic exposure

The correlation between bacteria and fungi in sugarcane tops silage prior to and after aerobic exposure was analyzed. The results showed that the abundance of Lactobacillus increased from 0.03% to 27.84% from d 0-60. Additionally, the abundance of Pichia also increased from 0.003% to 15.46% from d 0-60. Following aerobic exposure, the abundance of Lactobacillus increased by 42.39% at d 3. Moreover, Pichia was the dominant fungal genus after aerobic exposure. Spearman's correlation analysis showed that Pichia was positively correlated with the genera Lactobacillus and Pediococcus, but negatively correlated with the genera Acinetobacter, Citrobacter, and Serratia. Aspergillus, Cladosporium, and Fusarium were positively correlated with the genera Clostridium, Lactobacillus, and Pediococcus, but negatively correlated with the genera Acinetobacter, Citrobacter, and Serratia. Spearman's correlation also suggested that Aspergillus, Cladosporium, and Fusarium could be inhibited by screening Serratia, thereby reducing mycotoxins in silage.

Sweet Corn Stalk Treated with Saccharomyces Cerevisiae Alone or in Combination with Lactobacillus Plantarum: Nutritional Composition, Fermentation Traits and Aerobic Stability

This study examined the effects of a high-dose Saccharomyces cerevisiae inoculant alone or jointly with Lactobacillus plantarum on nutrient preservation, fermentation quality, and aerobic stability of sweet corn stalk silage. Fresh stalks (231 g dry matter (DM)/kg) were chopped and subjected to the following treatments: (1) deionized water (Uninoculated; U); (2) S. cerevisiae at 1 × 10⁸ cfu/g of fresh forage (S); and (3) S. cerevisiae at 1 × 10⁸ cfu/g plus L. plantarum at 1 × 10⁵ cfu/g (SL). Treated stalks were ensiled in 5-litre laboratory silos for 30, 60, and 90 d. The S and SL silages had a greater (p < 0.001) pH and greater crude protein, ammonia nitrogen/total nitrogen, neutral detergent fibre, acid detergent fibre, and ethanol contents at all three ensiling periods than the U silage. Acetate, propionate and volatile fatty acids in the S and SL silages after 30 and 90 d of ensiling were greater (p < 0.05) than those in the U silage, but they were lower (p < 0.05) in the S and SL silages than in the U silage after 60 d. The lactate and V-score of the S and SL silages were lower (p < 0.001) than those of the U silage at all three ensiling periods. Compared with the U group, the aerobic stability of the S silage after 90 d of ensiling decreased (p < 0.05), and the aerobic stability of the SL silage was unaffected (p > 0.05). Overall, the quality of sweet corn stalk silage was not improved by inoculation with 10⁸ cfu/g of S. cerevisiae alone or in combination with 1 × 10⁵ cfu/g of L. plantarum.

Dynamics of Bacterial Community and Fermentation Quality during Ensiling of Wilted and Unwilted Moringa oleifera Leaf Silage with or without Lactic Acid Bacterial Inoculants

Moringa oleifera leaf is a high-quality feed source for livestock and is increasingly used all over the world. Ensiling might be an effective method for preservation of the leaves. In the practice of silage making, lactic acid bacterial inoculants and wilting are commonly used to improve nutrition preservation. Monitoring the changes in a bacterial community during fermentation gives an insight into understanding and improving the ensiling process. Our results suggest that wilting and lactic acid bacterial inoculants had an influence on the bacterial community and fermentation process of M. oleifera leaf silage. Wilting showed positive effects on silage fermentation by decreasing the abundance of Enterobacter spp., while LF and LL improved the fermentation quality by inhibiting Enterobacter spp. and enhancing Lactobacillus spp. Both LF and LL accelerated the ensiling process from cocci (like Lactococcus, Enterococcus, and Leuconostoc spp.) to lactobacilli.

To investigate the effects of wilting and lactic acid bacterial inoculants on the fermentation quality and bacterial community of Moringa oleifera leaf silage, fresh and wilted M. oleifera leaves were ensiled with or without Lactobacillus farciminis LF or Lactococcus lactis LL for 1, 7, 14, 30, and 60 days. The results showed that wilting, inoculants, and their interaction exerted significant (P < 0.05) effects on the fermentation characteristics covering dry matter loss, pH value, lactic acid bacterial number, the ratio of lactic acid to acetic acid, and the relative abundances of bacteria, like for species of Lactobacillus, Lactococcus, Pediococcus, Enterococcus, Leuconostoc, and Enterobacter. Both LF and LL improved the fermentation quality of wilted and unwilted M. oleifera leaf silage by accelerating lactic acid production and pH decline, decreasing dry matter loss, and inhibiting yeast and coliform bacterial growth through the whole fermentation process. During ensiling, the abundances of Lactococcus, Enterococcus, and Leuconostoc spp. increased from day 1 to day 7 and then declined sharply from day 7 to day 14. Members of these genera and Enterobacter were inhibited, whereas Lactobacillus spp. were enhanced by these two lactic acid bacterial inoculants. The relative abundances of Enterobacter, Enterococcus, and Pediococcus spp. in inoculated silages were relatively low during the whole ensiling process. A lower abundance of Enterobacter spp. was observed in wilted silages than in unwilted silages. In summary, wilting and lactic acid bacterial inoculants had an influence on bacterial community and the fermentation process; LF and LL improved the fermentation quality of wilted and unwilted M. oleifera leaf silage.

IMPORTANCEMoringa oleifera leaf is a high-quality feed source for livestock and is increasingly used all over the world. Ensiling might be an effective method for preservation of the leaves. In the practice of silage making, lactic acid bacterial inoculants and wilting are commonly used to improve nutrition preservation. Monitoring the changes in a bacterial community during fermentation gives an insight into understanding and improving the ensiling process. Our results suggest that wilting and lactic acid bacterial inoculants had an influence on the bacterial community and fermentation process of M. oleifera leaf silage. Wilting showed positive effects on silage fermentation by decreasing the abundance of Enterobacter spp., while LF and LL improved the fermentation quality by inhibiting Enterobacter spp. and enhancing Lactobacillus spp. Both LF and LL accelerated the ensiling process from cocci (like Lactococcus, Enterococcus, and Leuconostoc spp.) to lactobacilli.

Bacterial Dynamics of Wheat Silage

Knowledge regarding bacterial dynamics during crop ensiling is important for understanding of the fermentation process and may facilitate the production of nutritious and stable silage. The objective of this study was to analyze the bacterial dynamics associated with whole crop wheat silage with and without inoculants. Whole crop wheat was ensiled in laboratory silos, with and without Lactobacillus inoculants (L. plantarum, L. buchneri), for 3 months. Untreated and L. plantarum-treated silages were sampled at several times during ensiling, while L. buchneri-treated silage was sampled only at 3 months. Bacterial composition was studied using next generation sequencing approach. Dominant bacteria, before ensiling, were Pantoea (34.7%), Weissella (28.4%) and Pseudomonas (10.4%), Exiguobacterium (7.8%), and Paenibacillus (3.4%). Exogenous inoculants significantly affected bacterial composition and dynamics during ensiling. At 3 months of ensiling, Lactobacillus dominated the silage bacterial population and reached an abundance of 59.5, 92.5, and 98.2% in untreated, L. plantarum- and L. buchneri-treated silages, respectively. The bacterial diversity of the mature silage was lower in both treated silages compared to untreated silage. Functional profiling of the bacterial communities associated with the wheat ensiling demonstrated that the abundant pathways of membrane transporters, carbohydrate and amino acids metabolisms followed different pattern of relative abundance in untreated and L. plantarum-treated silages. Only three pathways, namely base-excision repair, pyruvate metabolism and transcription machinery, were significantly different between untreated and L. buchneri-treated silages upon maturation. Lactic acid content was higher in L. plantarum-treated silage compared to untreated and L. buchneri-treated silage. Still, the pH of both treated silages was lower in the two Lactobacillus-treated silages compared to untreated silage. Aerobic stability test demonstrated that L. plantarum-, but not L. buchneri-supplement, facilitated silage deterioration. The lower aerobic stability of the L. plantarum-treated silage may be attributed to lower content of acetic acid and other volatile fatty acids which inhibit aerobic yeasts and molds. Indeed, high yeast count was recorded, following exposure to air, only in L. plantarum-treated silage, supporting this notion. Analysis of bacterial community of crop silage can be used for optimization of the ensiling process and the selection of appropriate inoculants for improving aerobic stability.

Dynamics of a microbial community during ensiling and upon aerobic exposure in lactic acid bacteria inoculation-treated and untreated barley silages

This study investigated the effects of lactic acid bacteria on bacterial and fungal community during the fermentation process and aerobic exposure phase of barley ensiled with preparation of lactic acid bacteria (LAB). The inoculated silages displayed higher contents of lactic acid, acetic acid, and propionic acid as well as a greater number of lactic acid bacteria during ensiling. LAB-treated silage decreased the bacterial diversity during both ensiling and aerobic exposure but increased the fungal diversity during ensiling of barley. LAB-treated silage during ensiling increased the abundance of Lactobacillus but decreased that of Weissella. After aerobic exposure, LAB-treated silage increased the abundance of Lactobacillus but decreased that of Acinetobacter. Acinetobacter, Enterococcus, Providencia, and Empedobacter were the dominant bacteria after aerobic exposure. In conclusion, LAB-treated silage enhanced the number of desirable Lactobacillus and inhibited the growth of undesirable microorganisms, such as Acinetobacter.

Fermentation characteristics, chemical composition and microbial community of tropical forage silage under different temperatures

Objective

In tropical regions, as in temperate regions where seasonality of forage production occurs, well-preserved forage is necessary for animal production during periods of forage shortage. However, the unique climate conditions (hot and humid) and forage characteristics (high moisture content and low soluble carbohydrate) in the tropics make forage preservation more difficult. The current study used natural ensiling of tropical forage as a model to evaluate silage characteristics under different temperatures (28°C and 40°C).

Methods

Four tropical forages (king grass, paspalum, white popinac, and stylo) were ensiled under different temperatures (28°C and 40°C). After ensiling for 30 and 60 days, samples were collected to examine the fermentation quality, chemical composition and microbial community.

Results

High concentrations of acetic acid (ranging from 7.8 to 38.5 g/kg dry matter [DM]) were detected in silages of king grass, paspalum and stylo with relatively low DM (ranging from 23.9% to 30.8% fresh material [FM]) content, acetic acid production was promoted with increased temperature and prolonged ensiling. Small concentrations of organic acid (ranging from 0.3 to 3.1 g/kg DM) were detected in silage of white popinac with high DM content (50.8% FM). The microbial diversity analysis indicated that Cyanobacteria originally dominated the bacterial community for these four tropical forages and was replaced by Lactobacillus and Enterobacter after ensiling.

Conclusion

The results suggested that forage silages under tropical climate conditions showed enhanced acetate fermentation, while high DM materials showed limited fermentation. Lactobacillus and Enterobacter were the most probable genera responsible for tropical silage fermentation.