Anti-Escherichia coli O157:H7 properties of purple prairie clover and sainfoin condensed tannins

Reduction of Escherichia coli O157:H7 in Finishing Cattle Fed Corn Genetically Modified to Produce Increased Concentrations of Alpha Amylase in the Corn Kernel

Cattle are recognized as the principal reservoir for Escherichia coli O157:H7 and preharvest food safety efforts often focus on decreasing shedding of this pathogen in cattle feces. Enogen® corn (EC; Syngenta Seeds, LLC) is genetically modified to produce enhanced concentrations of α-amylase in the corn kernel endosperm. Research has demonstrated improvements in feed efficiency for cattle fed EC and research has not yet explored whether improved digestion impacts foodborne pathogen populations in cattle. Therefore, this study explored effects of finishing diets containing EC on Escherichia coli O157:H7 prevalence in cattle. A 2 × 2 factorial experiment was conducted with steers (n = 960) fed diets consisting of 2 types of silage (EC or Control) and grain (EC or Control), fed daily ad libitum. Steers were grouped into 12 blocks by incoming body weight, blocks were randomly assigned to one of four pens, and pens were randomly assigned to one diet. Cattle were sampled using rectoanal mucosal swabs in cohorts of 298-337 cattle per day, for a total of 3 sampling days (15-16 days apart). Escherichia coli O157:H7 prevalence rates ranged from not detected (0/75) to 10.0% (8/80) depending on sampling day. Tests for the silage × corn interaction, and the main effects of silage and corn, were not significant (p > 0.05); however, EC reduced the odds of Escherichia coli O157:H7 prevalence by 43% compared to the control corn diet (p = 0.07). Diets containing EC tended to decrease Escherichia coli O157:H7 prevalence in feedlot cattle; however, this reduction was not significant. Before a conclusion can be drawn about impact of EC on Escherichia coli O157:H7 in cattle, further research is necessary to (1) determine if this tendency is due to increased alpha amylase activity and (2) elucidate impact on Escherichia coli O157:H7 prevalence and concentration, as well as a possible mechanism of action.

Effects of Condensed Tannins on Bacterial and Fungal Communities during Aerobic Exposure of Sainfoin Silage

BACKGROUND

Sainfoin is a forage legume that is widely distributed around the world and is beneficial for animals owing to the characteristics of its condensed tannins (CTs), which, from certain plants, can prolong the aerobic stability of silage.

METHODS

The present study investigated whether sainfoin CTs can prolong aerobic stability by adding polyethylene glycol (PEG) to inactivate CT activity in the silage system.

RESULTS

The results showed that aerobic stability increased under the PEG treatment (p < 0.05). Ammonia nitrogen (0.71 g/kg DM vs. 0.94 g/kg DM; p < 0.05) was higher in the PEG-treated group compared with the control after 3 d of aerobic exposure. BA was detected only in the PEG-treated group upon aerobic exposure. Yeasts were more abundant in the control compared with the PEG-treated group after 7 d of aerobic exposure, after which the relative abundance of Lactobacillus was lower in the PEG-treated group (65.01% vs. 75.01% in the control; p < 0.05), while the relative abundance of Pediococcus was higher in the PEG-treated group compared with the control (10.9% vs. 4.49%, respectively; p < 0.05).The relative abundances of Apiotrichum and Aspergillus were lower in the control than in the PEG-treated group after 7 d of aerobic exposure.

CONCLUSIONS

The results suggested that sainfoin CTs decreased aerobic stability, but could inhibit certain bacteria and fungi, such as Pediococcus and Apiotrichum, and preserve the protein content during the aerobic exposure of silage.

Effect of an anti-methanogenic supplement on enteric methane emission, fermentation, and whole rumen metagenome in sheep

A study was conducted to investigate the impact of an anti-methanogenic product supplementation on enteric methane emissions, whole rumen metagenome and ruminal fermentation in sheep. Twelve adult male sheep were randomly divided into two groups of six animals each. Animals were fed ad libitum on a total mixed ration either without (CON) or with an anti-methanogenic supplement (Harit Dhara-HD). The anti-methanogenic supplement contained 22.1% tannic acid in a 3: 1 ratio of condensed and hydrolysable tannins. The supplementation of product revealed a significant reduction in daily enteric methane emission (21.9 vs. 17.2 g/d) and methane yield (23.2 vs. 18.2) without affecting the nutrient intake and digestibility. However, the propionate concentration in the HD treatment group was significantly higher than in the CON group. On the contrary, the ammonia nitrogen concentration was lower. The anti-methanogenic supplement significantly decreased the ruminal protozoa in the HD treatment group. Whole rumen metagenome analysis revealed that the core bacterial (Bacteroidetes and Firmicutes) and archaeal communities (Methanobrevibacter and Methanosarcina) were comparable between the CON and HD treatment groups. However, the supplementation of anti-methanogenic product led to a considerable reduction in the abundance of Proteobacteria, whereas the abundance of Lentisphaerae was greater. The supplementation significantly decreased the abundance of Methanocaldococcus, Methanococcoides, Methanocella, and Methanoregula methanogens. A total of 36 KO related to methanogenesis were identified in this study. The activities of formate dehydrogenase (EC 1.8.98.6) and tetrahydromethanopterin S-methyltransferase (EC 2.1.1.86) were significantly lowered by the anti-methanogenic product supplementation in sheep. In conclusion, the anti-methanogenic supplement has the potential to decrease enteric methane emission (~22%) at the recommended level (5% of DM) of supplementation. The contribution of minor methanogens vulnerable to supplementation to rumen methanogenesis is not known; hence, the culturing of these archaea should be taken on priority for determining the impact on overall rumen methanogenesis.

Condensed and Hydrolyzable Tannins for Reducing Methane and Nitrous Oxide Emissions in Dairy Manure-A Laboratory Incubation Study

The objectives of this study were to (1) examine the effects of plant condensed (CT) and hydrolyzable tannin (HT) extracts on CH4 and N2O emissions; (2) identify the reactions responsible for manure-derived GHG emissions, and (3) examine accompanying microbial community changes in fresh dairy manure. Five treatments were applied in triplicate to the freshly collected dairy manure, including 4% CT, 8% CT, 4% HT, 8% HT (V/V), and control (no tannin addition). Fresh dairy manure was placed into 710 mL glass incubation chambers. In vitro composted dairy manure samples were collected at 0, 24, 48, and 336 h after the start of incubation. Fluxes of N2O and CH4 were measured for 5-min/h for 14 d at a constant ambient incubation temperature of 39 °C. The addition of quebracho CT significantly decreased the CH4 flux rates compared to the tannin-free controls (215.9 mg/m2/h), with peaks of 75.6 and 89.6 mg/m2/h for 4 and 8% CT inclusion rates, respectively. Furthermore, CT significantly reduced cumulative CH4 emission by 68.2 and 57.3% at 4 and 8% CT addition, respectively. The HT treatments failed to affect CH4 reduction. However, both CT and HT reduced (p < 0.001) cumulative and flux rates of N2O emissions. The decrease in CH4 flux with CT was associated with a reduction in the abundance of Bacteroidetes and Proteobacteria.

Analyses on Flavonoids and Transcriptome Reveals Key MYB Gene for Proanthocyanidins Regulation in Onobrychis Viciifolia

Onobrychis viciifolia (sainfoin) is one of the most high-quality legume forages, which is rich in proanthocyanidins that is beneficial for the health and production of animals. In this study, proanthocyanidins and total flavonoids in leaves of 46 different sainfoin germplasm resources were evaluated, and it showed that soluble proanthocyanidin contents varied greatly in these sainfoin germplasm resources, but total flavonoids did not show significant difference. Transcriptome sequencing with high and low proanthocyanidins sainfoin resulted in the identification of totally 52,926 unigenes in sainfoin, and they were classed into different GOC categories. Among them, 1,608 unigenes were differentially expressed in high and low proanthocyanidins sainfoin samples, including 1,160 genes that were upregulated and 448 genes that were downregulated. Analysis on gene enrichment via KEGG annotation revealed that the differentially expressed genes were mainly enriched in the phenylpropanoid biosynthetic pathway and the secondary metabolism pathway. We also analyzed the expression levels of structural genes of the proanthocyanidin/flavonoid pathway in roots, stems, and leaves in the high proanthocyanidin sainfoin via RT-qPCR and found that these genes were differentially expressed in these tissues. Among them, the expression levels of F3'5'H and ANR were higher in leaves than in roots or stems, which is consistent with proanthocyanidins content in these tissues. Among MYB genes that were differentially expressed, the expression of OvMYBPA2 was relatively high in high proanthocyanidin sainfoin. Over-expression level of OvMYBPA2 in alfalfa hairy roots resulted in decreased anthocyanin content but increased proanthocyanidin content. Our study provided transcriptome information for further functional characterization of proanthocyanidin biosynthesis-related genes in sainfoin and candidate key MYB genes for bioengineering of proanthocyanidins in plants.

Effect of Intrinsic Tannins on the Fermentation Quality and Associated with the Bacterial and Fungal Community of Sainfoin Silage

Sainfoin (Onobrychis viciifolia) is rich in condensed tannins (CT). CT function includes inhibiting bacterial and fungi activity during the ensiling process. We used polyethylene glycol (PEG) to deactivate tannin activity to find out the effects of CT. The results show that the addition of PEG increased dry-matter loss (8.32% vs. 14.15%, on a dry-matter basis) after 60 d of ensiling, and also increased lactic acid (10.90% vs. 15.90%, on a dry-matter basis) and acetic-acid content (7.32% vs. 13.85%, on a dry-matter basis) after 30 d of ensiling. The PEG-treated group increased its Pediococcus relative abundance (0.37−3.38% vs. 7.82−23.5%,) during the ensiling process, increased its Gibellulopsis relative abundance after 3 d of ensiling (5.96% vs. 19.52%), increased its Vishniacozyma relative abundance after 3 d and 7 d of ensiling (2.36% vs. 17.02%, 3.65% vs. 17.17%), and increased its Aspergillus relative abundance after 7 d, 14 d and 60 d of ensiling (0.28% vs. 1.32%, 0.49% vs. 2.84% and 1.74% vs. 7.56%). However, the PEG-treated group decreased its Alternaria relative abundance during entire ensiling process (14.00−25.21% vs. 3.33−7.49%). These results suggest that condensed tannins inhibit lactic-acid bacteria fermentation though reducing Pediococcus activity, and inhibiting fungi activity depending on different strains.

Polyphenolic phytochemicals as natural feed additives to control bacterial pathogens in the chicken gut

Poultry provides an important protein source consumed globally by human population, and simultaneously, acts as a substantial reservoir of antibiotic resistant bacterial species such as Escherichia coli, Salmonella, Campylobacter, Clostridium perfringens. These bacterial species can include commensal strains with beneficial roles on poultry health and productivity, and pathogenic strains not only to poultry but zoonotically to man. This review paper evaluates the role of phytochemicals as possible alternatives to antibiotics and natural anti-bacterial agents to control antibiotic resistance in poultry. The focus of this paper is on the polyphenolic phytochemicals as they constitute the major group; carvacrol oil (the active ingredient of oregano), thymol oil (the main ingredient of oregano), oregano oil, and tannins oil as feed additives and their mechanism of actions that might enhance avian gut health by controlling antibiotic-resistant bacterial strains spread in poultry.

The Effect of Toothpastes Containing Natural Extracts on Bacterial Species of a Microcosm Biofilm and on Enamel Caries Development

This study investigated the effects of herbal toothpaste on bacterial counts and enamel demineralization. Thirty-six bovine enamel samples were exposed to a microcosm biofilm using human saliva and McBain saliva (0.2% sucrose) for 5 days at 37 °C and first incubated anaerobically, then aerobically–capnophilically. The following experimental toothpaste slurries (2 × 2 min/day) were applied: (1) Vochysia tucanorum (10 mg/g); (2) Myrcia bella (5 mg/g); (3) Matricaria chamomilla (80 mg/g); (4) Myrrha and propolis toothpaste (commercial); (5) fluoride (F) and triclosan (1450 ppm F), 0.3% triclosan and sorbitol (Colgate^®, positive control); (6) placebo (negative control). The pH of the medium was measured, bacteria were analyzed using quantitative polymerase chain reaction, and enamel demineralization was quantified using transverse microradiography. The total bacterial count was reduced by toothpaste containing Myrcia bella, Matricaria chamomilla, fluoride, and triclosan (commercial) compared to the placebo. As far as assessable, Myrcia bella, Matricaria chamomilla, and Myrrha and propolis (commercial) inhibited the outgrowth of S. mutans, while Lactobacillus spp. were reduced/eliminated by all toothpastes except Vochysia tucanorum. Mineral loss and lesion depth were significantly reduced by all toothpastes (total: 1423.6 ± 115.2 vol% × μm; 57.3 ± 9.8 μm) compared to the placebo (2420.0 ± 626.0 vol% × μm; 108.9 ± 21.17 μm). Herbal toothpastes were able to reduce enamel demineralization.

Biological Function of Plant Tannin and Its Application in Animal Health

Plant tannins are widely found in plants and can be divided into hydrolyzed tannins and condensed tannins. In recent years, researchers have become more and more interested in using tannin-rich plants and plant extracts in ruminant diets to improve the quality of animal products. Some research results show that plant tannins can effectively improve the quality of meat and milk, and enhance the oxidative stability of the product. In this paper, the classification and extraction sources of plant tannins are reviewed, as well as the biological functions of plant tannins in animals. The antioxidant function of plant tannins is discussed, and the influence of their structure on antioxidation is analyzed. The effects of plant tannins against pathogenic bacteria and the mechanism of action are discussed, and the relationship between antibacterial action and antioxidant action is analyzed. The inhibitory effect of plant tannins on many kinds of pathogenic viruses and their action pathways are discussed, as are the antiparasitic properties of plant tannins. The anti-inflammatory action of tannins and its mechanism are analyzed. The function of plant tannins in antidiarrheal action and its influencing factors are discussed. In addition, the effects of plant tannins as feed additives on animals and the influencing factors are reviewed in this paper to provide a reference for further research.

Characterizing Selected Sorghum Grain Varieties and Evaluating the Suitability of Their Malt Extracts for Cultivating Microbial Biomass

Microbial biomass is cultivated for different technological applications including food processing, medicine, waste management, and research. The conventional growth media used are generally expensive thus necessitating the development of more affordable alternatives. In this study, four sorghum grain varieties, SESO 1, SESO 3, Epuripur, and Eyera, and their malt extracts were characterized which is aimed at determining their suitability for growing microbial biomass. The varieties had kernel length, kernel width, kernel thickness, and thousand kernel weigh equivalent to 3.8-4.3 mm, 3.2-4.5 mm, 2.4-2.8 mm, and 12.4-20.2 g, respectively. SESO 1 and Epuripur had corneous endosperm textures whereas those of SESO 3 and Eyera were intermediate and floury, respectively. Varieties had germinative energies > 90% and total defects < 8%. SESO 3 had the highest (p < 0.05) crude protein (10.8 ± 0.3%) and dietary fiber (22.5 ± 0.4%) whereas Epuripur had the highest (p < 0.05) starch (81.6 ± 0.0%) and crude fat (2.9 ± 0.1%). There was no significant difference (p > 0.05) in the ash contents (2.1 ± 0.0%). The total sugars, free amino nitrogen, condensed tannins, and pH of the malt extracts were 106-116 g/L, 70-78 mg/L, 0.1-0.6 mg/mL, and 5.5-5.7, respectively. The composition of the sorghum malt extracts suggests their potential for use in cultivating microbial biomass.

Composition and Protein Precipitation Capacity of Condensed Tannins in Purple Prairie Clover (Dalea purpurea Vent.)

This study aimed to determine the concentration and composition of condensed tannins (CT) in different tissues of purple prairie clover (PPC; Dalea purpurea Vent.) at different maturities and to determine their protein-precipitating capacity. The compositions of CT were elucidated after thiolysis with benzyl mercaptan followed by high-performance liquid-chromatography (HPLC) and ¹H-¹³C heteronuclear single quantum coherence (HSQC) NMR spectroscopy. The results indicated that PPC flowering heads contained the highest CT concentration. Purple prairie clover CT consisted mainly of epicatechin (EC) and epigallocatechin (EGC) subunits. CT in the leaves were composed of more EC and less EGC than CT in stems and flowering heads at both the early flowering (EF) and late flowering (LF) head stages. The mean degree of polymerization was the highest for CT in stems and increased with maturity. CT isolated from PPC leaves at the early flowering head stage exhibited the greatest biological activity in terms of protein precipitation. Overall, the CT in PPC were predominantly procyanidins and the concentration and composition varied among the plant tissues and with maturity.

Impact of condensed tannin-containing legumes on ruminal fermentation, nutrition, and performance in ruminants: a review

Legume forages, such as sainfoin (Onobrychis viciifolia Scop.) and birdsfoot trefoil (Lotus corniculatus L.), can increase the forage quality and quantity of Western Canadian pastures, thus increasing producer profitability due to increased gains in grazing ruminants, while also reducing risk of bloat in legume pastures due to the presence of proanthocyanidins. Proanthocyanidins or condensed tannins (CT) are secondary plant polyphenol compounds that have been regarded as anti-nutritional due to their ability to bind protein in feeds, enzymes, and microbial cells, therefore disrupting microbial digestion and slowing ruminal protein and dry matter (DM) digestion. Research has shown that at high concentrations (>50 g·kg−1 DM), CT can disrupt microbial digestion. However, at low dietary inclusion rates (5–10 g·kg−1 DM), they reduce bloat risk, increase ruminal undegradable protein, reduce enteric methane production, and benefit anthelmintic activity. Yet, research gaps still exist regarding grazing persistence and forage yield of novel CT-containing forages and their biological activity due to their vast differences in CT stereochemistry, polymer size, and intermolecular linkages. The objectives of this review are to summarize information regarding the impact of CT on ruminal fermentation, carbohydrate and protein metabolism, and the potential to identify and select for forages that contain CT for ruminant production.

Alternatives to robenidine to control gastrointestinal disorders of weaner rabbits in the field

High mortality rates and oocyst excretion are found in weaner rabbits.

Gastrointestinal disorders have multifactorial origin.

Coccidiostats are commonly used in most rabbitries.

Improve understanding of the use of alternatives to robenidine in the form of natural supplements.

Gastrointestinal disorders due to Eimeria sp. and E. coli overgrowth cause high mortality in weaner rabbits and the interest in alternatives to coccidiostats is high. This study aimed to investigate the superiority of natural feed additives towards robenidine preserving gastrointestinal health in the field. Rabbits were divided into four groups, Control Group (CG) exclusively supplemented with robenidine, Sainfoin Group (SG) was supplemented with a combination of robenidine and sainfoin, and two additional groups were respectively supplemented with Herb-All COCC-X (garlic; conessi tree) (HG: Herbal Group) and by a combination of Herb-All COCC-X and Klinofeed (clinoptilolite) (MG: Mineral Group). Eimeria sp. (98,40%) and E. coli overgrowth (73.60%) could be confirmed as the main causes for losses. High mortality rates (SG: 30.00% - MG: 47.50%), also in the groups receiving robenidine (SG: 30.00%; CG: 45.00%), reinforced the importance of alternatives in the field. The natural additives of groups SG, HG and MG did not have a significant influence on the weight gains and the oocyst counts in the jejunum/ileum and caecum of slaughter rabbits at the end of the trial, compared to group CG. Significantly higher oocyst shedding in SG (p = 1.4E-03) and HG (p = 1.4E-05) during the trial may be explained by a higher surviving rate of diseased rabbits in those groups, fostered by beneficial effects of the additives, which should be investigated further.

Ellagitannin-Lipid Interaction by HR-MAS NMR Spectroscopy

Ellagitannins have antimicrobial activity, which might be related to their interactions with membrane lipids. We studied the interactions of 12 different ellagitannins and pentagalloylglucose with a lipid extract of Escherichia coli by high-resolution magic angle spinning NMR spectroscopy. The nuclear Overhauser effect was utilized to measure the cross relaxation rates between ellagitannin and lipid protons. The shifting of lipid signals in 1H NMR spectra of ellagitannin–lipid mixture due to ring current effect was also observed. The ellagitannins that showed interaction with lipids had clear structural similarities. All ellagitannins that had interactions with lipids had glucopyranose cores. In addition to the central polyol, the most important structural feature affecting the interaction seemed to be the structural flexibility of the ellagitannin. Even dimeric and trimeric ellagitannins could penetrate to the lipid bilayers if their structures were flexible with free galloyl and hexahydroxydiphenoyl groups.

Tannin polymerization: an overview

This review critically addresses the most relevant and innovative techniques for obtaining polymers from tannins.

Efficacy of chestnut and quebracho wood extracts to control Salmonella in poultry

AIMS

The study was aimed to evaluate the antibacterial activity and efficacy of chestnut and quebracho wood extracts against Salmonella by in vitro assays and in vivo trials.

METHODS AND RESULTS

The extracts showed inhibitory activity against Salmonella determined by the minimum inhibitory concentration method as well as on the adhesion and invasion of S. Gallinarum (SG) and S. Enteritidis (SE) in Caco-2 cells. Also, transmission electron microscopy revealed that extract-treated Salmonella showed disruption of cell walls and membranes, damage of the cytoplasm and tannin-protein aggregations. In addition, efficacy of the extracts to control SG and SE was evaluated in experimental infection trials in laying hens and broilers respectively. SE excretion was significantly reduced on days 5 (P < 0·01) and 12 (P < 0·025) only in the quebracho group. In the fowl typhoid infection model, hens that received the chestnut extract showed a significantly reduced mortality (P < 0·05).

CONCLUSIONS

Our results evidence that these alternative natural products may be a useful tool to control Salmonella in poultry.

SIGNIFICANCE AND IMPACT OF THE STUDY

Salmonella is a zoonotic pathogen usually associated with poultry production. This study provides information about the mechanism of antibacterial effects of chestnut and quebracho wood extracts to control Salmonella in poultry.

Comparative Efficacy of Selected Phytobiotics with Halquinol and Tetracycline on Gut Morphology, Ileal Digestibility, Cecal Microbiota Composition and Growth Performance in Broiler Chickens

Simple Summary

Antimicrobial growth promoters (AGPs) are banned in Europe but still used in many countries including Asia. However, their indiscriminate use resulted in antibiotic-resistant bacterial strains that possibly transfer the resistant genes to the microorganisms pertinent to human health. Hence, it is essential to find alternatives that can improve the production performance in broiler chickens. In this scenario, phytobiotics or phytogenic feed additives (PFAs) are widely investigated to evaluate their influence on improving gut health, increasing digestibility, and thereby the growth performance. The present study is a continuity of our experiments on dietary inclusion of Piper betle and Persicaria odorata leaf meal and the first of its kind to evaluate the comparative efficacy of phytobiotics (Piper betle and Persicaria odorata leaf meal), with halquinol and tetracycline in broiler chickens. The current experiment findings indicated that, in comparison with the control group, either of the dietary treatments positively modulated the gut morphology, improved ileal digestibility, maintained the intestinal population of Lactobacillus and reduced the pathogenic bacteria such as Staphylococcus aureus, Salmonella, Escherichia coli, and Clostridium spp., thus improved the growth performance in broiler chickens.

Abstract

The current experiment was designed to estimate the comparative efficacy of selected phytobiotics Persicaria odorata leaf meal (POLM) and Piper betle leaf meal (PBLM) with halquinol, and tetracycline in broiler chickens. The 150-day-old broiler chickens were randomly assigned to five dietary groups. The dietary supplementation groups were the basal diet (BD), which served as the negative control (NC), and BD + 0.2 g/kg tetracycline, which served as the positive control (PC); BD + 0.03 g/kg halquinol (HAL), BD + 8 g/kg POLM (Po8), and BD + 4 g/kg PBLM (Pb4) were the treatment groups. Growth performance, gut morphology, ileal digestibility, and cecal microbiota composition were measured. On day 21, the body weight gain (BWG) was enhanced (p < 0.05) in the broiler chickens fed on phytobiotics (Po8 and Pb4) relative to the NC group, however, on day 42 and in terms of overall growth performance, BWG was enhanced (p < 0.05 in diets (Po8, Pb4, HAL and PC) in comparison with the NC group. Conversely, feed conversion ratio (FCR) was recorded reduced (p < 0.05) in Pb4, Po8, HAL, and PC group in comparison with the NC group. Supplementation of phytobiotics (Po8 and Pb4), HAL and PC, positively improved the gut morphology compared to the NC group. Furthermore, the maximum (p < 0.05) villus height (VH) in duodenum and jejunum was observed in broilers fed on diet Pb4. Supplementation of phytobiotics, HAL and PC, improved (p < 0.05) the digestibility of dry matter (DM) (except for HAL), organic matter (OM), crude protein (CP), ether extract (EE), and ash compared to the NC group. Dietary supplementation of phytobiotics (Po8 and Pb4), HAL and PC, significantly reduced the E. coli, Salmonella, and Staphylococcus aureus (except for HAL) counts compared to the NC group. However, supplementation of Pb4 resulted in significantly decreased total anaerobic bacteria and Clostridium spp. counts compared to the NC group. In addition, supplementation of phytobiotics significantly increased the Lactobacillus count compared to HAL, PC, and NC groups. In conclusion, dietary supplementation of phytobiotics improved the gut morphology, positively modulated and maintained the dynamics of cecal microbiota with enhanced nutrient digestibility, thus, increased the growth performance. Based on current results, phytobiotics could be used as an alternative to AGPs for sustainable broiler chicken production.

Antimicrobial Activities of Ellagitannins against Clostridiales perfringens, Escherichia coli, Lactobacillus plantarum and Staphylococcus aureus

In this study, we tested the growth inhibition effect of 22 individual ellagitannins and of pentagalloylglucose on four bacterial species, i.e., Clostridiales perfringens, Escherichia coli, Lactobacillus plantarum and Staphylococcus aureus. All tested compounds showed antimicrobial effects against S. aureus, and almost all against E. coli and C. perfringens. For L. plantarum, no or very weak growth inhibition was detected. The level of inhibition was the greatest for S. aureus and the weakest for C. perfringens. For S. aureus, the molecular size or flexibility of ellagitannins did not show a clear relationship with their antimicrobial activity, even though rugosins E and D and pentagalloylglucose with four or five free galloyl groups had a stronger growth inhibition effect than the other ellagitannins with glucopyranose cores but with less free galloyl groups. Additionally, our results with S. aureus showed that the oligomeric linkage of ellagitannin might have an effect on its antimicrobial activity. For E. coli, the molecular size, but not the molecular flexibility, of ellagitannins seemed to be an important factor. For C. perfringens, both the molecular size and the flexibility of ellagitannin were important factors. In previous studies, corilagin was used as a model for ellagitannins, but our results showed that other ellagitannins are much more efficacious; therefore, the antimicrobial effects of ellagitannins could be more significant than previously thought.

The Potential Effect of Dietary Tannins on Enteric Methane Emission and Ruminant Production, as an Alternative to Antibiotic Feed Additives – A Review

Antibiotic growth promoters in livestock nutrition cause microbial resistance which produces threats to human health. Therefore, tannins have been considered as natural alternative antibiotic feed additives which possess various biological properties including antimicrobial, anti-inflammatory, antioxidant and immunomodulatory. Additionally, these plants also have antiparasitic and anti-bloat characteristics which contribute to inhibit the enteric methane emission in order to improve nutrient digestibility, milk and meat quality, fatty acids composition and ruminant production. Antibiotic growth promoters have been practiced in animals feeding to increase feed intake, growth rate, weight gain as well as reduce metabolic disorders and energy losses in the rumen. In 2006, the European Union banned the usage of antibiotic growth promoters in the feeding of livestock. This antibiotic resistance issue has increased demand to explore the natural feed additives that might be useful for animal production system. Consequently, natural forages have been categorized as potential feed additives in animal production since it improves nutritive value, protein digestibility, increase amino acid absorption and growth rate. But, some plant materials are usually rich in tannins known as anti-nutritional factors. Therefore, the application of tannin-rich plants in ruminant nutrition needs great precaution due to its possible injurious effects (dose dependent) on animal health such as metabolic disorders. Hence, there is need to give attention to the usage of tannins in ruminant nutrition as an alternative to antibiotics feed additives to investigate its effects on enteric methane emissions and ruminants production. In addition, safety and risk associated with tannins feeding have also been briefly discussed.

Technological Application of Tannin-Based Extracts

Tannins are polyphenolic compounds naturally found in vegetables. Their presence in nature has prompted their historical use in many different ways. The revision of their traditional utilization has allowed their further modification aiming for an industrial application. Sometimes these modifications have implied the addition of harmful substances such as formaldehyde, classified as a carcinogen of category B1. In other cases, these natural tannins have been replaced by synthetic compounds that threaten human and animal health and damage the environment. Therefore, currently, both academy and industry are searching for the substitution of these unsafe complexes by the increasing inclusion of tannins, natural molecules that can be obtained from several and diverse renewable resources, modified using harmless additives. To achieve promising results, cost-efficient and eco-friendly extraction methods have been designed. Once these green alternatives have been isolated, they have been successfully applied to many fields with very assorted aims of utilization such as coagulants, adhesives, floatation agents, tannings, dyes, additives, or biomolecules. Therefore, this review offers a global vision of the full process that involves the tannin’s technological application including an overview of the most relevant tannin sources, effective extraction methods, and their utilization in very diverse fields.

Advances in extraction and analysis of phenolic compounds from plant materials

Phenolic compounds, the most abundant secondary metabolites in plants, have received more and more attention in recent years because of their distinct bioactivities. This review summarizes different types of phenolic compounds and their extraction and analytical methods used in the recent reports, involving 59 phenolic compounds from 52 kinds of plants. The extraction methods include solid-liquid extraction, ultrasound-assisted extractions, microwave-assisted extractions, supercritical fluid extraction, and other methods. The analysis methods include spectrophotometry, gas chromatography, liquid chromatography, thin-layer chromatography, capillary electrophoresis, and near-infrared spectroscopy. After illustrating the specific conditions of the analytical methods, the advantages and disadvantages of each method are also summarized, pointing out their respective suitability. This review provides valuable reference for identification and/or quantification of phenolic compounds from natural products.

Potential and challenges of tannins as an alternative to in-feed antibiotics for farm animal production

Naturally occurring plant compounds including tannins, saponins and essential oils are extensively assessed as natural alternatives to in-feed antibiotics. Tannins are a group of polyphenolic compounds that are widely present in plant region and possess various biological activities including antimicrobial, anti-parasitic, anti-viral, antioxidant, anti-inflammatory, immunomodulation, etc. Therefore, tannins are the major research subject in developing natural alternative to in-feed antibiotics. Strong protein affinity is the well-recognized property of plant tannins, which has successfully been applied to ruminant nutrition to decrease protein degradation in the rumen, and thereby improve protein utilization and animal production efficiency. Incorporations of tannin-containing forage in ruminant diets to control animal pasture bloat, intestinal parasite and pathogenic bacteria load are another 3 important applications of tannins in ruminant animals. Tannins have traditionally been regarded as "anti-nutritional factor" for monogastric animals and poultry, but recent researches have revealed some of them, when applied in appropriate manner, improved intestinal microbial ecosystem, enhanced gut health and hence increased productive performance. The applicability of plant tannins as an alternative to in-feed antibiotics depends on many factors that contribute to the great variability in their observed efficacies.

Characterization of Condensed Tannins from Purple Prairie Clover (Dalea purpurea Vent.) Conserved as either Freeze-Dried Forage, Sun-Cured Hay or Silage

Conservation methods have been shown to affect forage nutrient composition and value, but little information is available about the effect of forage conservation on plant condensed tannins (CT). The objective of this study was to assess the effects of conservation method on the concentration, chemical composition and biological activity of CT. Whole-plant purple prairie clover (PPC, Dalea purpurea Vent.) was harvested at full flower and conserved as freeze-dried forage (FD), hay (HAY) or silage (SIL). Concentration of CT in conserved PPC was determined by the butanol-HCl-acetone method. Structural composition, protein-precipitation capacity and anti-bacterial activity of CT isolated from conserved forage were determined by in situ thiolytic degradation followed by HPLC-MS analysis, a protein precipitation assay using bovine serum albumin and ribulose 1,5-disphosphate carboxylase as model proteins and by an Escherichia coli (E. coli) growth test, respectively. Conservation method had no effect on concentration of total CT, but ensiling decreased (p < 0.001) extractable CT and increased (p < 0.001) protein- and fiber-bound CT. In contrast, hay-making only increased (p < 0.01) protein-bound CT. Regardless of conservation method, epigallocatechin (EGC), catechin (C) and epicatechin (EC) were the major flavan-3-ol units, and gallocatechin (GC) was absent from both terminal and extension units of PPC CT. The SIL CT had the lowest (p < 0.001) EGC, but the highest (p < 0.01) EC in the extension units. Similarly, SIL CT exhibited a lower (p < 0.001) mean degree of polymerization (mDP), but higher (p < 0.001) procyanidins (PC) than FD or HAY CT. The protein-precipitating capacity of CT in conserved PPC ranked (p < 0.001) as FD > HAY > SIL. E. coli growth n M9 medium was inhibited by 25-100 µg/mL of CT isolated from FD, HAY and SIL (p < 0.05), but preservation method had no effect on the ability of CT to inhibit bacterial growth. The results demonstrated that ensiling decreased the extractability and protein-precipitating capacity of CT by increasing the proportions of PC. Purple prairie clover conserved as hay retained more biologically active CT than if it was conserved as silage.

Condensed Tannins Affect Bacterial and Fungal Microbiomes and Mycotoxin Production during Ensiling and upon Aerobic Exposure

Purple prairie clover (PPC; Dalea purpurea Vent.) containing 84.5 g/kg dry matter (DM) of condensed tannin (CT) was ensiled without (control) or with polyethylene glycol (PEG) for 76 days, followed by 14 days of aerobic exposure. Changes in fermentation characteristics were determined, and the composition of bacterial and fungal communities were assessed using metagenomic sequencing. The addition of polyethylene glycol (PEG) that deactivated CT at ensiling increased (P < 0.05 to ∼0.001) soluble N, nonprotein N, lactic acid, total volatile fatty acids, ammonia N, deoxynivalenol (DON), and ochratoxin A (OTA) but decreased (P < 0.001) pH and water-soluble carbohydrates. The concentrations of DON and OTA increased (P < 0.001) for both silages, with the extent of increase being greater for control than for PEG-treated silage during aerobic exposure. The PEG-treated silage exhibited higher (P < 0.01 to ∼0.001) copy numbers of total bacteria, Lactobacillus, yeasts, and fungi than the control. The addition of PEG decreased (P < 0.01) bacterial diversity during both ensiling and aerobic exposure, whereas it increased (P < 0.05) fungal diversity during aerobic exposure. The addition of PEG at ensiling increased (P < 0.05) the abundances of Lactobacillus and Pediococcus species but decreased (P < 0.01) the abundances of Lactococcus and Leuconostoc species. Filamentous fungi were found in the microbiome at ensiling and after aerobic exposure, whereas Bacillus spp. were the dominate bacteria after aerobic exposure. In conclusion, CT decreased protein degradation and improved the aerobic stability of silage. These desirable outcomes likely reflect the ability of PPC CT to inhibit those microorganisms involved in lowering silage quality and in the production of mycotoxins.IMPORTANCE The present study reports the effects of condensed tannins on the complex microbial communities involved in ensiling and aerobic exposure of purple prairie clover. This study documents the ability of condensed tannins to lower mycotoxin production and the associated microbiome. Taxonomic bacterial community profiles were dominated by Lactobacillales after fermentation, with a notable increase in Bacillus spp. as a result of aerobic exposure. It is interesting to observe that condensed tannins decreased bacterial diversity during both ensiling and aerobic exposure but increased fungal diversity during aerobic exposure only. The present study indicates that the effects of condensed tannins on microbial communities lead to reduced lactic acid and total volatile fatty acid production, proteolysis, and mycotoxin concentration in the terminal silage and improved aerobic stability. Condensed tannins could be used as an additive to control unfavorable microbial development and maybe enhanced feed safety.

Fecal microbiota of lambs fed purple prairie clover (Dalea purpurea Vent.) and alfalfa (Medicago sativa)

The present study assessed the effect of purple prairie clover (PPC) and PPC condensed tannins (CT) on the fecal microbiota of lambs using high-throughput 16S rRNA gene pyrosequencing. A total of 18 individual lambs were randomly divided into three groups and fed either green chop alfalfa (Alf), a 40:60 (DM basis; Mix) mixture of Alf and PPC, or Mix supplemented with polyethylene glycol (Mix-P) for 18 days. Fecal samples were collected on days 13 through 18 using digital rectal retrieval. The DNA of fecal samples was extracted and the microbial 16S rRNA gene amplicons were sequenced using 454 pyrosequencing. Regardless of diet, the bacterial community was dominated by Firmicutes and Bacteroidetes with many sequences unclassified at the genus level. Forage type and CT had no effect on the fecal microbial composition at the phylum level or on α-diversity. Compared to the Alf diet, the Mix diet reduced the relative abundance of Akkermansia (P = 0.03) and Asteroleplasma (P = 0.05). Fecal microbial populations in Alf and Mix-P clustered separately from each other when assessed using unweighted UniFrac (P < 0.05). These results indicate that PPC CT up to 36 g/kg DM in the diet had no major effect on fecal microbial flora at the phyla level and exerted only minor effects on the genera composition of fecal microbiota in lambs.

The Occurrence, Biosynthesis, and Molecular Structure of Proanthocyanidins and Their Effects on Legume Forage Protein Precipitation, Digestion and Absorption in the Ruminant Digestive Tract

Forages grown in temperate regions, such as alfalfa (Medicago sativa L.) and white clover (Trefolium repens L.), typically have a high nutritional value when fed to ruminants. Their high protein content and degradation rate result, however, in poor utilization of protein from the forage resulting in excessive excretion of nitrogen into the environment by the animal. Proanthocyanindins (also known as condensed tannins) found in some forage legumes such as birdsfoot trefoil (Lotus corniculatus L.), bind to dietary protein and can improve protein utilization in the animal. This review will focus on (1) the occurrence of proanthocyanidins; (2) biosynthesis and structure of proanthocyanidins; (3) effects of proanthocyanidins on protein metabolism; (4) protein precipitating capacity of proanthocyanidins and their effects on true intestinal protein adsorption by ruminants; and (5) effect on animal health, animal performance and environmental emissions.

Therapeutic Potential of Temperate Forage Legumes: A Review

The discovery of bioactive molecules from botanical sources is an expanding field, preferentially oriented to plants having a tradition of use in medicine and providing high yields and availability. Temperate forage legumes are Fabaceae species that include worldwide-important crops. These plants possess therapeutic virtues that have not only been used in veterinary and folk medicine, but have also attracted the interest of official medicine. We have examined here Medicago sativa (alfalfa), Trifolium pratense and T. repens (clovers), Melilotus albus and M. officinalis (sweet clovers), Lotus corniculatus (birdsfoot trefoil), Onobrychis viciifolia (sainfoin), Lespedeza capitata (roundhead lespedeza), and Galega officinalis (goat's rue). The phytochemical complexes of these species contain secondary metabolites whose pharmacological potentials deserve investigation. Major classes of compounds include alkaloids and amines, cyanogenic glycosides, flavonoids, coumarins, condensed tannins, and saponins. Some of these phytochemicals have been related to antihypercholesterolemia, antidiabetic, antimenopause, anti-inflammatory, antiedema, anthelmintic, and kidney protective effects. Two widely prescribed drugs have been developed starting from temperate forage legumes, namely, the antithrombotic warfarin, inspired from sweet clover's coumarin, and the antidiabetic metformin, a derivative of sainfoin's guanidine. Available evidence suggests that temperate forage legumes are a potentially important resource for the extraction of active principles to be used as nutraceuticals and pharmaceuticals.

Phytochemicals for human disease: An update on plant-derived compounds antibacterial activity

In recent years, many studies have shown that phytochemicals exert their antibacterial activity through different mechanisms of action, such as damage to the bacterial membrane and suppression of virulence factors, including inhibition of the activity of enzymes and toxins, and bacterial biofilm formation. In this review, we summarise data from the available literature regarding the antibacterial effects of the main phytochemicals belonging to different chemical classes, alkaloids, sulfur-containing phytochemicals, terpenoids, and polyphenols. Some phytochemicals, besides having direct antimicrobial activity, showed an in vitro synergistic effect when tested in combination with conventional antibiotics, modifying antibiotic resistance. Review of the literature showed that phytochemicals represent a possible source of effective, cheap and safe antimicrobial agents, though much work must still be carried out, especially in in vivo conditions to ensure the selection of effective antimicrobial substances with low side and adverse effects.

Effects of conservation method on condensed tannin content, ruminal degradation, and in vitro intestinal digestion of purple prairie clover (Dalea purpurea Vent.)

In situ and in vitro experiments were conducted to evaluate the effect of forage conservation method on the chemical composition, ruminal degradation, and intestinal digestion of purple prairie clover (PPC), which was conserved as freeze-dried forage (FD), silage (SIL), or hay (Hay). In situ dry matter (DM), neutral detergent fiber (NDF), and crude protein (CP) degradabilities were determined by incubating the forages in three rumen-cannulated heifers for 0, 1, 2, 4, 8, 24, 48, and 72 h. Intestinal DM and CP digestions were estimated by incubating 12 h ruminal in situ residues in a modified three-step in vitro procedure. Ensiling decreased (P < 0.001) extractable condensed tannins (CT) but increased (P < 0.001) protein- and fiber-bound CT compared with FD and Hay. The ruminal disappearance of CP at 8 and 24 h was affected by conservation method (P < 0.001), ranked as SIL > FD > Hay. The effective degradability of DM was lower (P < 0.001) for Hay than for FD and SIL. Ensiling lowered (P < 0.001) whereas haymaking increased (P < 0.001) intestinal digestion of CP compared with the fresh PPC. There were no differences in intestinal DM digestion among the three conserved forages. The results suggest that PPC conserved as Hay may conserve the biological activity of CT via preserving extractable CT more than as SIL, thus having the potential to improve protein utilization in ruminants.

Immune-stimulating properties of 80% methanolic extract of Ludwigia octovalvis against Shiga toxin-producing E. coli O157:H7 in Balb/c mice following experimental infection

ETHNOPHARMACOLOGICAL RELEVANCE

Ludwigia octovalvis is an aquatic plant widely distributed throughout the tropical and sub-tropical regions. It is commonly consumed as a health drink and traditionally used for treating various ailments such as dysentery, diarrhea, diabetes, nephritisn and headache. No information is available on its in vivo antibacterial activity against an important foodborne pathogen, Shiga toxin producing Escherichia coli O157:H7.

MATERIALS AND METHODS

Male Balb/c mice were orally administered with the extract at doses of 200 or 400mg/kg body weight for one week before the infection with E. coli O157:H7 and continued for 14 consecutive days after infection. Serum antibody (IgA, IgG and IgM) levels were quantified at days 7 and 14 post-challenge by an ADVIA(®) 2400 Clinical Chemistry Auto Analyzer. Nitroblue tetrazolium (NBT) and Ceruloplasmin, as nonspecific immune parameters, were determined enzymatically.

RESULTS

A significant increase (p<0.05) in IgA serum level was indicated on the 7th day post-challenge with the pathogen in the experimental group received 400mg/kg of the extract in comparison with other groups. Total IgA serum levels on day 7 post-challenge in groups of PBS negative control, E. coli O157:H7 positive control, E. coli O157:H7+200mg/kg extract group and E. coli O157:H7+400mg/kg extract group were 709.4 ± 149.6, 1655.8 ± 139.7, 1728.6 ± 64.3 and 1971.4 ± 135.6 µg/ml, respectively. Serum IgG and IgM did not significantly change among different groups. The extract administered orally to infected Balb/c mice did not affect the NBT as well as ceruloplasmin levels.

CONCLUSIONS

The extract of L. octovalvis contains biologically active principles which increased systemic immune response to E. coli O157:H7 via potentiating the synthesis of IgA antibodies.

Purple Prairie Clover (Dalea purpurea Vent) Reduces Fecal Shedding of Escherichia coli in Pastured Cattle

A 3-year (2009 to 2011) grazing study was conducted to assess the effects of purple prairie clover (PPC; Dalea purpurea Vent) on fecal shedding of total Escherichia coli in cattle. Three pasture types were used in the experiment: bromegrass (Check), mixed cool season grasses with PPC (Simple), and mixed cool and warm grasses with PPC (Complex). Pastures were rotationally grazed during a summer and fall grazing period. PPC was grazed in summer at the vegetative or early flower stage and at the flower or early seed stage during the fall. Fecal samples were collected for enumeration of E. coli and chemical analyses. Forage samples were collected throughout grazing for analysis. Condensed tannins (CT) were only detected in Simple and Complex pastures that contained PPC, with higher concentrations found in the fall than in the summer. Fecal counts of E. coli in cattle grazing Simple and Complex pastures linearly decreased (P < 0.05) over summer to fall in all 3 years, an outcome not observed in cattle grazing the Check pasture. Across the three grazing seasons, fecal E. coli was lower (P < 0.05) in cattle grazing Simple and Complex pastures than in those grazing the Check pasture during the fall. During the fall, feces collected from cattle grazing the Check pasture had higher (P < 0.05) values for pH, N, NH3-N, total volatile fatty acids, and branched-chain volatile fatty acids, but a lower (P < 0.05) acetate:propionate ratio than feces collected from cattle grazing Simple or Complex pastures. In a second experiment, two strains of E. coli were cultured in M9 medium containing 25 to 200 μg/ml of PPC CT. Growth of E. coli was linearly (P < 0.01) reduced by increasing levels of PPC CT. Scanning electron micrographs showed electron-dense filamentous material associated with the outer membrane of E. coli cells exposed to CT. Incorporation of PPC into forage reduced the fecal shedding of E. coli from grazing cattle, likely due to the anti-E. coli properties of PPC CT.

Flavonoid-membrane interactions: involvement of flavonoid-metal complexes in raft signaling

Flavonoids are polyphenolic compounds produced by plants and delivered to the human body through food. Although the epidemiological analyses of large human populations did not reveal a simple correlation between flavonoid consumption and health, laboratory investigations and clinical trials clearly demonstrate the effectiveness of flavonoids in the prevention of cardiovascular, carcinogenic, neurodegenerative and immune diseases, as well as other diseases. At present, the abilities of flavonoids in the regulation of cell metabolism, gene expression, and protection against oxidative stress are well-known, although certain biophysical aspects of their functioning are not yet clear. Most flavonoids are poorly soluble in water and, similar to lipophilic compounds, have a tendency to accumulate in biological membranes, particularly in lipid rafts, where they can interact with different receptors and signal transducers and influence their functioning through modulation of the lipid-phase behavior. In this study, we discuss the enhancement in the lipophilicity and antioxidative activity of flavonoids after their complexation with transient metal cations. We hypothesize that flavonoid-metal complexes are involved in the formation of molecular assemblies due to the facilitation of membrane adhesion and fusion, protein-protein and protein-membrane binding, and other processes responsible for the regulation of cell metabolism and protection against environmental hazards.