Silage processing and strategies to prevent persistence of undesirable microorganisms

Metagenome analyses reveal the role of Clostridium perfringens in alfalfa silage anaerobic deterioration

The clostridial fermentation caused by the outgrowth of Clostridia was mainly responsible for the silage anaerobic deterioration. Our previous results showed that Clostridium perfringens dominated the clostridial community in poor-fermented alfalfa silage. This study was conducted to further examine the role of C. perfringens in silage anaerobic deterioration through fermentation products and the microbial community analyses. Direct-cut alfalfa was ensiled with C. perfringens contamination (CKC) or with the addition of Lactobacillus plantarum, sucrose and C. perfringens (LSC). Contamination with C. perfringens enhanced the clostridial fermentation in CKC silage, as indicated by high contents of butyric acid, ammonia nitrogen and Clostridia, while LSC silage was well preserved. The genera Bifidobacterium, Garciella and Clostridium dominated the bacterial community in CKC silage, while predominate genus was replaced by Lactobacillus in LSC silage. The clostridial community in CKC silage was dominated by Garciella sp. (26.9 to 58.1%) and C. tyrobutyricum (24.4 to 48.6%), while the relative abundance of C. perfringens was below 5.0%. Therefore, the effect of Clostridia contamination on ensiling fermentation was dependent on the ensilability of the silage material. Garciella sp. and C. tyrobutyricum, rather than C. perfringens, played dominant role in the clostridial fermentation in CKC silage.

Effect of temperature on single- and mixed-strain fermentation of ruminant feeds

Use of raw feedstuffs for livestock is limited by low digestibility. Recently, fermentation of feedstuffs has been highlighted as a new way to improve nutrient absorption through the production of organic acids using inoculated microorganisms, which can also play a probiotic role. However, standard procedures for feedstuff fermentation have not been clearly defined because the process is influenced by climatic variation, and an analytical standard for fermented feedstuffs is lacking. This study aimed to evaluate the microbiological and biochemical changes of feedstuffs during fermentation at temperatures corresponding to different seasons (10°C, 20°C, 30°C, and 40°C). We also investigated the effects of yeast, lactic acid bacteria (LAB), and Bacillus spp. on fermentation and determined the results of their interactions during fermentation. The viable cells were observed within 8 days in single-strain fermentation. However, when feedstuffs were inoculated with a culture of mixed strains, LAB were predominant at low temperatures (10°C and 20°C), while Bacillus spp. was predominant at high temperatures (30°C and 40°C). A significant drop in pH from 6.5 to 4.3 was observed when LAB was the dominant strain in the culture, which correlated with the concentrations of lactic acid. Slight ethanol production was detected above 20°C regardless of the incubation temperature, suggesting active metabolism of yeast, despite this organism making up a marginal portion of the microbes in the mixed culture. These results suggested that fermentation temperature significantly affects microbiological profiles and biochemical parameters, such as pH and the lactic acid concentration, of fermented feedstuffs. Our data provide valuable information for the determination of industrial standards for fermented feedstuffs.

Effects of different simulated seasonal temperatures on the fermentation characteristics and microbial community diversities of the maize straw and cabbage waste co-ensiling system

Ensiling is considered as a suitable method to preserve seasonal agricultural residues to enable long-term supply for wastes valorization. In this study, the effects of simulated seasonal temperatures (-3, 18 and 34 °C) on the organic compositions, ensiling fermentation characteristics, and microbial community evolution during 120 days co-ensiling of maize straw and cabbage wastes were investigated. Successful storage performance was obtained at all these three temperatures. Comparatively, silages at 18 and 34 °C showed lower ammonia nitrogen, lower pH and more intensive lactic acid bacteria fermentation than that at -3 °C. Both silages at -3 and18 °C were well-preserved for 120 days with higher biodegradation potential (BDP), accompanied by lower content of acid detergent lignin (ADL). However, the silages at 34 °C could only preserved for 90 days due to low carbohydrate, low BDP and higher ADL content than that at -3 or18 °C. The storage temperature is a critical parameter that significantly affected the silage quality by influencing the microbial community diversity in silages. Proteobacteria and Firmicutes were dominant bacteria at phylum level for all silages while the dominant lactic acid bacteria at genus level were Lactobacillus and Leuconostoc, which restrained the undesirable microbes such as Enterobacteriaceae, Pseudomonas, Flavobacterium, and Pantoea during co-ensiling. Co-ensiling of maize straw with vegetable wastes may provide a promising strategy for long-term preservation of air-dried crop straw while using vegetable wastes as regulatable supplement to achieve silages of desired quality. This study could provide valuable information for conservation and management of agricultural wastes.

Effects of fermentative and non-fermentative additives on silage quality and anaerobic digestion performance of Pennisetum purpureum

The effect of additives on the silage quality, microbial community, and anaerobic digestion performance of Pennisetum purpureum with high moisture content was studied. The sample treated with a mixed additive had best silage quality with the lowest pH and highest lactic acid/acetic acid ratio. Different additives influenced the dominant desirable bacteria. Correspondingly, Enterobacter was the dominant bacterial genus for sample with non-fermentative additives, whereas for the samples with fermentative or mixed additives, both Enterobacter and Lactobacillus had high relative abundance. The parameters of NH₃-N, hemicellulose and lactic acid were positively correlated with the specific methane yield, while the lignin content was inversely correlated with the specific methane yield. The higher specific methane yield of 293.81 ± 0.15-334.69 ± 22.75 mL/g VS was obtained for samples treated with fermentative additive. Therefore, the mixed additive and fermentative additive are recommended for the silage of material with high-moisture content to improve the silage quality and methane yield.

The effect of an additive containing three Lactobacillus species on the fermentation pattern and microbiological status of silage

BACKGROUND

Appropriate combinations of lactic acid bacteria (LAB) strains should be selected to optimize the ensiling process, and the additives should be adjusted to the ensiled forage crops. The aim of this study was to determine the effect of inoculation with three Lactobacillus species on the chemical parameters and microbiological quality (beneficial and harmful microbiota) of grass silage.

RESULTS

Three species: L. paracasei (LPa), L. brevis (LB) and L. plantarum (LPl), isolated from sugar beet silage and characterized based on 16S rDNA sequences and biochemical parameters, were analyzed in the study. Single strains and their combinations were used as silage inoculants. The basic chemical and microbiological (qPCR) parameters of silages were determined. Based on the results of agglomerative hierarchical clustering (AHC) and principal component analysis (PCA) it was determined that silages inoculated with single LAB strains and LPa + LB and commercial additive (0+) were the best quality ones, particularly with regard to microbiological parameters and they effectively lowered the pH value. A consortium of three Lactobacillus species had no influence on silage quality, whereas LPa + LB and LPl + LB combinations as well as a commercial additive exerted positive effects. Inoculation inhibited the growth of toxin-producing fungi.

CONCLUSION

Only the appropriate LAB composition can improve the quality of the ensiled material (antagonistic relationship). Only the LPa + LB combination was able to improve the value of low dry silage; nevertheless, almost all combinations were able to reduced concentrations of toxin-producing fungi. © 2019 Society of Chemical Industry.

Ensilability of Biomass From Effloresced Flower Strips as Co-substrate in Bioenergy Production

Flower strips are grown to an increasing degree in order to enhance the ecological value of agricultural landscapes. Depending on their profitable life span and the crop sequence, the strips' biomass must be mulched after flowering to enable repeated tillage. A promising alternative is the use of the flower strips' biomass as a co-substrate for biomethanisation - thereby contributing to the climate-friendly generation of energy. This potential bioenergy substrate occurs only seasonally and is commonly produced only in limited quantities at a farm scale. To realize the additional benefit of flower strips as energy suppliers, stock piling of the strips' biomass is required. However, information about the ensilability of flower strip biomass is still rare. We conducted a 2-year study to analyze the ensilability of pure biomass from effloresced flower strips and mixtures of flower strip biomass with 33 and 67% whole crop maize, respectively. Ensiling took place in 3 l model silos at laboratory scale after chopping the substrate. Before ensiling several chemical characteristics of the biomass stock were determined to assess the substrate's biochemical ensilability potential (dry matter content, water-soluble carbohydrates, buffering capacity, nitrate content). The process-engineered ensiling success after 90 days was determined based on fermentation patterns. The ensilability potential of the pure flower strip substrates reached modest levels (fermentability coefficients according to Weißbach vary around the threshold of 45). Nevertheless, acceptable silage qualities were achieved under the laboratory conditions (pH ranging from 4.2 to 4.7). Compared to pure flower strip biomass, the addition of maize noticeably improved both the substrate's biochemical ensilability potential and the quality of real fermented silage. We conclude that a mixture of 33% biomass from flower strips with 67% whole crop maize can be regarded as a recommendable ratio if proper ensiling technology is applied.

A mixture of potassium sorbate and sodium benzoate improved fermentation quality of whole-plant corn silage by shifting bacterial communities

AIMS

To investigate the changes in fermentation quality of whole-plant corn silage ensiled with varying dosages of mixed organic acid salts (MS), and link these dosage changes to shifts in bacterial composition.

METHODS AND RESULTS

Fermentation quality and bacterial community of corn silage ensiled with MS at four application rates (0, 0·67 g kg^-1 , 1·33 g kg^-1 , and 2·00 g kg^-1 ) were investigated. The MS consisted of 40% potassium sorbate and 60% sodium benzoate. The corn silages were conserved for 42 days. Dry matter losses and ammonia nitrogen concentration were linearly declined by up to 19·10 and 33·3% with increasing dosages of MS. MS treatments significantly reduced the pH of silage vs the control group. Further analysis indicated that the improvement of fermentation quality was the result of shifts in bacterial composition, the relative abundance of Lactobacillus paralimentarius and Pediococcus spp. increased while Lactobacillus reuteri, Lactobacillus coryniformis and Klebsiella declined with increasing dosages of MS.

CONCLUSIONS

MS effectively improved the fermentation quality of whole-plant corn silage with an optimum dosage of 2·00 g kg^-1 .

SIGNIFICANCE AND IMPACT OF THE STUDY

The correlation between bacterial taxa and fermentation quality provides a potential for the development of novel silage inoculants and for the application of MS on controlling Klebsiella mastitis of livestock farms.

Gallic acid influencing fermentation quality, nitrogen distribution and bacterial community of high-moisture mulberry leaves and stylo silage

To investigate the feasibility of vegetal gallic acid (GA) improving silage quality, fermentation parameter, nitrogen distribution and bacterial community of mulberry leaves and stylo ensiled with 1% and 2% GA were analyzed after 60-d fermentation. The results showed that GA addition decreased dry matter loss (6.08% vs 5.35%, 17.79% vs 11.56% in mulberry leaves and style silage, respectively), pH (6.51 vs 5.98, 5.55 vs 4.57), butyric acid (0.41% and 0.83% DM, undetected in GA groups) and ammonia-N (0.71% vs 0.19%, 1.46% vs 0.29% TN) contents and increased lactic acid (2.27% vs 6.68%, 0.91% vs 1.91% DM) and acetic acid (1.68% vs 3.20%, 0.97% vs 2.02% DM) contents. Meanwhile, the relative abundance of Clostridium or Enterobacter was decreased, and that of lactate-producing bacteria was increased in mulberry leaves and stylo silage. In conclusion, GA could be used as a green additive to improve fermentation quality and protein preservation during ensiling.

Ensiling characteristics, proteolysis and bacterial community of high-moisture corn stalk and stylo silage prepared with Bauhinia variegate flower

Bauhinia variegate flower (BVF) was supposed to improve silage fermentation due to its abundant active components. Thus, corn stalk and stylo were ensiled with addition of 0, 5% or 10% BVF, and then ensiling characteristics, protein fraction and bacterial community were analyzed after 60-day fermentation. The contents of butyric acid (2.9 vs not detected, 13.2 vs 3.0 g/kg DM in corn stalk and stylo silage, respectively), ammonia-N (100.2 vs 83.2, 110.8 vs 61.9 g/kg total N) and free amino acid (35.6 vs 16.5, 35.0 vs 16.4 g/kg total N) were decreased in 10% BVF treated silages. The bacterial diversity was increased, where the relative abundance of Enterobacter or Clostridium decreased and that of lactic acid producing bacteria such as Lactobacillus, Weissella or Enterococcus increased. It is suggested that BVF could be used to improve fermentation quality and nutrient preservation of high-moisture corn stalk and stylo silage.

Novel strategy to improve the colonizing ability of Irpex lacteus in non-sterile wheat straw for enhanced rumen and enzymatic digestibility

Pretreatment with white rot fungi is a promising method to enhance the digestibility of lignocelluloses; however, sterilization of feedstocks prior to inoculation is one of the costliest steps. To improve the colonizing ability of white rot fungi under non-sterile condition, Irpex lacteus, Pleurotus ostreatus, and Phanerochaete chrysosporium were inoculated in the wheat straw ensiled for 28 days and incubated for 56 days to determine the changes in microbe counts, organic acid content, chemical composition, and rumen and enzymatic digestibility. Results showed that ensiling produced abundant organic acids and suppressed most microbes in wheat straw. Significant growth of I. lacteus was observed after 3 days of incubation, and molds were only detectable at day 7 in the group. At the end of incubation, aerobic bacteria and lactic acid bacteria decreased by 18% and 38% in the wheat straw treated with I. lacteus, but molds, aerobic bacteria, and lactic acid bacteria thrived in those treated with P. ostreatus and P. chrysosporium. Even more, P. ostreatus and P. chrysosporium increased the lignin content of the ensiled wheat straw by 34% and 65%. However, I. lacteus selectively degraded lignin by 28% and improved the rumen and enzymatic digestibility by 18% and 34%. The finding indicates that ensiling prior to fermentation with I. lacteus is an effective method to control spoilage microbes and to enhance the rumen and enzymatic digestibility of wheat straw.

Dynamics of proteolysis, protease activity and bacterial community of Neolamarckia cadamba leaves silage and the effects of formic acid and Lactobacillus farciminis

To investigate the reason for well preservation of protein in Neolamarckia cadamba leaves (NCL) during ensiling, fresh NCL were ensiled with or without addition of 2.0 mL/kg formic acid (FA) or 1.0 × 10⁹CFU/kg Lactobacillus farciminis (LF), and the dynamics of protease activity and microbial community were analyzed. Nonprotein-N, free amino acid, ammonia-N, the activities of carboxypeptidase and aminopeptidase, and bacterial diversity were low during NCL ensiling. Exiguobacterium dominated in NCL silage and its relative abundance increased while Enterobacter abundance decreased during ensiling. FA lowered (P < 0.05) pH and coliform bacteria number, while LF increased (P < 0.05) lactic acid bacteria number, lactic acid content and Lactobacillus abundance at the early stage of fermentation. In summary, protein in NCL can be well preserved during ensiling likely due to its low protease and bacterial activity, and FA and LF improve the quality of NCL silage in different ways.

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.

Effects of Adding Various Silage Additives to Whole Corn Crops at Ensiling on Performance, Rumen Fermentation, and Serum Physiological Characteristics of Growing-Finishing Cattle

Simple Summary

Silage additives, such as complex lactic acid bacteria inoculants and mixed organic acid salts, are effective at improving fermentation and preservation of corn silage. However, the effects of applying these additives at ensiling on beef cattle performance require further investigation. This study showed that corn silage, inoculated with complex lactic acid bacteria, significantly improved daily dry matter intake, ruminal ammonia nitrogen, and blood urea nitrogen; and numerically enhanced the average daily gain of growing–finishing bulls. Corn crops ensilaged with mixed organic acid salts alone or together with complex inoculants had no significant effect on animal performance, although it did alter some rumen fermentation characteristics and blood parameters. Our research contributes to the future development and selection of silage additives.

Abstract

This study aimed to investigate the effect of applying various silage additives to whole corn crops at ensiling on growth performance, rumen fermentation, and blood physiology in growing–finishing bulls. Sixty Simmental × Yellow Cattle crossbred bulls were blocked by initial body weight (BW; 324.0 ± 5.4 kg) into 15 blocks. Animals in each block were randomly assigned to one of four diets formulated based on the following corn silage: control (CON), inoculated with complex lactic acid bacteria (CLB), ensilaged with mixed organic acid salts (MS), and ensilaged with CLB and MS (CLBMS). The feeding experiment lasted over 155 days, with an additional 7 days for adaptation. The results showed that bulls fed CLB-inoculated silage had greater (p < 0.05) daily dry matter intake than the other groups. The experimental treatment had no significant effect on average daily gain (p = 0.33) and feed-to-gain ratio (p = 0.13), although bulls fed CLB-inoculated silage had a larger numeric average daily gain. All additive-treated silage increased ruminal NH₃–N content (p < 0.05) and reduced the acetate-to-propionate ratio (p < 0.05) of bulls compared with the control group. Bulls fed CLB-inoculated silage had a lower ruminal pH value (p < 0.05) than that of the other groups. Compared with the control group, bulls fed CLB-inoculated silage had greater blood cholesterol, albumin, and urea nitrogen (p < 0.05). Blood physiological responses were similar in bulls fed MS-treated and control silage, whereas those in cattle fed CLBMS-treated silage were between bulls fed CLB- and MS-treated silages and more similar to the former. Taking animal performance and cost effectiveness into consideration, the application of CLB alone to whole corn crops at ensiling appears to be a better choice compared with the application of either MS alone or both of them together.

Effects of mixing Neolamarckia cadamba leaves on fermentation quality, microbial community of high moisture alfalfa and stylo silage

Neolamarckia cadamba is not only a fodder of high nutritional value, but also a source of natural antimicrobial agent. The silage quality of high moisture alfalfa and stylo with or without N. cadamba leaves (NCL) was investigated, and microbial community after ensiling was analysed. Results showed that the silage samples with NCL have lower pH (4.32 versus 4.88, 4.26 versus 4.71 in alfalfa and stylo silage, respectively), ammonia-N content (67.5 versus 146, 42.2 versus 95.1 g kg-1 total N) and higher lactic acid (13.3 versus 10.4, 17.3 versus 13.6 g kg-1 dry matter), true protein N (592 versus 287, 815 versus 589 g kg-1 total N). The addition of NCL also influenced the bacterial community distribution. The relative abundance of Clostridium and Enterobacter decreased, whereas Lactobacillus abundance increased when NCL was added. In conclusion, NCL could inhibit undesirable microorganisms in high moisture alfalfa and stylo silage. Mixing with NCL could be a feasible way to improve the quality of silage.

Caracterización organoléptica, nutricional, microbiológica y digestibilidad in vitro de ensilados con diferentes niveles de inclusión de desperdicios de alimentos

Objetivo.Caracterizar organoléptica, nutricional, microbiológica y digestibilidad in vitro de ensilados de desperdicios de alimentos recolectados en un restaurante de un centro estudios técnicos y tecnológicos con subproductos de cosecha. Metodología. Se realizó un análisis organoléptico, microbiológico, proximal de la composición, y digestibilidad in vitro de ensilajes con diferentes niveles de inclusión de desperdicios de alimentos Resultados. Se evidencia características de olor, color y textura óptimas para su palatabilidad, valores nutricionales favorables para el 30, 35 y 40% de inclusión de desperdicios, bajos promedios de proteína, pero con niveles de energía superiores a los del maíz, sorgo y soya.  La Digestibilidad in vitro de la Materia Seca (DIVMS) fue mejor para el 35% de inclusión. Así mismo las Unidades Formadoras de Colonias UFC/g para el día 21 fue 1 x101 (Escherichia coli), que se ajusta a las normas para alimentos de animales. Conclusiones. La utilización de ensilados con un 35% de inclusión de desperdicios de alimento puede ser una importante herramienta de suplementación para la alimentación porcina.

Mycotoxins occurrence and fungal populations in different types of silages for dairy cows in Spain

Silages constitute a major component of the feed ration for dairy cows, being a potential source of mycotoxins due to the possible contamination by filamentous fungi capable of producing these toxic compounds. In this study, samples of different kinds of silages collected from farms located in four regions of Spain, were analysed to evaluate the occurrence of aflatoxins (AFs) and Fusarium mycotoxins. Lactic acid bacteria and fungal populations as well as pH and water activity were also studied. Penicillium, Geotrichum and Monascus were the main fungi identified in all the silages examined. The incidence of AFs was low (10 % of positive samples). Fusarium mycotoxins were detected in 40 % of the samples and fumonisins (FBs) were the most commonly detected. Maize silage was the most heavily contaminated type of silage. Levels of mycotoxins detected in positive samples did not exceed the EU guidance values. The lack of relationship between Fusarium counts and its mycotoxin concentrations suggested that mycotoxin production possibly occurred pre-ensiling or immediately post-ensiling. Outcomes showed that mould growth and mycotoxin contamination in silages should be regularly monitored in order to minimize the exposure of dairy cows to contaminated feed.

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 diversity and fermentation quality of Moringa oleifera leaves silage prepared with lactic acid bacteria inoculants and stored at different temperatures

Four lactic acid bacteria strains (LP, LF, LL, W), isolated and selected from Moringa oleifera leaves (MOL) silage, were identified as Lactobacillus plantarum, L. farciminis, Lactococcus lactis, Weissella thailandensis, respectively. Fermentation quality and bacterial community of MOL ensiled without or with the four strains at 15 °C and 30 °C were investigated. Results showed that all the LAB strains decreased (P < 0.05) the pH and ammonia-N content of MOL silage. Silage stored at 30 °C showed higher (P < 0.05) DM loss, acetic acid and ammonia-N content, and lower LAB count than 15 °C. The environmental temperature also made a great influence on bacterial community of MOL silage. Bacterial diversity was lower and the abundance of Lactobacillus was higher in silages stored at 15 °C. In conclusion, LAB inoculants and a relatively low environmental temperature could be effective to improve the quality of MOL silage.

Fermentation quality and microbial community of alfalfa and stylo silage mixed with Moringa oleifera leaves

The silage quality of alfalfa and stylo without or with 25%, 50% Moringa oleifera leaves (MOL) was investigated, and microbial community after ensiling was analysed. Results showed that the silage samples with MOL have lower butyric acid (0.50 vs 1.20, 0.60 vs 14.5 g/kg dry matter (DM) in alfalfa and stylo silage, respectively), ammonia-N (152 vs 262, 109 vs 180 g/kg total N) content and DM loss (7.71% vs 14.6%, 6.49% vs 18.9%). The addition of MOL also influenced the bacterial community distribution. The relative abundance of Enterobacter decreased from 58.6% to 30.5%, 17.4% to 9.1% in alfalfa and stylo silage when 50% MOL was added. Clostridium decreased from 23.5% to 0.2% in stylo silage, whereas Lactobacillus abundance increased from 30.4% to 49.9%, 41.8% to 86.0% in alfalfa and stylo silage, respectively. In conclusion, mixing with MOL could be a feasible way to improve the quality of alfalfa and stylo silage.

Chemical composition, fermentative losses, and microbial counts of total mixed ration silages inoculated with different Lactobacillus species

The objective of this study was to evaluate the effects of Lactobacillus inoculants on fermentation, losses, and aerobic stability of a total mixed ration (TMR) silage. A TMR, formulated to meet the requirements of dairy cows producing 25 kg of milk/d, was applied with the following treatments prior to ensiling: 1) Control (CON), 2) Lactobacillus buchneri (105 cfu/g of fresh forage; LB), and 3) Lactobacillus plantarum (105 cfu/g of fresh forage; LP). TMR silages were ensiled for 15 and 60 d in silos equipped with an apparatus for determination of gravimetric DM, gas, and effluent losses. The experiment was performed in a complete randomized design with a 3 × 2 factorial arrangement of the treatments, with 5 replicates per treatment. Chemical changes, microbial counts, fermentation profile, and aerobic stability were measured after opening the silos. Data were submitted to ANOVA, and means were compared by Tukey and T-test and statistical significance was declared at P ≤ 0.05. After 15 d of ensiling, the inclusion of inoculant decreased NDF (P < 0.05) and butyric acid concentrations (P < 0.05) in TMR. LP had the lowest aerobic stability (P < 0.05) and the greatest loss of DM (P < 0.03). Ensiling for 60 d increased ammonia nitrogen (NH3-N), lactic acid bacteria (LAB), aerobic stability, and concentrations of lactic and acetic acid (P < 0.01) and lowered (P < 0.02) total fermentation losses compared to 15 d across all treatments. After 60 d of ensiling, LP lowered pH to the greatest extent. Treatment had no effect on concentrations of DM, CP, ADF, ash, and EE, as well as in vitro DM digestibility. In conclusion, inoculants containing LP or LB did not improve fermentation profile, did not prolong the aerobic stability, nor reduced losses. Furthermore, the 15-d ensiling period was insufficient for adequate bacterial activity.

Long-term anaerobic conservation of fruit and vegetable discards without or with moisture adjustment after aerobic preservation with sodium metabisulfite

The high moisture and soluble carbohydrates contents of fruit and vegetable discards accelerate putrefaction; thus, the immediate use of preservatives is necessary to prevent their decay and allow further use. Two series of experiments were performed to evaluate the conservation stability of fruit and vegetable discards through ensiling. Fruit and vegetable discards were not treated or treated with 6 g sodium metabisulfite/kg fruit and vegetable discards and aerobically challenged for 7 days. In Experiment 1, sodium metabisulfite-treated fruit and vegetable discards were ensiled alone as high-moisture biomass. Silage fermentation was not effective in preventing the deterioration and mold control, which resulted in the rapid depletion of sugars and dry matter loss in control silage (without sodium metabisulfite). Conversely, the low number of undesirable microorganisms resulted in the negligible loss of nutrients in the sodium metabisulfite-treated silage. In Experiment 2, sodium metabisulfite-treated fruit and vegetable discards were co-ensiled with dry by-product feeds at varying proportions to provide sodium metabisulfite loads of 1.6, 2.4, 3.2, and 4 g/kg biomass. Based on microbiological, nutrient composition, and organoleptic evaluations, the sodium metabisulfite load of 3.2 g/kg biomass provided the most desirable conservation parameters. This study provides a clean route to the safe utilization of the discards for a prolonged period, with negligible dry matter and nutrient loss.

Comparison of nitrogen transformation dynamics in non-irradiated and irradiated alfalfa and red clover during ensiling

Objective

To study the contribution of plant enzyme and microbial activities on protein degradation in silage, this study evaluated the nitrogen transformation dynamics during ensiling of non- and irradiated alfalfa (Medicago sativa L.) and red clover (Trifolium pratense L.).

Methods

Alfalfa and red clover silages were prepared and equally divided into two groups. One group was exposed to γ-irradiation at a recommended dosage (25 Gky). Therefore, four types of silages were produced: i) non-irradiated alfalfa silage; ii) irradiated alfalfa silage; iii) non-irradiated red clover silage; and iv) irradiated red clover silage. These silages were opened for fermentation quality and nitrogen components analyses after 1, 4, 8, and 30 days, respectively.

Results

The γ-irradiation successfully suppressed microbial activity, indicated by high pH and no apparent increases in fermentation end products in irradiated silages. All nitrogen components, except for peptide-N, increased throughout the ensiling process. Proteolysis less occurred in red clover silages compared with alfalfa silages, indicated by smaller (p<0.05) increment in peptide-N and free amino acid N (FAA-N) during early stage of ensiling. The γ-irradiation treatment increased (p<0.05) peptide-N and FAA-N in alfalfa silage at day 1, whereas not in red clover silage; these two nitrogen components were higher (p<0.05) between day 4 and day 30 in non-irradiated silages than the irradiated silages. The ammonia nitrogen and non-protein nitrogen were highest in non-irradiated alfalfa silage and lowest in irradiated red clover silage after ensiling.

Conclusion

The result of this study indicate that red clover and alfalfa are two forages varying in their nitrogen transformation patterns, especially during early stages of ensiling. Microbial activity plays a certain role in the proteolysis and seems little affected by the presence of polyphenol oxidase in red clover compared with alfalfaa.

Dynamics of microbial community and fermentation quality during ensiling of sterile and nonsterile alfalfa with or without Lactobacillus plantarum inoculant

To reveal the mechanism of the survival and adaption of inoculated Lactobacillus plantarum during ensiling. Alfalfa was ensiled directly (A1), after γ-ray irradiation (A0), and after inoculation of the sterile (A0L) or fresh alfalfa (A1L) with Lactobacillus plantarum. The A0L had the higher lactic acid content and lower pH than that in A1L from 3 days of ensiling. Pediococcus was the dominant microbes in A1 silage, followed by Enterococcus and Lactobacillus, while Lactobacillus in A1L outnumbered all other genera at 3 d. In A0L silage, the relative abundance of Lactobacillus increased to 99.13% at day 3. It indicated that Lactobacillus could dominated the fermentation of inoculated silages regardless of the γ-ray irradiation, although there was a short lag period for irradiated alfalfa.

Dynamics of fungal community during silage fermentation of elephant grass (Pennisetum purpureum) produced in northern Vietnam

Objective

This study aimed to gain deeper insights into the dynamic changes in spoilage fungi populations during fermentation and the influence of traditional additives on silage quality.

Methods

Elephant grass (Pennisetum purpureum) was prepared without any additive (control), and with the addition of 0.5% salt, and 0.5% salt−0.2% sugar mixture. The fungal community was then determined using a classic culturing method and high-throughput sequencing at 0, 5, 15, and 60 days after ensiling.

Results

The results showed that the fungal community of elephant grass silage varied significantly between the natural fermentation without any additive and the two additive groups. The diversity and relative abundance of spoilage molds in the control group were much higher than those in the two treatment groups (p<0.05). Three species of yeasts (Candida sp., Pichia sp., Trichosporon sp.) and four spoilage molds (Fusarium sp., Aspergillus sp., Muco sp. and Penicillin sp.) were the predominant fungi in elephant grass during natural fermentation from 0 to 60 days, which were found to be significantly decreased in salt and sugar additive groups (p<0.05). Meanwhile, the diversity and relative abundance of undesirable molds in the 0.5%-salt additive group were the lowest among all groups.

Conclusion

Adding salt and sugar, particularly 0.5% salt, is a promising effective approach to reduce the amount of undesirable fungi thus, improving the silage quality of elephant grass in northern Vietnam.

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.

Isolation, Characterization and Performance of Autochthonous Spray Dried Lactic Acid Bacteria in Maize Micro and Bucket-Silos

The aim of this study was to isolate, identify and characterize lactic acid bacteria (LAB) from spontaneously fermented maize silage, and evaluate their performance as spray-dried (SD) cultures to enhance the fermentation and the aerobic stability of maize micro-silos. Eleven strains of LAB were characterized for growth kinetics, the capability to grow in vegetable-based medium (VBM), production of organic acids and the ability to tolerate heat–stress. Three strains (Lactobacillus plantarum Ls71, Pediococcus acidilactici Ls72, and Lactobacillus buchneri Ls141) were selected and further characterized for the ability to grow as single strain or in co-culture in MRS and VMB medium, to survive at freeze and spray-drying process, for their performance as SD bacteria in micro-silos and for the aerobic stability in bucket silos. L. buchneri Ls141 showed the highest growth capability in VBM and produced the highest amount of acetic acid, while L. plantarum Ls71 produced the highest amounts of lactic acid. P. acidilactici Ls72 was the most heat-resistant strain, with a reduction of 0.2 log₁₀ CFU/mL (15 min at 55°C). The three strains satisfactorily tolerated both spray and freeze-drying. After 4 days of fermentation, all the samples reached a pH value of about 3.7–3.8. A significantly lower cell load of filamentous fungi and yeasts (< 3 log₁₀ CFU/g) and a higher concentration of total LAB (> 8.7 log₁₀ CFU/g) was observed after 30 days of fermentation. A greater amount of acetic acid, crude protein, ash and ammonia nitrogen/total nitrogen was detected in inoculated silages. A significant reduction of filamentous fungi and yeasts was also observed in inoculated bucket silos after 50 d of fermentation. The aerobic stability was significantly improved in inoculated silage since the temperature remained stable after 16 days (384 h). On the contrary, an increase of 5°C was observed in control samples after 1 day. The selected strains have the potential to be produced as SD silage inoculant as they were able to accelerate the fermentation process, to control filamentous fungi and yeasts, to improve some nutritional and chemical parameters of silage and to improve aerobic stability.

Listeriosis in fattening pigs caused by poor quality silage - a case report

Background

Listeria (L.) monocytogenes as the causative agent of listeriosis in humans and different animal species, has its reservoir in the environment. It can be found in the gut and faeces of healthy pigs, but under certain circumstances it may cause clinical disease. Fatteners are usually not known to get affected by Listeria-associated septicaemia and enteritis. This case report shows, that L. monocytogenes should be part of the list of differential diagnoses, when fattening pigs suffer from haemorrhagic diarrhoea and septicaemia.

Case presentation

Here, we report of an episode of fatal listeriosis in fattening pigs in a piglet producing farm in Lower Austria, which was combined with a fattening unit with space for 450 fatteners. The mortality rate resulted in 7.8% among fattening pigs after suffering from clinical symptoms such as anorexia, bloody diarrhoea and increased body temperature. Two fattening pigs with clinical symptoms and maize silage samples were used for further diagnostics. L. monocytogenes were isolated from serosa samples of the pigs and in the corresponding fed maize silage. One animal was positively tested for Brachyspira hyodysenteriae, which may have also been involved in the development of colitis. Immunohistochemically, L. monocytogenes could be detected in high amounts in lymphatic tissue of the gut. Molecular biological characterisation of the L. monocytogenes isolates from pigs and maize silage resulted in an identical DNA-fingerprint assigned to sequence type (ST) 21. Additionally, a high content of deoxynivalenol (3000 parts per billion) was found in maize silage. Therefore, the maize silage produced under inappropriate ensilaging conditions in a silo, was most likely the source of infection. Antimicrobial therapy with amoxicillin led to a fast cure of the remaining affected fatteners.

Conclusion

To conclude, we were able to show, that L. monocytogenes can cause clinical disease in finishing pigs, which may have been a result of immunosuppression due to high deoxynivalenol exposure. When feeding silage it is important that all ensilaging procedures occur under appropriate anaerobic conditions to guarantee suppression of listerial growth.

Electronic supplementary material

The online version of this article (10.1186/s12917-018-1687-6) contains supplementary material, which is available to authorized users.

Performic Acid Controls Better Clostridium tyrobutyricum Related Bacteria than Peracetic Acid

Clostridia are anaerobic spore-forming bacteria, which degrade carbohydrates to butyric acid, carbon dioxide, hydrogen and other compounds. These bacteria are commonly found in feces of ruminants, from where they can enter to udders and milk via manure or fodder. This study was done to find a sustainable sanitation method to control the resistant clostridial spores as they are difficult to control in the food processing industry. Clostridia spoil cheeses and other dairy products, and thereby increase the carbon footprint of products and cause economical losses in the dairy industry. The efficacy of two organic peroxides; peracetic acid (PAA) and performic acid (PFA) was tested against 30 clostridia strains isolated from cattle slurry, silage, or spoiled cheeses. PAA, at a concentration of 220 mg L−1, only eliminated 6/30 clostridia strains, whereas PFA totally eliminated 26/30 clostridia strains at a concentration of 120 mg L−1. PFA therefore seems to be a more potent disinfectant than the more commonly used PAA. PFA is an effective disinfectant against Clostridium tyrobutyricum and other resistant clostridia at 120 mg L−1 for 5–10 min contact time at room temperature.

Microbial communities and natural fermentation of corn silages prepared with farm bunker-silo in Southwest China

This study analyzed the variation of microbial communities, their achieved fermentation quality, and the association between microbial diversity and environmental factors after ensiling of 96 samples prepared with bunker-silo in Southwest China. Most of natural corn silages achieved good fermentation, e.g., low pH value (<4.2) and high levels of lactic acid (36.26-79.83 mg/g DM). Weissella species were the dominant epiphytic bacteria in raw material, while Lactobacillus and Acetobacter species were prevalent in silages. Natural Lactobacillus and Pediococcus species produced more lactic acid during ensiling, while the production of acetic acid was highly positively correlated with both Acetobacter and Bradyrhizobium species. Rainfall and humidity affected community of epiphytic bacteria on the corn material, and the temperature affected richness of bacterial species during ensiling. The results confirmed that microbial community of silages in hot and humid area is unique and climatic factors ultimately affect the fermentation quality through influencing microbial community.

A meta-analysis on the effectiveness of homofermentative and heterofermentative lactic acid bacteria for corn silage

AIMS

This meta-analysis aims to assess the effect of lactic acid bacteria (LAB) inoculation on fermentation parameters, microbiological composition and aerobic stability of corn silage.

METHODS AND RESULTS

Databases (PubMed, ScienceDirect and Scopus) were searched from 1980 to 2017. The criteria for inclusion were: randomized and controlled experiments using corn silage and published in peer-reviewed journals. The meta-analysis showed that LAB supplementation increased pH, acetate and propionate concentrations, and decreased acid detergent fibre, water-soluble carbohydrates and ammoniacal nitrogen (NH3 -N) compared to controls in the pooled raw mean difference random effect model. In addition, inoculation reduced counts of yeasts and moulds, increased LAB counts and markedly improved aerobic stability in corn silage. However, results indicated that the effect of inoculants may differ depending on the administration of homofermentative or heterofermentative LAB.

CONCLUSIONS

For the development of functional bacterial inoculants, both types of LAB should be used.

SIGNIFICANCE AND IMPACT OF THE STUDY

To our knowledge, this is the first meta-analysis to compare the application of homofermentative and heterofermentative LAB for corn silage.

Bacillus velezensis as antagonist towards Penicillium roqueforti s.l. in silage: in vitro and in vivo evaluation

AIMS

The present study was conducted to evaluate the antagonistic effect of Bacillus velezensisNRRL B-23189 towards Penicillium roqueforti s.s. and Penicillium paneum (designated together as P. roqueforti s.l.) in silage conditions.

METHODS AND RESULTS

Corn silage conditions were simulated in vitro, and the impact of B. velezensis culture supernatant or cell suspension on P. roqueforti s.l. growth and roquefortine C production was evaluated. The antagonism was promising, but growth of B. velezensis in corn silage infusion was poor. Additionally, an in vivo experiment was carried out with mini-silos containing a mixture of perennial ryegrass and white clover inoculated with P. roqueforti s.l. The applied B. velezensis cell suspension was unsuccessful in reducing P. roqueforti s.l. numbers, but did not compromise the silage acidification.

CONCLUSIONS

Although the antagonism observed in vitro was promising, the applied B. velezensis cell suspension could not live up to the expectations in vivo.

SIGNIFICANCE AND IMPACT OF THE STUDY

To our knowledge, the present study is the first one evaluating the antagonistic properties of B. velezensis towards toxigenic moulds in silage conditions, offering a good base for further research.

Paenibacillus panacisoli enhances growth of Lactobacillus spp. by producing xylooligosaccharides in corn stover ensilages

The knowledge about the association of lignocellulosic biomass-degrading microbes with lactic acid bacteria (LAB) in ensilages is still limited. Paenibacillus strains are important microbes in sustainable agriculture. Here, P. panacisoli SDMCC050309 was isolated from ensiled corn stover and used as an example to investigate the effects on LAB. This strain produced at least 7 xylanases, and two of them were purified and characterized. Temperature and pH optima were determined to be 55 °C and 8.0 for Xyn10 and 40 °C and 7.0 for Xyn11, respectively. They could degraded larch wood xylan and alkali-pretreated corn stover into xylooligosaccharides (XOS). Using the produced XOS to culture Lactobacillus brevis SDMCC050297 and L. parafarraginis SDMCC050300, both of them grew well with high level of acetic acid production. The same phenomenon was observed when co-culturing those two Lactobacillus strains with P. panacisoli SDMCC050309. Therefore, P. panacisoli enhances growth of LAB by producing XOS in corn stover ensilages.

Dissolution of particulate phosphorus in pig slurry through biological acidification: A critical step for maximum phosphorus recovery as struvite

Recycling phosphorus as struvite from pig slurry requires an acidification step to dissolve the inorganic solids containing most of the phosphorus. This study focused on the biological acidification of several pig slurries using sucrose as a model organic co-substrate. Lactic acid fermentation occurred systematically, dissolving 60-90% of TP (total phosphorus) and T-Mg (total magnesium) at pH 6 or lower. Optimal pH range for maximum P dissolution aimed at struvite recovery was 5.5-6. A simple model was developed correlating pH, sucrose and buffer capacity to optimize P dissolution and future recovery using real organic waste.

Effects of inoculants Lactobacillus brevis and Lactobacillus parafarraginis on the fermentation characteristics and microbial communities of corn stover silage

To improve silage quality of crop forages, bacterial inoculants are often employed. In this study, Lactobacillus brevis SDMCC050297 and Lactobacillus parafarraginis SDMCC050300 were used as inoculants to corn stover in lab silos for ensiling. At the initial stage of ensiling, the pH value of the inoculated silages reduced more drastically, and the inoculated silages had higher lactic acid and acetic acid contents. After 20 days of ensiling, a reduction in lactic acid content coupled with an increase in acetic acid and 1,2-propanediol contents was observed in inoculated silages. Furthermore, both the amount of lactic acid bacteria and the abundance of order Lactobacillales in inoculated silages were higher than those of controls in the whole process. Meanwhile, Lb. brevis predominated before day 20 and then the dominance was shifted to Lb. parafarraginis until the late stage of ensiling. In contrast, the epiphytic Lactococcus lactic and Lb. plantarum played major roles at the beginning of naturally fermented silages and then Lb. plantarum and Lb. brevis were the most abundant at the later stage. In conclusion, these two selected strains had capability of improving the silage quality and providing the reproducible ensiling process, thus having the potential as silage inoculants.

A novel feedstuff: ensiling of cowpea (Vigna unguiculata L.) stover and apple (Malus domestica Borkh.) mixtures. Evaluation of the nutritive value, fermentation quality and aerobic stability

BACKGROUND

Agro-industrial by-products are of low economic value as foods for human consumption but may have potential value as animal feedstuffs. This study evaluated a novel feedstuff, ensiled discarded apple (85%) and cowpea stover (15%) mixtures with two different ensiling periods (45 and 60 days), regarding the nutritive value, fermentation quality and aerobic stability.

RESULTS

Generally, no differences (P > 0.05) were observed between ensiling periods for nutritive value and fermentation characteristics. Silages were stable after ensiling, presenting high lactic acid (77.3 g kg^-1 dry matter (DM)) and acetic acid (54.7 g kg^-1 DM) and low ethanol (15.7 g kg^-1 DM) and NH₃ -N (105.6 g kg^-1 total N) concentrations. No butyric acid was detected in silages, and they were aerobically stable for up to 216 h. Lactic acid bacteria numbers were high at silo opening (7.14 log colony-forming units (CFU) g^-1 ), while Enterobacteriaceae were not detected and yeasts/moulds were low (2.44 log CFU g^-1 ). Yeast/mould and Enterobacteriaceae numbers grew considerably during 12 days of air exposure.

CONCLUSION

A mixture of low calibre discarded apples with cowpea stover can be used as animal feed after the ensiling process owing to its nutritive value and long aerobic stability. © 2017 Society of Chemical Industry.

Elephant grass silages with or without wilting, with cassava meal in silage production

SUMMARY The experiment was developed to evaluate the effects of wilting and inclusion of cassava meal level on nutritive value, fermentative characteristics and losses of elephant grass silage. The 4 x 2 factorial scheme was adopted, with four repetitions, in a completely randomized design. The factors evaluated were wilting (without and with) and cassava meal level (0; 7.5; 15 and 22.5% of natural matter, DN). PVC silos with 50 cm height and 10 cm diameter were used for silages production, which were opened after 60 days. The wilting and cassava meal addition had increasing linear effect on DM content. Silages with cassava meal showed reduction of total nitrogen, ether extract, acid detergent insoluble nitrogen, neutral detergent fiber ash and protein free, acid detergent fiber, celluloses, hemicelluloses and lignin contents and increase of organic matter content, DM in vitro digestibility and total digestible nutrients. Relative to variables inherent to silages’ fermentative characteristics, pH presented quadratic behavior. Concerning to ammonia nitrogen, it was observed quadratic and decreasing linear behavior for silages without and with wilting, respectively. Wilting and cassava meal inclusion provided smaller effluent losses.

Characterization of Feruloyl Esterases Produced by the Four Lactobacillus Species: L. amylovorus, L. acidophilus, L. farciminis and L. fermentum, Isolated from Ensiled Corn Stover

Lactic acid bacteria (LAB) play important roles in silage fermentation, which depends on the production of sufficient organic acids to inhibit the growth of undesirable microorganisms. However, LAB are not able to degrade cellulose and hemicellulose. Bacteria and fibrolytic enzymes are usually used as inoculants to improve the silage quality and digestibility. In the present study, we isolated four Lactobacillus strains (L. amylovorus CGMCC 11056, L. acidophilus CCTCC AB2010208, L. farciminis CCTCC AB2016237 and L. fermentum CCTCC AB2010204) with feruloyl esterase (FAE) activities from ensiled corn stover (CS) by a plate screening assay. The genes encoding FAEs were cloned and hetero-expressed in Escherichia coli. The optimal temperature and pH of these purified enzymes ranged from 45 to 50°C and from 7.0 to 8.0, respectively. They could hydrolyze hydroxycinnamoyl esters in a substrate-specific manner when methyl ferulate, methyl caffeate, methyl ρ-coumarate and methyl sinapinate were used as substrates. Moreover, these four FAEs were able to hydrolyze CS to release hydroxycinnamic acids. Furthermore, these strains could degrade hydroxycinnamic esters, and L. amylovorus CGMCC 11056 was the most efficient strain among these four isolates. These results provided a new target for the development of inoculants to improve silage quality and digestibility.

Biogenic amines and mycotoxins concentrations in baled silage from organic and conventional farms

ABSTRACT The aim of the current study was to investigate biogenic amines and mycotoxins concentrations in baled silage (mainly Poaceae family grasses) prepared in organic and conventional farms and to relate these parameters to fermentative parameters. The mean dry matter (DM) content was 364.10±93.31 and 424.70±95.93g/kg in the silage from organic and conventional farms respectively. The silage samples from organic farms had 17.00% higher (P≤ 0.05) tyramine (TY) than the silage from conventional farms. Conventional farm samples were characterized by 46.00% higher histamine (HIS) (P≤ 0.05), 9.80% higher putrescine (PUT) (P≤ 0.05), 17.30% higher cadaverine (CAD) (P≤ 0.05). Aflatoxins (AFL) (total) and zearalenone (ZEN), T-2/HT-2 concentrations were higher respectively 16.00% (P≤ 0.05) and 13.40% (P≤ 0.05), 1.80% (P≤ 0.05) in the silage prepared in organic farms. Deoxynivalenol (DON) concentration was higher 42.40% (P≤ 0.05) in silage from conventional farms. Volatile fatty acids (VFA), lactic acid, ethanol, pH and ammonia nitrogen showed that the silage samples from organic and conventional farms were of good quality. Our study suggests differences in biogenic amine formation or mycotoxins content in silage from organic and conventional farming, but, overall, the measured values are too low to be relevant for animal health. Furthermore, these differences might as well be due to the difference in dry matter content and plant maturity between the organic and conventional silage samples.

Bacterial and fungal core microbiomes associated with small grain silages during ensiling and aerobic spoilage

Background

Describing the microbial populations present in small grain silage and understanding their changes during ensiling is of interest for improving the nutrient value of these important forage crops. Barley, oat and triticale forages as well as an intercropped mixture of the 3 crops were harvested and ensiled in mini silos for a period of 90 days, followed by 14 days of aerobic exposure. Changes in fermentation characteristics and nutritive value were assessed in terminal silages and bacterial and fungal communities during ensiling and aerobic exposure were described using 16S and 18S rDNA sequencing, respectively.

Results

All small grain silages exhibited chemical traits that were associated with well ensiled forages, such as low pH value (4.09 ± 0.28) and high levels of lactic acid (59.8 ± 14.59 mg/g DM). The number of microbial core genome operational taxonomic units (OTUs) decreased with time of ensiling. Taxonomic bacterial community profiles were dominated by the Lactobacillales after fermentation, with a notable increase in Bacillales as a result of aerobic exposure. Diversity of the fungal core microbiome was shown to also be reduced during ensiling. Operational taxonomic units assigned to filamentous fungi were found in the core microbiome at ensiling and after aerobic exposure, whereas the Saccharomycetales were the dominate yeast population after 90 days of ensiling and aerobic exposure. Bacterial and fungal orders typically associated with silage spoilage were identified in the core microbiome after aerobic exposure.

Conclusion

Next Generation Sequencing was successfully used to describe bacterial communities and the first record of fungal communities throughout the process of ensiling and utilization. Adequately describing the microbial ecology of silages could lead to improved ensiling practices and the selection of silage inoculants that act synergistically with the natural forage microbiome.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-017-0947-0) contains supplementary material, which is available to authorized users.

Brainstem and Cranial Nerve Disorders of Ruminants

Asymmetrical signs of brainstem disease occur relatively infrequently in ruminants. The most common differential diagnoses include listeriosis, otitis media/interna, and pituitary abscess syndrome. Although these conditions produce signs of brainstem dysfunction, the diseases can usually be differentiated based on historical findings and subtle clinical differences. Basic laboratory diagnostic tests are often not specific in the definitive diagnosis but may be supportive. Advanced imaging techniques have proven to be useful in the diagnosis of otitis media/interna. Presumptive clinical diagnosis is confirmed at necropsy. Treatment involves a prolonged course of antibiotic therapy but is unrewarding in cases of pituitary abscess syndrome.

Determination of Histamine in Silages Using Nanomaghemite Core (γ-Fe₂O₃)-Titanium Dioxide Shell Nanoparticles Off-Line Coupled with Ion Exchange Chromatography

The presence of biogenic amines is a hallmark of degraded food and its products. Herein, we focused on the utilization of magnetic nanoparticles off-line coupled with ion exchange chromatography with post-column ninhydrin derivatization and Vis detection for histamine (Him) separation and detection. Primarily, we described the synthesis of magnetic nanoparticles with nanomaghemite core (γ-Fe₂O₃) functionalized with titanium dioxide and, then, applied these particles to specific isolation of Him. To obtain further insight into interactions between paramagnetic particles’ (PMP) surface and Him, a scanning electron microscope was employed. It was shown that binding of histamine causes an increase of relative current response of deprotonated PMPs, which confirmed formation of Him-PMPs clusters. The recovery of the isolation showed that titanium dioxide-based particles were able to bind and preconcentrate Him with recovery exceeding 90%. Finally, we successfully carried out the analyses of real samples obtained from silage. We can conclude that our modified particles are suitable for Him isolation, and thus may serve as the first isolation step of Him from biological samples, as it is demonstrated on alfalfa seed variety Tereza silage.