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.

Flint corn silage management: influence of maturity stage, inoculation with Lentilactobacillus buchneri, and storage time on fermentation pattern, aerobic stability, and nutritional characteristics

Introduction

High quality corn silage depends on factors such as corn type, stage of crop development at harvest time, fermentation time, in addition to use or not of inoculants. This study aimed to investigate the impact of maturity stage, bacterial inoculation, and storage time on fermentation, aerobic stability, and nutritional characteristics of flint corn silage and their implications for corn silage management.

Methods

A flint corn hybrid was harvested very early, early, and medium (at 250, 300 and 350 g dry matter (DM)/kg as fed, respectively) and ensiled in mini-silos without (control) or with Lentilactobacillus buchneri CNCM I-4323 at 1 × 105 cfu/g for 120, 240 and 360 d to investigate how these factors interact with each other.

Results and discussion

There was only a small increase (7 g/kg starch; p = 0.003) in starch digestibility (starch-D) in the silages stored for 360 d when compared to that stored for 240 d, but with no difference for 120 d. Despite the reduced starch-D (526 vs. 694 g/kg starch; p < 0.001), silages produced from medium harvest had higher (p < 0.001) starch content (317 vs. 137 g/kg DM) and higher amount of digestible starch (169 vs. 98.5 g/kg DM; p < 0.001) compared to very early harvest. The 2-way interactions (inoculation × storage time and maturity × storage time) showed that inoculation of corn silage with L. buchneri increased (p < 0.001) the aerobic stability, and that more mature crop silage had higher aerobic stability (140 h; p = 0.036) than the others (118 and 48.5 h for those silages from very early and early harvest).

Conclusion

The storage for a longer time (>120 d) with the goal of increasing silage digestibility did not occur. Harvesting whole-crop flint corn with 300 to 350 g/kg DM is desirable to have higher DM yield and starch accumulation. Inoculation with L. buchneri is recommended to preserve the silage against aerobic deterioration. This study has shown the importance of harvesting flint corn at the right time, and the need for inoculation with L. buchneri to ensure greater yield, starch accumulation, and silage preservation, if 120 days of storage are not exceeded.

Effects of inoculating feruloyl esterase-producing Lactiplantibacillus plantarum A1 on ensiling characteristics, in vitro ruminal fermentation and microbiota of alfalfa silage

BACKGROUND

Ferulic acid esterase (FAE)-secreting Lactiplantibacillus plantarum A1 (Lp A1) is a promising silage inoculant due to the FAE's ability to alter the plant cell wall structure during ensiling, an action that is expected to improve forage digestibility. However, little is known regarding the impacts of Lp A1 on rumen microbiota. Our research assessed the influences of Lp A1 in comparison to a widely adopted commercial inoculant Lp MTD/1 on alfalfa's ensilage, in vitro rumen incubation and microbiota.

RESULTS

Samples of fresh and ensiled alfalfa treated with (either Lp A1 or Lp MTD/1) or without additives (as control; CON) and ensiled for 30, 60 and 90 d were used for fermentation quality, in vitro digestibility and batch culture study. Inoculants treated silage had lower (P < 0.001) pH, acetic acid concentration and dry matter (DM) loss, but higher (P = 0.001) lactic acid concentration than the CON during ensiling. Compared to the CON and Lp MTD/1, silage treated with Lp A1 had lower (P < 0.001) aNDF, ADF, ADL, hemicellulose, and cellulose contents and higher (P < 0.001) free ferulic acid concentration. Compared silage treated with Lp MTD/1, silage treated with Lp A1 had significantly (P < 0.01) improved ruminal gas production and digestibility, which were equivalent to those of fresh alfalfa. Real-time PCR analysis indicated that Lp A1 inoculation improved the relative abundances of rumen's total bacteria, fungi, Ruminococcus albus and Ruminococcus flavefaciens, while the relative abundance of methanogens was reduced by Lp MTD/1 compared with CON. Principal component analysis of rumen bacterial 16S rRNA gene amplicons showed a clear distinction between CON and inoculated treatments without noticeable distinction between Lp A1 and Lp MTD/1 treatments. Comparison analysis revealed differences in the relative abundance of some bacteria in different taxa between Lp A1 and Lp MTD/1 treatments. Silage treated with Lp A1 exhibited improved rumen fermentation characteristics due to the inoculant effects on the rumen microbial populations and bacterial community.

CONCLUSIONS

Our findings suggest that silage inoculation of the FAE-producing Lp A1 could be effective in improving silage quality and digestibility, and modulating the rumen fermentation to improve feed utilization.

The Effects of Irrigation, Genotype and Additives on Tef Silage Making

Tef is known as a multi-harvest crop with high production capacity and outstanding fodder quality. Hence, our overall goal is to develop tef as a new multi-harvest summer crop that can maintain high-quality feed and contribute to both field crops and the livestock industry in Israel. In this study, we aimed to evaluate the ability to preserve tef as silage. Four tef genotypes grown under well-watered (100%) and water-limited (75%) irrigation regimes were harvested at grain filling stage and ensiled with either no additives (control, CTL), or with heterofermentative inoculum (HI), molasses (MOL), and both MOL + HI. Our results showed for the first time that tef could be ensiled, although water-soluble carbohydrates (WSC) were lower than those in corn, "the perfect ensiling crop". Most of the tef silage qualitative parameters were better at water-limited irrigation. Additives HI or MOL or MOL + HI also improved silage parameters, e.g., lowered pH and ammonia nitrogen content, but increased in vitro dry matter digestibility, lactic acid and crude protein content, and lactic acid bacteria counts of tef silage. The current results imply increasing the diversity of local ruminant fodder crops, ensuring high-quality feed supply during the summer.

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

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

Probiotic effect of ferulic acid esterase-producing Lactobacillus plantarum inoculated alfalfa silage on digestion, antioxidant, and immunity status of lactating dairy goats

A feeding experiment was conducted to determine the effects of inoculating alfalfa silage with a ferulic acid esterase-producing inoculum on feed digestibility, rumen fermentation, antioxidant, and immunity status of lactating dairy goats. Twenty dairy goats were distributed into 2 experimental groups consisting of control diet (Lp MTD/1, including Lactobacillus plantarum MTD/1 inoculated silage) against diet containing silage treated with ferulic acid esterase-producing L. plantarum A1 (Lp A1). Alfalfa silage inoculated with a ferulic acid esterase-producing Lp A1 had better fermentation quality than the Lp MTD/1 inoculation. The application of Lp A1 improved silage antioxidant capacity as indicated by greater total antioxidant capacity (T-AOC), superoxide dismutase (SOD) and glutathion peroxidase (GSH-Px) activities in Lp A1 treated silage versus Lp MTD/1 treatment. Compared with Lp MTD/1 treated group, inoculation of silage with Lp A1 increased apparent total tract digestibility of dietary dry matter, organic matter and crude protein, and ruminal concentrations of total volatile fatty acids, acetate, propionate and isobutyrate as well. The results of current study also demonstrated improved antioxidant capacity and immune performance of dairy goats with Lp A1 inoculation. Feeding Lp A1-treated silage increased dairy goats' serum antioxidase activity, such as T-AOC, SOD, GSH-Px and catalase, and the serum concentration of immunoglobulin A, while decreased tumor necrosis factor α, interleukin (IL)-2 and IL-6. In addition, compared with Lp MTD/1, diet containing alfalfa silage inoculated with Lp A1 endowed dairy goats' milk with greater fat and protein contents, improved dairy goat milk quality without affecting feed efficiency.

Ferulic Acid Esterase Producing Lactobacillus johnsonii from Goat Feces as Corn Silage Inoculants

Ferulic acid esterase (FAE+)-producing lactobacilli are being studied as silage inoculants due to their potential of increasing forage fiber digestibility. In this work, three FAE+ Lactobacillus (L.) johnsonii strains were isolated from caprine feces and characterized according to their potential probiotic characteristics and as silage inoculants. Limosilactobacillus fermentum CRL1446, a human probiotic isolated from goat cheese, was also included in the experiments as a potential silage inoculant. FAE activity quantification, probiotic characterization, and growth in maize aqueous extract indicated that L. johnsonii ETC187 might have a better inoculant and probiotic aptitude. Nevertheless, results in whole-corn mini silos indicated that, although acid detergent fiber (ADF) was significantly reduced by this strain (3% compared with the uninoculated (UN) group), L. johnsonii ETC150 and CRL1446 not only induced similar ADF reduction but also reduced dry matter (DM) loss (by 7.3% and 6.5%, respectively) compared with the UN group. Additionally, CRL1446 increased in vitro DM degradability by 10%. All treatments reduced gas losses when compared with the UN group. The potential probiotic features of these strains, as well as their beneficial impact on corn fermentation shown in this study, encourage further studies as enhancers in animal production.

Variation of Microbial Community and Fermentation Quality in Corn Silage Treated with Lactic Acid Bacteria and Artemisia argyi during Aerobic Exposure

Silage, especially whole crop corn silage (WCCS), is an important part of ruminant diets, with its high moisture content and rich nutrient content, which can easily cause contamination by mold and their toxins, posing a great threat to ruminant production, food safety and human health. The objective of this study was to examine effects of lactic acid bacteria (LAB) Lactiplantibacillus (L.) plantarum subsp. plantarum ZA3 and Artemisia argyi (AA) on the fermentation characteristics, microbial community and mycotoxin of WCCS during 60 days (d) ensiling and subsequent 7 d aerobic exposure. The results showed that WCCS treated with LAB and AA both had lower pH value and ammonia nitrogen (NH₃-N) contents, and higher lactic and acetic acids concentration compared with other groups after 60 d ensiling. In addition, for microbial communities, Acetobacter and Enterobacter were inhibited in all AA group, while higher abundance of Lactobacilli was maintained; besides, Candida, Pichia and Kazachstania abundances were decreased in both 6% and 12% AA groups. The content of five kinds of mycotoxins were all significantly lower after 7 d of aerobic exposure. As for the total flavonoid (TF), which is significantly higher in all AA treated groups, it was positively correlated with Paenibacillus, Weissella and Lactobacilli, and negatively with Acetobacter, Enterobacteria, Kazachstania and Pichia.

Effects of Inoculants Producing Antifungal and Carboxylesterase Activities on Corn Silage and Its Shelf Life against Mold Contamination at Feed-Out Phase

The present study aimed to investigate effects of dual-purpose inoculants (antifungal and carboxylesterase activities) not only on corn silage quality, but also its shelf life against mold contamination at feed-out phase. Corn forage was ensiled for 252 d with different inoculants of the following: control (CON), Lactobacillus brevis 5M2 (5M), Lactobacillus buchneri 6M1 (6M), and mixture of 5M and 6M at 1:1 ratio (MIX). After ensiling, corn silage was contaminated with Fusarium graminearum. Silages applied inoculants had positive effects by increased organic acid and lactic acid bacteria, and decreased undesirable microbes. At feed-out phase, contamination of F. graminearum into corn silage had a negative effect on aerobic stability caused by increased growth of undesirable microbes. However, silages applied inoculants had positive effects by decreased undesirable microbes and extended lactic acid bacteria and aerobic stability. Generally, MIX silage presented better effects on organic acid production, rumen degradation, inhibition of undesirable microbes, and aerobic stability than 5M silage and 6M silage. The present study concluded that application of inoculants into corn silage had positive effects on fermentation characteristics and extended shelf life against mold contamination at feed-out phase. A mixed inoculant appeared to have better effects of antifungal and carboxylesterase than a single inoculant.

Fermentation of barley and wheat with lactic acid bacteria and exogenous enzyme on nutrient composition, microbial count, and fermentative characteristics

Characteristics of wheat and barley inoculated with a homo-fermentative (HO) or hetero-fermentative (HE) lactic acid bacteria (LAB) were investigated in separate 97 d studies conducted using a 3 × 2 factorial arrangement comparing inoculants (no inoculant, HO or HE) and multi-enzyme (no or yes) addition. The pH declined (P < 0.05) to below 4.5 by day 6, coinciding with peaks in lactobacilli and yeast counts. A more rapid decline (P < 0.05) in pH and lactobacilli count but higher (P < 0.05) yeast count was observed with HO relative to HE. Enzyme addition reduced pH in inoculated grains only, particularly with HE (inoculant × enzyme effect; P < 0.05). Higher dry matter losses (P < 0.05) were observed with HE, most apparent in barley. Lactate was generally highest in HO and was increased by enzyme addition. Acetate was higher (P < 0.05) in HE. Ethanol and ammonia were lowest (P < 0.05) in HO. Wheat neutral detergent fibre (NDF) was reduced by both inoculants compared with control, whereas enzyme addition reduced NDF content in both grains. In conclusion, although not marked, fermentation responses appeared greater in wheat than barley although either LAB inoculant improved grain fermentation characteristics. The multi-enzyme appeared active during fermentation.

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.

Dual-Purpose Inoculants and Their Effects on Corn Silage

This study was conducted to screen dual-purpose lactic acid bacteria (LAB) from uncontrolled farm-scale silage, and then we confirmed their effects on corn silage. The LAB were isolated from eight farm-scale corn silages, and then we screened the antifungal activity against Fusarium graminearum and the carboxylesterase activity using spectrophotometer with p-nitrophenyl octanoate as substrate and McIlvane solution as buffer. From a total of 25 isolates, 5M2 and 6M1 isolates were selected as silage inoculants because presented both activities of antifungal and carboxylesterase. According 16S rRNA gene sequencing method, 5M2 isolate had 100.0% similarity with Lactobacillus brevis, and 6M1 isolate had 99.7% similarity with L. buchneri. Corn forage was ensiled in bale silo (500 kg) for 72 d without inoculant (CON) or with mixture of selected isolates at 1:1 ratio (INO). The INO silage had higher nutrient digestibility in the rumen than CON silage. Acetate was higher and yeasts were lower in INO silage than in CON silage on the day of silo opening. In all days of aerobic exposure, yeasts were lower in INO silage than CON silage. The present study concluded that Lactobacillus brevis 5M2 and L. buchneri 6M1 confirmed antifungal and carboxylesterase activities on farm-scale corn silage.

Does glucose affect the de-esterification of methyl ferulate by Lactobacillus buchneri?

Silage, the fermented product from anaerobic storage of forage crops with high water contents (50%–70%), is normally used as animal feed but also for the production of biofuels and value‐added products. To improve the utilization of plant fibers during ensiling, previous attempts have aimed at breaking linkages between lignin and hemicellulose by use of Lactobacillus buchneri LN 4017 (ATCC PTA‐6138), a feruloyl esterase (FAE)‐producing strain, but results have been inconsistent. Normally, there are sufficient amounts of readily available substrates for bacterial growth in silage. We thus hypothesized that the inconsistent effect of L. buchneri LN 4017 on the digestibility of silage fibers is due to the catabolic repression of FAE activity by substrates present in silage (e.g., glucose). To test this hypothesis, we analyzed the effect of glucose on the de‐esterification of methyl ferulate (MF), a model substrate used for FAE activity assays. At three glucose:MF ratios (0:1, 1:1, and 13:1), the bacteria continued hydrolyzing MF with increasing glucose:MF ratios, indicating that the de‐esterification reaction was not repressed by glucose. We therefore conclude that the de‐esterification activity of L. buchneri LN 4017 is not repressed by silage substrates during ensiling.

Effects of wild or mutated inoculants on rye silage and its rumen fermentation indices

Objective

This study was conducted to confirm the effects of new inoculants producing-antifungal or esterase substances on rye silage and its rumen fermentation indices by comparing wild with mutated types.

Methods

Rye harvested at dough stage was ensiled into 3 L mini bucket silo (1 kg) for 90 d in triplicate following: distilled water at 20 μL/g (CON); Lactobacillus brevis 100D8 (AT) and its inactivation of antifungal genes (AT-m) at 1.2×10⁵ cfu/g, respectively; and Leuconostoc holzapfelii 5H4 (FD) and its inactivation of esterase genes (FD-est) at 1.0×10⁵ cfu/g, respectively. After silo opened, silage was sub-sampled for the analysis of ensiling quality and its rumen fermentation indices.

Results

Among the wild type inoculants (CON vs AT vs FD), FD inoculant had higher (p<0.05) in vitro digestibilities of dry matter and neutral detergent fiber, the total degradable fraction, and total volatile fatty acid in rumen, while AT inoculant had higher (p<0.05) lactate, acetate, and lactic acid bacteria in silage. Silage pH and the potentially degradable fraction in rumen increased (p<0.05) by inactivation of antifungal activity (AT vs AT-m), but lactate, acetate, and lactic acid bacteria of silage decreased (p<0.05). In silage, acetate increased (p< 0.05) by inactivation of esterase activity (FD vs FD-est) with decreases (p<0.05) of pH, ammonia-N, lactate, and yeast. Moreover, inactivation of esterase activity clearly decreased (p<0.05) in vitro digestibilities of dry matter and neutral detergent fiber, the total degradable fraction, and total volatile fatty acid in the rumen.

Conclusion

This study concluded that FD inoculant confirmed esterase activity on rye silage harvested at dough stage, while AT inoculant could not be confirmed with antifungal activity due to the absence of mold in all silages.

Effects of ferulic acid esterase-producing Lactobacillus fermentum and cellulase additives on the fermentation quality and microbial community of alfalfa silage

Background

Alfalfa (Medicago sativa) is an important forage material widely used for animal feed production. Ensiling is an effective method for preserving alfalfa, but it has shown some limitations in the production of high-quality alfalfa silage due to its low water soluble carbohydrates (WSC) content and high buffering capacity. Lactic acid bacteria (LAB) and cellulase are often used as silage additives to promote the ensiling process and enhance fermentation quality.

Methods

Experiments were conducted to investigate the effects of ferulic acid esterase (FAE)-producing Lactobacillus fermentum 17SD-2 (LF) and cellulase (CE) on the fermentation quality and microbial community of alfalfa silage. After 60 days of ensiling, analysis of fermentation quality and bacterial diversity in alfalfa silages were conducted using high-performance liquid chromatography and high-throughput sequencing methods.

Results

Alfalfa was ensiled with additives (LF, CE, and LF+CE) or without additives for 60 days. All additives increased lactic acid and decreased pH values and ammonia-N contents compared to control. Among all treatments, the combined addition of LF and CE showed lowest pH (4.66) and ammonia-N (NH₃-N, 0.57% DM) content, highest contents of lactic acid (LA, 10.51% DM), dry matter (DM, 22.54%) and crude protein (CP, 24.60% DM). Combined addition of LF and CE performed better in reducing neutral detergent fiber (NDF, 29.76% DM) and acid detergent fiber (ADF, 22.86% DM) contents than the addition of LF (33.71, 27.39% DM) or CE (32.07, 25.45% DM) alone. Moreover, the microbial analysis indicated that LF+CE treatments increased the abundance of desirable Lactobacillus and inhibited the growth of detrimental Enterobacter and Clostridia in alfalfa silage.

Discussion

Combined addition of FAE-producing LF and CE is more effective than treatments of LF or CE alone in improving fermentation quality and nutrition values of alfalfa silage. This is likely due to a synergistic effect of CE and FAE produced by LF on plant cell wall degradation, indicating that these additives promote each other to improve fiber degradation and silage fermentation. In conclusion, combined addition of FAE-producing LF and CE could be a feasible way to improve alfalfa silage quality.

Symposium review: Technologies for improving fiber utilization

The forage lignocellulosic complex is one of the greatest limitations to utilization of the nutrients and energy in fiber. Consequently, several technologies have been developed to increase forage fiber utilization by dairy cows. Physical or mechanical processing techniques reduce forage particle size and gut fill and thereby increase intake. Such techniques increase the surface area for microbial colonization and may increase fiber utilization. Genetic technologies such as brown midrib mutants (BMR) with less lignin have been among the most repeatable and practical strategies to increase fiber utilization. Newer BMR corn hybrids are better yielding than the early hybrids and recent brachytic dwarf BMR sorghum hybrids avoid lodging problems of early hybrids. Several alkalis have been effective at increasing fiber digestibility. Among these, ammoniation has the added benefit of increasing the nitrogen concentration of the forage. However, few of these have been widely adopted due to the cost and the caustic nature of the chemicals. Urea treatment is more benign but requires sufficient urease and moisture for efficacy. Ammonia-fiber expansion technology uses high temperature, moisture, and pressure to degrade lignocellulose to a greater extent than ammoniation alone, but it occurs in reactors and is therefore not currently usable on farms. Biological technologies for increasing fiber utilization such as application of exogenous fibrolytic enzymes, live yeasts, and yeast culture have had equivocal effects on forage fiber digestion in individual studies, but recent meta-analyses indicate that their overall effects are positive. Nonhydrolytic expansin-like proteins act in synergy with fibrolytic enzymes to increase fiber digestion beyond that achieved by the enzyme alone due to their ability to expand cellulose microfibrils allowing greater enzyme penetration of the cell wall matrix. White-rot fungi are perhaps the biological agents with the greatest potential for lignocellulose deconstruction, but they require aerobic conditions and several strains degrade easily digestible carbohydrates. Less ruminant nutrition research has been conducted on brown rot fungi that deconstruct lignocellulose by generating highly destructive hydroxyl radicals via the Fenton reaction. More research is needed to increase the repeatability, efficacy, cost effectiveness, and on-farm applicability of technologies for increasing fiber utilization.

Response of common silage corn hybrids to inoculant application: fermentation profile, carbohydrate fractions, and digestibility during ensiling

Corn silage digestibility studies have focussed on genetically distant corn types. Conversely, silage additive studies monitored fermentation differences without discussing the subject of hybrid digestibility. How ensiling phases and additives affect silage quality in commercial corn hybrids has not been properly examined yet. As corn silage quality is a result of combined silage fermentation and digestibility characteristics, the aim of the study was to examine fermentation and digestibility responses to inoculant application in whole-plant corn silage of commercial hybrids intended for silage production in several time points during ensiling. Three corn hybrids grown under identical conditions in a split-plot field test were ensiled without inoculant application and with inoculant containing lactic acid bacteria and carbohydrate-degrading enzymes. Silages were sampled before ensiling, at the peak of the fermentation phase and during the stable phase. The fermentation profile, carbohydrate fraction, ruminal in vitro true dry matter digestibility, ruminal in vitro starch digestibility, and ruminal in vitro neutral detergent fibre digestibility were monitored. Although adding inoculant to silage improved its lactic acid production and decrease in pH, it did not affect its starch and fibre contents or their digestibility. Digestibility improved as ensiling continued, with the highest in vitro neutral detergent fibre digestibility and in vitro true dry matter digestibility values observed in the stable phase. Corn hybrids in this study differed in main fermentation characteristics, carbohydrate contents, and digestibility. These results suggest that even for commercial corn hybrids, the hybrid type is more important than inoculant for optimising silage characteristics and digestibility.

Temperature and microbial changes of corn silage during aerobic exposure

Objective

This study was conducted to estimate the temperature and microbial changes of corn silages during aerobic exposure.

Methods

Kwangpyeongok (KW) and Pioneer 1543 (PI) corn hybrids were harvested at 29.7% of dry matter and chopped to 3 to 5 cm lengths. Homo (Lactobacillus plantarum; LP) or hetero (Lactobacillus buchneri; LB) fermentative inoculants at 1.2×10⁵ colony forming unit/g of fresh forage was applied to the chopped corn forage which was then ensiled in quadruplicate with a 2×2 (hybrid×inoculant) treatment arrangement for 100 days. After the silo was opened, silage was sub-sampled for analysis of chemical compositions, in vitro digestibility, and fermentation indices. The fresh silage was continued to determine aerobic exposure qualities by recorded temperature and microbial changes.

Results

The KW silages had higher (p<0.01) in vitro digestibilities of dry matter and neutral detergent fiber than those of PI silages. Silages applied with LB had higher (p<0.001) acetate concentration, but lower (p<0.01) lactate concentration and lactate to acetate ratio than those of LP silages. The interaction effect among hybrid and inoculant was detected in acetate production (p = 0.008), aerobic stability (p = 0.006), and lactic acid bacteria count (p = 0.048). The yeast was lower (p = 0.018) in LB silages than that in LP silages. During the aerobic exposure, PI silages showed higher (p<0.05) temperature and mold than KW silages, while LP silages had higher (p<0.05) lactic acid bacteria and yeast than LB silages.

Conclusion

The results indicated that the changes of silage temperature during aerobic exposure seems mainly affected by mold growth, while applied LB only enhanced aerobic stability of PI silages.

Impact of adding Saccharomyces strains on fermentation, aerobic stability, nutritive value, and select lactobacilli populations in corn silage

Bacterial inoculants can improve the conservation and nutritional quality of silages. Inclusion of the yeast Saccharomyces in the diet of dairy cattle has also been reported to be beneficial. The present study assessed the ability of silage to be used as a means of delivering Saccharomyces strains to ruminants. Two strains of Saccharomyces cerevisiae (strain 1 and 3)and 1 strain of Saccharomyces paradoxus (strain 2) were inoculated (10(3) cfu/g) individually onto corn forage that was ensiled in mini silos for 90 d. Fermentation characteristics, aerobic stability, and nutritive value of silages were determined and real-time quantitative PCR (RT-qPCR) was used to quantify S. cerevisiae, S.paradoxus, total Saccharomyces, fungal, and bacterial populations. Fermentation characteristics of silage inoculated with S1 were similar to control silage. Although strain 3 inoculation increased ash and decreased OM contents of silage (P = 0.017), no differences were observed in nutrient composition or fermentation profiles after 90 d of ensiling. Inoculation with Saccharomyces had no detrimental effect on the aerobic stability of silage. In vitro DM disappearance, gas production, and microbial protein synthesis were not affected by yeast inoculation.Saccharomyces strain 1 was quantified throughout ensiling, whereas strain 2 was detected only immediately after inoculation. Saccharomyces cerevisiae strain 3 was quantified until d 7 and detectable 90 d after ensiling. All inoculants were detected and quantified during aerobic exposure. Inoculation with Saccharomyces did not alter lactobacilli populations. Saccharomycetales were detected by RT-qPCR throughout ensiling in all silages. Both S. cerevisiae and S. paradoxus populations increased during aerobic exposure, demonstrating that the density of these yeast strains would increase between the time that silage was removed from storage and the time it was fed.

Effect of a dual-purpose inoculant on the quality and nutrient losses from corn silage produced in farm-scale silos

This project aimed to determine effects of applying an inoculant containing homofermentative and heterofermentative bacteria on the fermentation, nutritive value, aerobic stability, and nutrient losses from corn silage produced in farm-scale silos. Corn forage was harvested at 34% dry matter (DM) and treated without (control) or with 5 × 10⁵ cfu/g of Lactobacillus buchneri and Pediococcus pentosaceus. The inoculant was sprayed on alternate 8-row-wide swaths of forage, and the untreated and inoculated forages were alternately packed into 3.6-m-wide bag silos. Forty-five tonnes of corn forage were packed into each of 4 replicate bags per treatment and ensiled for 166 d. Silage removed from the bags (500 kg/d) was separated into good and spoiled (visibly moldy or darker) silage portions, and weighed for 35 d. Weekly composites were analyzed for chemical composition, aerobic stability, and fungal counts. Aerobic stability was measured using data loggers that recorded sample and ambient temperature every 30 min for 7 d. Inoculation did not affect the chemical composition of the spoiled or good silage but decreased the quantity (5.7 vs. 12.9 kg/d) and percentage (3.4 vs. 7.8) of spoiled silage in the bags by over 50%. Losses of crude protein (0.28 vs. 0.92 kg/d), gross energy (6.0 × 10⁴ vs. 1.8 × 10⁵ kJ/d), and neutral detergent fiber (1.34 vs. 4.12 kg/d) in spoiled silage were less in inoculated versus control silages. Inoculated silages had lower pH (3.91 vs. 3.99), lactate concentration (7.63 vs. 7.86%), lactate:acetate ratio (1.58 vs. 2.53%), and a greater acetate (5.11 vs. 3.56%) concentration than the control silage. Inoculated silages tended to have fewer yeasts (2.59 vs. 4.62 log cfu/g) than control silages, but aerobic stability was not different across treatments (14.7 vs. 9.5 h). Applying the inoculant made the fermentation more heterolactic, inhibited the growth of yeasts, and substantially reduced the amount of spoilage and the associated energy and nutrient losses.

Use of thermal imaging and the in situ technique to assess the impact of an inoculant with feruloyl esterase activity on the aerobic stability and digestibility of barley silage

Addah, W., Baah, J., Okine, E. K. and McAllister, T. A. 2012. Use of thermal imaging and the in situ technique to assess the impact of an inoculant with feruloyl esterase activity on the aerobic stability and digestibility of barley silage. Can. J. Anim. Sci. 92: 381–394. Feruloyl esters limit the digestibility of forages, a constraint that may be overcome if additives with feruloyl esterase (FE) activity are applied to forage. This study determined if a FE-producing strain of Lactobacillus buchneri LN4017 in combination with Lactobacillus plantarum LP7109 and Lactobacillus casei LC3200 improves fermentation, aerobic stability and in situ fibre disappearance of whole-crop barley silage. Barley forage (350 g kg−1 DM) was either uninoculated (UN) or inoculated (1.3×105 CFU g−1 fresh forage; IN) and ensiled in Ag-Bag® silos. Bags were opened after 90 d of ensiling. Samples were collected on day 95, 123 and 175 for determination of fermentation characteristics. Surface temperature of the face of each bag was measured over 3 d using a thermal infrared camera. Ruminal in situ DM and NDF disappearance (aNDFD) of silage and rumen fermentation patterns were measured using three ruminally cannulated heifers. The L. buchneri-treated silage possessed a higher acetic acid concentration than UN (48.8 vs.18.4 g kg−1 DM). The temperature at the face of IN was lower than UN immediately upon exposure and after 3 d of aerobic exposure. Inoculation increased (P=0.01) 24-h and 48-h aNDFD with a trend towards a glucogenic pattern of ruminal fermentation in heifer compared with UN silage. There was evidence that the FE-producing inoculant improved aerobic stability and aNDFD of whole-crop barley silage.

Effect of applying bacterial inoculants containing different types of bacteria to corn silage on the performance of dairy cattle

This study examined the effect of applying different bacterial inoculants to corn silage at the time of ensiling on the performance of lactating dairy cows. Corn plants were harvested at 35% dry matter (DM), chopped, and ensiled in 2.4-m-wide bags after application of (1) no inoculant (CON); (2) Biotal Plus II (B2) containing Pediococcus pentosaceus and Propionibacteria freudenreichii; (3) Buchneri 40788 (BUC) containing Lactobacillus buchneri; or (4) Buchneri 500 (B500) containing Pediococcus pentosaceus and L. buchneri. All inoculants were supplied by Lallemand Animal Nutrition (Milwaukee, WI). Each of the 4 silages was included in separate total mixed rations consisting of 44% corn silage, 50% concentrate, and 6% alfalfa hay (DM basis). Fifty-two lactating Holstein cows were stratified according to milk production and parity and randomly assigned at 22 d in milk to the 4 dietary treatments. Cows were fed for ad libitum consumption and milked twice daily for 49 d. Dietary treatment did not affect intakes (kg/d) of DM (20.0), crude protein (CP; 3.7), neutral detergent fiber (NDF; 5.7), or acid detergent fiber (ADF; 3.6), or digestibility (%) of DM (73.9) or CP (72.4). However, NDF digestibility was lower in cows fed B2 compared with those fed other diets (45.3 vs. 53.0%). Consequently, cows fed B2 had lower digestible NDF intake (kg/d) than those fed other diets (2.5 vs. 3.0 kg/d). Dietary treatment did not affect milk yield (32.3 kg/d), efficiency of milk production (1.61), concentrations of milk fat (3.18%) and protein (2.79%), or yields of milk fat (1.03 kg/d) and protein (1.26 kg/d). Inoculant application to corn silage did not affect milk yield or feed intake of cows.

Review: The use of direct fed microbials to mitigate pathogens and enhance production in cattle

McAllister, T. A., Beauchemin, K. A., Alazzeh, A. Y., Baah, J., Teather, R. M. and Stanford, K. 2011. Review: The use of direct fed microbials to mitigate pathogens and enhance production in cattle. Can. J. Anim. Sci. 91: 193–211. Direct-fed microbials (DFM) have been employed in ruminant production for over 30 yr. Originally, DFM were used primarily in young ruminants to accelerate establishment of the intestinal microflora involved in feed digestion and to promote gut health. Further advancements led to more sophisticated mixtures of DFM that are targeted at improving fiber digestion and preventing ruminal acidosis in mature cattle. Through these outcomes on fiber digestion/rumen health, second-generation DFM have also resulted in improvements in milk yield, growth and feed efficiency of cattle, but results have been inconsistent. More recently, there has been an emphasis on the development of DFM that exhibit activity in cattle against potentially zoonotic pathogens such as Escherichia coli O157:H7, Salmonella spp. and Staphylococcus aureus. Regulatory requirements have limited the microbial species within DFM products to organisms that are generally recognized as safe, such as lactic acid-producing bacteria (e.g., Lactobacillus and Enterococcus spp.), fungi (e.g., Aspergillus oryzae), or yeast (e.g., Saccharomyces cerevisiae). Direct-fed microbials of rumen origin, involving lactate-utilizing species (e.g., Megasphaera elsdenii, Selenomonas ruminantium, Propionibacterium spp.) and plant cell wall-degrading isolates of Butyrivibrio fibrisolvens have also been explored, but have not been commercially used. Development of DFM that are efficacious over a wide range of ruminant production systems remains challenging because[0] comprehensive knowledge of microbial ecology is lacking. Few studies have employed molecular techniques to study in detail the interaction of DFM with native microbial communities or the ruminant host. Advancements in the metagenomics of microbial communities and the genomics of microbial–host interactions may enable DFM to be formulated to improve production and promote health, responses that are presently often achieved through the use of antimicrobials in cattle.

Effect of applying inoculants with heterolactic or homolactic and heterolactic bacteria on the fermentation and quality of corn silage

This study examined the effect of applying different bacterial inoculants on the fermentation and quality of corn silage. Corn plants were harvested at 35% DM, chopped, and ensiled in 20-L mini silos after application of (1) deionized water (CON) or inoculants containing (2) 1 × 10(5) cfu/g of Pediococcus pentosaceus 12455 and Propionibacteria freudenreichii (B2); (3) 4 × 10(5) cfu/g of Lactobacillus buchneri 40788 (BUC); or (4) 1 × 10(5) cfu/g of Pediococcus pentosaceus 12455 and 4 × 10(5) cfu/g of L. buchneri 40788 (B500). Four replicates of each treatment were weighed into polyethylene bags within 20-L mini silos. Silos were stored for 575 d at ambient temperature (25°C) in a covered barn. After silos were opened, aerobic stability, chemical composition, and yeast and mold counts were determined. The DNA in treated and untreated silages was extracted using lysozyme/sodium dodecyl sulfate lysis and phenol/chloroform and used as a template for a conventional PCR with primers designed on the 16S rRNA gene to detect the presence of L. buchneri in all silage samples. Acetic acid concentration was greater in B2 silages versus others (6.46 vs. 4.23% DM). Silages treated with BUC and B500 had lower pH and propionic acid concentration and greater lactic acid concentration than others. The B500 silage had the greatest lactic:acetic acid ratio (1.54 vs. 0.41), and only treatment with BUC reduced DM losses (5.0 vs. 14.3%). Yeast and mold counts were less than the threshold (10(5)) typically associated with silage spoilage and did not differ among treatments. Consequently, all silages were very stable (>250 h). Aerobic stability was not improved by any inoculant but was lower in B500 silages versus others (276 vs. 386 h). The conventional PCR confirmed the presence of similar populations of L. buchneri in all silages. This may have contributed to the prolonged aerobic stability of all silages.