Bacterial Lactonases ZenA with Noncanonical Structural Features Hydrolyze the Mycotoxin Zearalenone

Zearalenone (ZEN) is a mycoestrogenic polyketide produced by Fusarium graminearum and other phytopathogenic members of the genus Fusarium. Contamination of cereals with ZEN is frequent, and hydrolytic detoxification with fungal lactonases has been explored. Here, we report the isolation of a bacterial strain, Rhodococcus erythropolis PFA D8-1, with ZEN hydrolyzing activity, cloning of the gene encoding α/β hydrolase ZenA encoded on the linear megaplasmid pSFRL1, and biochemical characterization of nine homologues. Furthermore, we report site-directed mutagenesis as well as structural analysis of the dimeric ZenARe of R. erythropolis and the more thermostable, tetrameric ZenAScfl of Streptomyces coelicoflavus with and without bound ligands. The X-ray crystal structures not only revealed canonical features of α/β hydrolases with a cap domain including a Ser-His-Asp catalytic triad but also unusual features including an uncommon oxyanion hole motif and a peripheral, short antiparallel β-sheet involved in tetramer interactions. Presteady-state kinetic analyses for ZenARe and ZenAScfl identified balanced rate-limiting steps of the reaction cycle, which can change depending on temperature. Some new bacterial ZEN lactonases have lower KM and higher kcat than the known fungal ZEN lactonases and may lend themselves to enzyme technology development for the degradation of ZEN in feed or food.

Mycotoxin Occurrence in Feeds and Raw Materials in China: A Five-Year Investigation

Mycotoxins are ubiquitously present in feeds and raw materials and can exert toxicity on animals and humans. Therefore, mycotoxin occurrence should be monitored. We report here a multi-mycotoxin survey of feed samples in China from 2017 to 2021. Concentrations of aflatoxins, trichothecenes type B, fumonisins, and zearalenone were determined in a total of 9392 samples collected throughout China. Regional differences and year-to-year variation of mycotoxin occurrence were also assessed in new-season corn. Generally, Fusarium mycotoxins were prevalent, while mycotoxin contamination in each feed commodity showed a distinct pattern, e.g., wheat and bran were typically affected by trichothecenes type B, peanut meals were highly susceptible to aflatoxins, and finished feeds exhibited a comparatively high prevalence of all mycotoxins. In new-season corn, trichothecenes type B and fumonisins were most prevalent, with positive rates of 84.04% and 87.16%, respectively. Regions exhibited different patterns of mycotoxin occurrence. The Anhui and Jiangsu provinces of East China exhibited a high prevalence and concentrations of aflatoxins with a positive rate and a positive average of 82.61% and 103.08 μg/kg, respectively. Central China obtained high fumonisins levels of 4707.84 μg/kg. Trichothecenes type B and zearalenone occurred more frequently in temperate regions of Northeast China, and their positive rates reached 94.99% and 55.67%, respectively. In these regions, mycotoxin concentrations in new-season corn exhibited pronounced year-to-year variations and this could be due to the unusual changes of rainfall or temperature during sensitive periods of corn growing. A large fraction of new-season corn samples contained multiple mycotoxins with two to three classes (75.42%), and the most frequently observed co-contaminants were the combination of trichothecenes type B and fumonisins (73.52%). Trichothecenes type B and zearalenone concentrations were highly positively correlated with a coefficient of 0.775. In conclusion, mycotoxins contamination and co-contamination of feeds are common. Mycotoxin contamination in new-season corn exhibited regional patterns and year-to-year variations, with climate and weather conditions as determinant factors.

Dose-dependent impact of enrofloxacin on broiler chicken gut resistome is mitigated by synbiotic application

Fluoroquinolone agents are considered critical for human medicine by the World Health Organization (WHO). However, they are often used for the treatment of avian colibacillosis in poultry production, creating considerable concern regarding the potential spread of fluoroquinolone resistance genes from commensals to pathogens. Therefore, there is a need to understand the impact of fluoroquinolone application on the reservoir of ARGs in poultry gut and devise means to circumvent potential resistome expansion. Building upon a recent dose optimization effort, we used shotgun metagenomics to investigate the time-course change in the cecal microbiome and resistome of broiler chickens receiving an optimized dosage [12.5 mg/kg body weight (bw)/day], with or without synbiotic supplementation (PoultryStar^®, BIOMIN GmbH), and a high dosage of enrofloxacin (50 mg/kg bw/day). Compared to the high dose treatment, the low (optimized) dose of enrofloxacin caused the most significant perturbations in the cecal microbiota and resistome of the broiler chickens, demonstrated by a lower cecal microbiota diversity while substantially increasing the antibiotic resistance genes (ARGs) resistome diversity. Withdrawal of antibiotics resulted in a pronounced reduction in ARG diversity. Chickens receiving the synbiotic treatment had the lowest diversity and number of enriched ARGs, suggesting an alleviating impact on the burden of the gut resistome. Some Proteobacteria were significantly increased in the cecal metagenome of chickens receiving enrofloxacin and showed a positive association with increased ARG burden. Differential abundance (DA) analysis revealed a significant increase in the abundance of ARGs encoding resistance to macrolides-lincosamides-streptogramins (MLS), aminoglycosides, and tetracyclines over the period of enrofloxacin application, with the optimized dosage application resulting in a twofold higher number of affected ARG compared to high dosage application. Our results provide novel insights into the dose-dependent effects of clinically important enrofloxacin application in shaping the broiler gut resistome, which was mitigated by a synbiotic application. The contribution to ameliorating the adverse effects of antimicrobial agents, that is, lowering the spread of antimicrobial resistance genes, on the poultry and potentially other livestock gastrointestinal microbiomes and resistomes merits further study.

Exploring With Transcriptomic Approaches the Underlying Mechanisms of an Essential Oil-Based Phytogenic in the Small Intestine and Liver of Pigs

Phytogenics are plant-based feed additives utilized in animal nutrition to support animal growth and health. Worldwide restrictions and bans on the use of antibiotic growth promoters resulted in an increased demand for in-feed alternatives including phytogenics. However, several challenges remain for technology readiness in animal industry, especially regarding the standardization of the ingredients as well as our knowledge on the cellular mechanisms underlying their biological effects. In the present study, 32 weaned piglets were allocated for 28 days to four experimental diets, a control diet, a phytogenic feed additive (PFA) diet, or the same two diets but with the addition of oxidized oil (OO) at 10%. The last two diets aimed at evaluating the antioxidant properties of PFA. At the end of the trial, the ileum and the liver of the pigs were sampled, and RNA were isolated for profiling their transcriptome via RNA sequencing (RNA-Seq). In the ileum, the gene set enrichment analysis showed that the activity of several immune pathways (NF-kB, interferon α/β, antimicrobial peptide, and collagen pathways) was reduced in piglets fed PFA compared to the control piglets. As expected, the addition of OO induced strong effects on the liver transcriptome and most likely accounted for the significant growth impairment. The likelihood ratio test across the four diets revealed a global response driven by the oxidative stress challenge with hundreds of genes associated with fatty acid β-oxidation and peroxisome in the liver. The expression levels of those genes in the piglets fed OO+PFA were much less affected by the challenge. Collectively, the effects seen at day 28 suggest that substances in the PFA formulation provide anti-inflammatory and antioxidant properties. The use of RNA-Seq in animal nutrition allows exploring and deciphering novel mechanisms of natural growth promoters.

The impact of management practices to prevent and control mycotoxins in the European food supply chain: MyToolBox project results

The presence of mycotoxins in cereals has led to large economic losses in Europe. In the course of the European project MyToolBox, prevention and control measures to reduce mycotoxin contamination in cereals were developed. This study aimed to estimate the impact of these prevention and control measures on both the reduction in crop losses and the increased volume of crops suitable for food and/or feed. It focused on the following measures: the use of fungicides during wheat cultivation, the use of resistant maize cultivars and/or biocontrol during maize cultivation, the use of real time sensors in storage silos, the use of innovative milling strategies during the pasta making process, and the employment of degrading enzymes during the process of bioethanol and Dried Distillers Grains with Solubles (DDGS) production. The impact assessment was based on the annual volume of cereals produced, the annual levels of mycotoxin contamination, and experimental data on the prevention and control measures collected in the course of the MyToolBox project. Results are expressed in terms of reduced volumes of cereals lost, or as additional volumes of cereals available for food meeting the current European legal limits. Results showed that a reduction in crop losses as well as an increase in the volume of crops suitable as food and/or feed is feasible with each proposed prevention or control measure along the supply chain. The impact was the largest in areas and in years with the highest mycotoxin contamination levels but would have less impact in years with low mycotoxin levels. In further research, the impact assessment may be validated using future data from more years and European sites. Decision makers in the food and feed supply chain can use this impact assessment to decide on the relevant prevention and control strategies to apply.

Research Note: Snapshot of the transcriptome via RNA sequencing in the ileum of broiler chickens fed subtherapeutic concentrations of avilamycin

Antibiotics have played a critical role in sustaining and improving livestock production in the past decades, but the emergence of antimicrobial resistance has led several countries to ban or limit their use. Since then, in-feed alternatives have gained a lot of attention but the development of efficacious alternatives implies a better understanding of the mode of action of antibiotic growth promoters (AGP) when administered at subtherapeutic concentrations. In the present study, 120 broiler chickens per group (8 pens/group) were fed for 35 d with either basal feed (control group) or feed supplemented with avilamycin (AGP group; 10 g/1,000 kg of feed). At the end of the trial, the ileum from the small intestine of 5 birds per group was sampled, and RNA were isolated for profiling their transcriptome via RNA sequencing (RNA-Seq). As expected, the growth of chickens in the AGP group was significantly higher than in the control group. Overall, 66 differentially expressed genes (false discovery rate ≤ 0.05 and fold change ≥ 2 or ≤ −2) were found in the ileum of chickens fed avilamycin in comparison with the control group. The functional analysis showed reduced activity of genes related to signaling by interleukins, with IL-22, SOCS3, and certain antimicrobial peptides found multiple times in these pathways in the AGP group at day 35. In addition, higher activity was predicted in a module of genes related to lipid metabolism and transport in the avilamycin group. The use of RNA-Seq allowed a snapshot of the whole transcriptome at day 35 and aimed at delivering additional data on the host-centric hypothesis regarding the mode of action of AGP (i.e. immunomodulation, reduction of the immunological stress).

The MyToolbox EU-China Partnership-Progress and Future Directions in Mycotoxin Research and Management

Affordable and practical tools for farmers and food processors along the chain are required to efficiently reduce the risk of mycotoxin contamination of crops, feeds and foods. Developing new tools and enhancing existing ones was the mission of MyToolBox-a four-year EU-project that included important Chinese partners and joint research efforts. To identify future directions in mycotoxin research and management in China and their role in China-EU relations, a unique stakeholder workshop including group discussions was organized in Beijing. Six related topics: biocontrol, forecasting, sampling and analysis, silo management, detoxification, and the development of safe use options for contaminated materials were covered. The discussions clearly identified a critical need for smart, integrated strategies to address mycotoxin issues to attain safer food and feed, and to minimize losses and export rejections. Managing data on when, where and the size of mycotoxin contamination events and identifying the institution(s) to manage them are complex issues in China. Studies of microbes and novel, genetically-altered enzymes to limit pre-harvest contamination and to manage post-harvest product detoxification and alternate uses of contaminated materials are in the early stages in China. Further efforts are needed to increase the visibility of mycotoxin problems beyond the scientific and research communities.

An In Silico Target Fishing Approach to Identify Novel Ochratoxin A Hydrolyzing Enzyme

Ochratoxin A (OTA), a mycotoxin that is of utmost concern in food and feed safety, is produced by fungal species that mainly belong to the Aspergillus and Penicillium genera. The development of mitigation strategies to reduce OTA content along the supply chains is key to ensuring safer production of food and feed. Enzyme-based strategies are among the most promising methods due to their specificity, efficacy, and multi-situ applicability. In particular, some enzymes are already known for hydrolyzing OTA into ochratoxin alpha (OTα) and phenylalanine (Phe), eventually resulting in detoxification action. Therefore, the discovery of novel OTA hydrolyzing enzymes, along with the advancement of an innovative approach for their identification, could provide a broader basis to develop more effective mitigating strategies in the future. In the present study, a hybrid in silico/in vitro workflow coupling virtual screening with enzymatic assays was applied in order to identify novel OTA hydrolyzing enzymes. Among the various hits, porcine carboxypeptidase B was identified for the first time as an effective OTA hydrolyzing enzyme. The successful experimental endorsement of findings of the workflow confirms that the presented strategy is suitable for identifying novel OTA hydrolyzing enzymes, and it might be relevant for the discovery of other mycotoxin- mitigating enzymes.

Reduced toxicity of 3-epi-deoxynivalenol and de-epoxy-deoxynivalenol through deoxynivalenol bacterial biotransformation: In vivo analysis in piglets

Ingestion of deoxynivalenol (DON), one of the most common mycotoxin contaminants of cereals, leads to adverse effects for animal and human health. Bacterial biotransformation is a strategy to mitigate the toxicity of this mycotoxin. The present study aims to evaluate the toxicity of two bacterial biotranformation products of DON: 3-epi-deoxynivalenol (3-epi-DON) and de-epoxy-deoxynivalenol (DOM-1) through zootechnical, hematological, histological and immunological assays. Twenty-four 4-weeks-old piglets received a control diet or a diet contaminated with 3 mg kg^-1 DON, DOM-1, or 3-epi-DON for 7 days. Sample tissues were collected for histomorphometrical analysis, expression of cytokines and cell protein junctions. The zootechnical and hematological parameters were not modulated by any treatment. Ingestion of DON induced histological alterations in the intestine, liver and lymphoid organs, as well as an overexpression of pro-inflammatory cytokines, E-cadherin and occludin. These changes were not observed in piglets receiving the DOM-1 and 3-epi-DON contaminated diets. Pigs fed 3-epi-DON contaminated diet showed an increase in IgM levels in comparison with other diets, while no change was observed in IgA and IgG levels among the diets. Our results indicate that DOM-1 and 3-epi-DON are not toxic for piglets; thus bacterial biotransformation seems to be a sustainable alternative to reduce mycotoxin toxicity.

Co-occurrence of DON and Emerging Mycotoxins in Worldwide Finished Pig Feed and Their Combined Toxicity in Intestinal Cells

Food and feed can be naturally contaminated by several mycotoxins, and concern about the hazard of exposure to mycotoxin mixtures is increasing. In this study, more than 800 metabolites were analyzed in 524 finished pig feed samples collected worldwide. Eighty-eight percent of the samples were co-contaminated with deoxynivalenol (DON) and other regulated/emerging mycotoxins. The Top 60 emerging/regulated mycotoxins co-occurring with DON in pig feed shows that 48%, 13%, 8% and 12% are produced by Fusarium, Aspergillus, Penicillium and Alternaria species, respectively. Then, the individual and combined toxicity of DON and the 10 most prevalent emerging mycotoxins (brevianamide F, cyclo-(L-Pro-L-Tyr), tryptophol, enniatins A1, B, B1, emodin, aurofusarin, beauvericin and apicidin) was measured at three ratios corresponding to pig feed contamination. Toxicity was assessed by measuring the viability of intestinal porcine epithelial cells, IPEC-1, at 48-h. BRV-F, Cyclo and TRPT did not alter cell viability. The other metabolites were ranked in the following order of toxicity: apicidin > enniatin A1 > DON > beauvericin > enniatin B > enniatin B1 > emodin > aurofusarin. In most of the mixtures, combined toxicity was similar to the toxicity of DON alone. In terms of pig health, these results demonstrate that the co-occurrence of emerging mycotoxins that we tested with DON does not exacerbate toxicity.

Twenty-Eight Fungal Secondary Metabolites Detected in Pig Feed Samples: Their Occurrence, Relevance and Cytotoxic Effects In Vitro

Feed samples are frequently contaminated by a wide range of chemically diverse natural products, which can be determined using highly sensitive analytical techniques. Next to already well-investigated mycotoxins, unknown or unregulated fungal secondary metabolites have also been found, some of which at significant concentrations. In our study, 1141 pig feed samples were analyzed for more than 800 secondary fungal metabolites using the same LC-MS/MS method and ranked according to their prevalence. Effects on the viability of the 28 most relevant were tested on an intestinal porcine epithelial cell line (IPEC-J2). The most frequently occurring compounds were determined as being cyclo-(L-Pro-L-Tyr), moniliformin, and enniatin B, followed by enniatin B1, aurofusarin, culmorin, and enniatin A1. The main mycotoxins, deoxynivalenol and zearalenone, were found only at ranks 8 and 10. Regarding cytotoxicity, apicidin, gliotoxin, bikaverin, and beauvericin led to lower IC50 values, between 0.52 and 2.43 µM, compared to deoxynivalenol (IC50 = 2.55 µM). Significant cytotoxic effects were also seen for the group of enniatins, which occurred in up to 82.2% of the feed samples. Our study gives an overall insight into the amount of fungal secondary metabolites found in pig feed samples compared to their cytotoxic effects in vitro.

Interactions between plant-derived oestrogenic substances and the mycoestrogen zearalenone in a bioassay with MCF-7 cells

Human and animal diets may contain several non-steroidal oestrogenic compounds which originate either from plants (phytoestrogens) or from fungi that infect plants (mycoestrogens such as zearalenone (ZEN)). Phytoestrogens may compete with ZEN in binding to the oestrogen receptor β and thereby may counteract the oestrogenic activity of ZEN. Using a modified version of the E-screen assay, plant-derived oestrogenic substances were tested for their proliferative or anti-proliferative effect on oestrogen-dependent MCF-7 cells. The samples were additionally tested for their ability to influence the oestrogenic activity of ZEN (1 μM). Among the individual substances tested, 8-prenylnaringenin had the strongest effect, as cell proliferation was increased by 78% at the lowest concentration (0.23 μM), and by 167% at the highest concentration (29.4 μM). Coumestrol (5.83 μM) increased cell proliferation by 39%, and genistein (370 μM) by 61%, respectively. Xanthohumol and enterolactone did not stimulate cell proliferation significantly. In the co-incubation experiments with ZEN, none of the single substances was able to decrease the oestrogenic activity of ZEN. Only for 8-prenylnaringenin (14.7 and 29.4 μM) was a trend towards an increase in the ZEN-induced cell proliferation up to 72% observed. In conclusion, with the exception of 8-prenylnaringenin, no substantial interaction between phytoestrogens and the mycotoxin ZEN could be detected using a bioassays with MCF-7 cells.

MicroRNAs in porcine uterus and serum are affected by zearalenone and represent a new target for mycotoxin biomarker discovery

The mycotoxin zearalenone (ZEN) poses a risk to animal health because of its estrogenic effects. Diagnosis of ZEN-induced disorders remains challenging due to the lack of appropriate biomarkers. In this regard, circulating microRNAs (small non-coding RNAs) have remarkable potential, as they can serve as indicators for pathological processes in tissue. Thus, we combined untargeted and targeted transcriptomics approaches to investigate the effects of ZEN on the microRNA expression in porcine uterus, jejunum and serum, respectively. To this end, twenty-four piglets received uncontaminated feed (Control) or feed containing 0.17 mg/kg ZEN (ZEN low), 1.46 mg/kg ZEN (ZEN medium) and 4.58 mg/kg ZEN (ZEN high). After 28 days, the microRNA expression in the jejunum remained unaffected, while significant changes in the uterine microRNA profile were observed. Importantly, 14 microRNAs were commonly and dose-dependently affected in both the ZEN medium and ZEN high group, including microRNAs from the miR-503 cluster (i.e. ssc-miR-424-5p, ssc-miR-450a, ssc-miR-450b-5p, ssc-miR-450c-5p, ssc-miR-503 and ssc-miR-542-3p). Predicted target genes for those microRNAs are associated with regulation of gene expression and signal transduction (e.g. cell cycle). Although the effects in serum were less pronounced, receiver operating characteristic analysis revealed that several microRNA ratios were able to discriminate properly between non-exposed and ZEN-exposed pigs (e.g. ssc-miR-135a-5p/ssc-miR-432-5p, ssc-miR-542-3p/ssc-miR-493-3p). This work sheds new light on the molecular mechanisms of ZEN, and fosters biomarker discovery.

Global Mycotoxin Occurrence in Feed: A Ten-Year Survey

Mycotoxins contaminating animal feed can exert toxic effects in animals and be transferred into animal products. Therefore, mycotoxin occurrence in feed should be monitored. To this end, we performed a large-scale global survey of mycotoxin contamination in feed and assessed regional differences and year-to-year variation of mycotoxin occurrence. Concentrations of aflatoxin B1, zearalenone, fumonisins, ochratoxin A, deoxynivalenol, and T-2 toxin were analyzed in 74,821 samples of feed and feed raw materials (e.g., maize, wheat, soybean) collected from 100 countries from 2008 to 2017. In total, 88% of the samples were contaminated with at least one mycotoxin. Mycotoxin occurrence showed distinct regional trends and climate was a key determinant governing these trends. In most regions, the majority of samples complied with maximum levels and guidance values for mycotoxins in animal feed that are in effect in the European Union. However, 41.1%, 38.5%, and 20.9% of samples from South Asia, Sub-Saharan Africa, and Southeast Asia, respectively, exceeded the maximum level for aflatoxin B1 (20 µg/kg). In several regions, mycotoxin concentrations in maize showed a pronounced year-to-year variation that could be explained by rainfall or temperature during sensitive periods of grain development. A large fraction of samples (64%) was co-contaminated with ≥ 2 mycotoxins. Most frequently observed mycotoxin mixtures were combinations of deoxynivalenol, zearalenone, and fumonisins, as well as fumonisins and aflatoxin B1. Deoxynivalenol and zearalenone concentrations were correlated in maize and wheat. In conclusion, according to an extensive global survey, mycotoxin (co-)contamination of animal feed is common, shows regional trends, and is governed in part by climate and weather.

Multi-mycotoxin screening of feed and feed raw materials from Africa

As animal feed is prone to infestation with mycotoxin-producing fungi, mycotoxin contamination of feed should be monitored. Here, we report a multi-mycotoxin survey of feed samples from Africa. We determined the concentrations of aflatoxins, fumonisins, deoxynivalenol, T-2 toxin, zearalenone and ochratoxin A in 1,045 samples of finished feed and feed raw materials (maize, maize silage, other cereals, etc.) from South Africa and 318 samples from Algeria, Tunisia, Morocco, Senegal, Côte d’Ivoire, Nigeria, Ghana, Namibia, Uganda, Kenya, Tanzania, Zambia and Madagascar. We compared the measured mycotoxin concentrations to regulatory limits or guidance values that are in effect in the European Union and analysed the co-occurrence of these mycotoxins. To determine the occurrence of other fungal secondary metabolites, a subset of the samples was analysed using a multi-analyte liquid chromatography tandem mass spectrometry-based method for the simultaneous detection of over 700 fungal metabolites. We found that 33.3% of maize samples and 54.4% of finished feed samples from Senegal, Côte d’Ivoire, Nigeria, Ghana, Namibia, Uganda, Kenya and Tanzania exceeded the European regulatory limit of 20 ng/g aflatoxins. The Fusarium mycotoxins zearalenone, fumonisins and deoxynivalenol were prevalent in all commodities from all countries, but concentrations were in most cases below European guidance values. Concentrations of deoxynivalenol and zearalenone were correlated. Several other Fusarium metabolites occurred frequently (e.g. moniliformin, beauvericin, aurofusarin) or in high concentrations (e.g. aurofusarin, fusaproliferin). Furthermore, high levels of diplodiatoxin were occasionally detected in samples from South Africa and the Alternaria metabolite tenuazonic acid was prevalent and reached high concentrations. In conclusion, aflatoxins frequently occurred in African feed samples in potentially unsafe concentrations. While Fusarium mycotoxins mostly occurred in concentrations below European guidance values, a correlation between deoxynivalenol and zearalenone concentrations suggests that toxicological interactions of these compounds deserve attention. Several less investigated fungal secondary metabolites occurred frequently or reached high concentrations.

Enzymatic hydrolysis of fumonisins in the gastrointestinal tract of broiler chickens

Fumonisins (FB) are among the most frequently detected mycotoxins in feedstuffs and finished feed, and recent data suggest that the functions of the gastrointestinal tract (GIT) in poultry species might be compromised at doses ranging from 10 to 20 mg/kg, close to field incidences and below the US and EU guidelines. Strategies are therefore necessary to reduce the exposure of poultry to FB. In the present study, we assessed the efficacy of fumonisin esterase FumD (EC 3.1.1.87, commercial name FUMzyme®) to cleave the tricarballylic acid side chains of FB, leading to the formation of non-toxic hydrolyzed fumonisins in the GIT of broiler chickens. Broiler chickens were fed for 14 d (7 to 21 d of age) 3 different diets (6 birds/cage, 6 cages/diet), i) control feed (negative control group), ii) feed contaminated with 10 mg FB/kg (FB group), and iii) feed contaminated with 10 mg FB/kg and supplemented with 100 units of FUMzyme®/kg (FB+FUMzyme® group). To determine the degree of reduction of FB in the GIT, 2 characteristics were analyzed. First, the sphinganine-to-sphingosine ratio in the serum and liver was determined as a biomarker of effect for exposure to FB. Second, the concentration of fumonisin B1 and its hydrolyzed forms was evaluated in the gizzard, the proximal and distal parts of the small intestine, and the excreta. Significantly reduced sphinganine-to-sphingosine ratios in the serum and liver of the FB+FUMzyme® group (serum: 0.15 ± 0.01; liver: 0.17 ± 0.01) compared to the FB group (serum: 0.20 ± 0.01; liver: 0.29 ± 0.03) proved that supplementation of broiler feed with FUMzyme® was effective in partially counteracting the toxic effect of dietary FB. Likewise, FB concentrations in digesta and excreta were significantly reduced in the FB+FUMzyme® group compared to the FB group (P < 0.05; up to 75%). FUMzyme® furthermore partially counteracted FB-induced up-regulation of cytokine gene expression (IL-8 and IL-10) in the jejunum. The FB group showed significantly higher gene expression of IL-8 and IL-10 compared to the negative control group (IL-8: fold change = 2.9 ± 1.1, P < 0.05; IL-10: fold change = 3.6 ± 1.4, P < 0.05), whereas IL-8 and IL-10 mRNA levels were not significantly different in the FB+FUMzyme®® group compared to the other 2 groups. In conclusion, FUMzyme® is suitable to detoxify FB in chickens and maintain gut functions.

Bovine Peripheral Blood Mononuclear Cells Are More Sensitive to Deoxynivalenol Than Those Derived from Poultry and Swine

Deoxynivalenol (DON) is one of the most prevalent mycotoxins, contaminating cereals and cereal-derived products. Its derivative deepoxy-deoxynivalenol (DOM-1) is produced by certain bacteria, which either occur naturally or are supplemented in feed additive. DON-induced impairments in protein synthesis are particularly problematic for highly proliferating immune cells. This study provides the first comparison of the effects of DON and DOM-1 on the concanavalin A-induced proliferation of porcine, chicken, and bovine peripheral blood mononuclear cells (PBMCs). Therefore, isolated PBMCs were treated with DON (0.01–3.37 µM) and DOM-1 (1.39–357 µM) separately, and proliferation was measured using a bromodeoxyuridine (BrdU) assay. Although pigs are considered highly sensitive to DON, the present study revealed a substantially higher sensitivity of bovine (IC50 = 0.314 µM) PBMCs compared to chicken (IC50 = 0.691 µM) and porcine (IC50 = 0.693 µM) PBMCs. Analyses on the proliferation of bovine T-cell subsets showed that all major subsets, namely, CD4⁺, CD8β⁺, and γδ T cells, were affected to a similar extent. In contrast, DOM-1 did not affect bovine PBMCs, but reduced the proliferation of chicken and porcine PBMCs at the highest tested concentration (357 µM). Results confirm the necessity of feed additives containing DON-to-DOM-1-transforming bacteria and highlights species-specific differences in the DON sensitivity of immune cells.

Mycotoxins co-contamination: Methodological aspects and biological relevance of combined toxicity studies

Mycotoxins are secondary fungal metabolites produced mainly by Aspergillus, Penicillium, and Fusarium. As evidenced by large-scale surveys, humans and animals are simultaneously exposed to several mycotoxins. Simultaneous exposure could result in synergistic, additive or antagonistic effects. However, most toxicity studies addressed the effects of mycotoxins separately. We present the experimental designs and we discuss the conclusions drawn from in vitro experiments exploring toxicological interactions of mycotoxins. We report more than 80 publications related to mycotoxin interactions. The studies explored combinations involving the regulated groups of mycotoxins, especially aflatoxins, ochratoxins, fumonisins, zearalenone and trichothecenes, but also the "emerging" mycotoxins beauvericin and enniatins. Over 50 publications are based on the arithmetic model of additivity. Few studies used the factorial designs or the theoretical biology-based models of additivity. The latter approaches are gaining increased attention. These analyses allow determination of the type of interaction and, optionally, its magnitude. The type of interaction reported for mycotoxin combinations depended on several factors, in particular cell models and the tested dose ranges. However, synergy among Fusarium toxins was highlighted in several studies. This review indicates that well-addressed in vitro studies remain valuable tools for the screening of interactive potential in mycotoxin mixtures.

Effects of dietary acidifier supplementation on broiler growth performance, digestive and immune function indices

The effect of dietary acidifier (AC) supplementation in combination or not with avilamycin (AV) was evaluated on broiler performance, nutrient digestibility, gizzard pH, activity of digestive enzymes and relative expression of cytokines. A 2 × 2 factorial experimental design with inclusion of AC (0 and 1 g/kg of diet) and AV (0 and 2.5 mg/kg of diet) as the main factors was implemented. Subsequently, 544-day-old male Cobb broilers were allocated in four treatments (i.e. C – no additions, AC; AV and ACAV), each having eight replicates of 17 broilers, for 6 weeks. Overall bodyweight gain (BWG) was improved (PAC = 0.035) by AC addition. BWG and feed conversion ratio were improved (P ≤ 0.05) by AV addition in all growth periods and overall. Dry matter, organic matter digestibility and energy retention were improved by AC (PAC = 0.050, PAC = 0.045 and PAC = 0.020, respectively), or AV (PAV = 0.018, PAV = 0.013 and PAV = 0.012, respectively). In addition AV supplementation improved digestibility of ether extracts (PAV = 0.022) and crude protein (PAV = 0.042). Pancreatic trypsin activity was lower in AC (PAC = 0.027) or AV (PAV ≤ 0.001) supplemented diets. An AC × AV effect on gizzard pH (PAC × AV = 0.034) was noted. Expression of interferon-γ (PAV = 0.010), interleukin (IL) 18 (PAV = 0.048) and inducible nitric oxide synthase 2 (PAV = 0.035) in spleen were downregulated by AV. An upregulation of IL10 (PAC × AV = 0.018), IL18 (PAC × AV = 0.002) and IL22 (PAC × AV = 0.030) in the caecal tonsils was shown for the combined ACAV supplementation. In conclusion, dietary AC supplementation improved performance, nutrient digestibility and energy retention, irrespective of AV inclusion. This study has provided evidence for potential links between digestive and immune function indices with growth performance improvements.

Co-Occurrence of Regulated, Masked and Emerging Mycotoxins and Secondary Metabolites in Finished Feed and Maize-An Extensive Survey

Global trade of agricultural commodities (e.g., animal feed) requires monitoring for fungal toxins. Also, little is known about masked and emerging toxins and metabolites. 1926 samples from 52 countries were analysed for toxins and metabolites. Of 162 compounds detected, up to 68 metabolites were found in a single sample. A subset of 1113 finished feed, maize and maize silage samples containing 57 compounds from 2012 to 2015 from 44 countries was investigated using liquid chromatography and mass spectrometry. Deoxynivalenol (DON), zearalenone (ZEN) and fumonisins showed large increases of annual medians in Europe. Within a region, distinct trends were observed, suggesting importance of local meteorology and cultivars. In 2015, median DON concentrations increased to 1400 μ g·kg - 1 in Austria, but were stable in Germany at 350 μ g·kg - 1 . In 2014, enniatins occurred at median concentrations of 250 μ g·kg - 1 in Europe, at levels similar to DON and ZEN. The latter were frequently correlated with DON-3-glucoside and ZEN-14-sulfate. Co-occurrence of regulated toxins was frequent with e.g., enniatins, and moniliformin. Correlation was observed between DON and DON-3-glucoside and with beauvericin. Results indicate that considerably more than 25% of agricultural commodities could be contaminated with mycotoxins as suggested by FAO, although this is at least partly due to the lower limits of detection in the current survey. Observed contamination percentages ranged from 7.1 to 79% for B trichothecenes and 88% for ZEN.

Deoxynivalenol and its metabolite deepoxy-deoxynivalenol: multi-parameter analysis for the evaluation of cytotoxicity and cellular effects

The mycotoxin deoxynivalenol (DON) contaminates agricultural commodities worldwide, posing health threats to humans and animals. Associated with DON are derivatives, such as deepoxy-deoxynivalenol (DOM-1), produced by enzymatic transformation of certain intestinal bacteria, which are naturally occurring or applied as feed additives. Using differentiated porcine intestinal epithelial cells (IPEC-J2), we provide the first multi-parameter comparative cytotoxicity analysis of DON and DOM-1, based on the parallel evaluation of lysosomal activity, total protein content, membrane integrity, mitochondrial metabolism and ATP synthesis. The study investigated the ability of DON and—for the first time of its metabolite DOM-1—to induce apoptosis, mitogen-activated protein kinase (MAPK) signalling, oxidative events and alterations of mitochondrial structure in porcine intestinal epithelial cells (IECs). The degree of DON toxicity strongly varied, depending on the cytotoxicity parameter evaluated. DON compromised viability according to the parameters of lysosomal activity, total protein content and membrane integrity, but increased viability according to assays based on mitochondrial metabolism and ATP synthesis. DON induced expression of cleaved caspase-3 (maximum induction 3.9-fold) and MAPK p38 and p42/p44 (maximum induction 2.51- and 2.30-fold, respectively). DON altered mitochondrial morphology, but did not increase intracellular ROS. DOM-1-treated IPEC-J2 remained unaffected at equimolar concentrations in all assays, thereby confirming the safety of feed additives using DON- to DOM-1-transforming bacteria. The study additionally highlights that an extensive multi-parameter analysis significantly contributes to the quality of in vitro data.

In vitro inhibitory effects of plant-derived by-products against Cryptosporidium parvum

Disposal of organic plant wastes and by-products from the food or pharmaceutical industries usually involves high costs. In the present study, 42 samples derived from such by-products were screened in vitro against Cryptosporidium parvum, a protozoan parasite that may contaminate drinking water and cause diarrhoea. The novel bioassay was previously established in the microtitre plate format. Human ileocaecal adenocarcinoma (HCT-8) cell cultures were seeded with C. parvum oocysts and parasite development was monitored by an indirect fluorescent antibody technique (IFAT) and microscopic assessment for clusters of secondary infection (CSI). Minimum inhibitory concentrations (MICs) and potential detrimental effects on the host cells were determined. An ethanolic extract from olive (Olea europaea) pomace, after oil pressing and phenol recovery, reproducibly inhibited C. parvum development (MIC = 250-500 μg mL(-1), IC50 = 361 (279-438) μg mL(-1), IC90 = 467 (398-615) μg mL(-1)). Accordingly, tyrosol, hydroxytyrosol, trans-coniferyl alcohol and oleuropein were selected as reference test compounds, but their contributions to the observed activity of the olive pomace extract were insignificant. The established test system proved to be a fast and efficient assay for identifying anti-cryptosporidial activities in biological waste material and comparison with selected reference compounds.

Isolation and characterisation of enzymatic zearalenone hydrolysis reaction products

Zearalenone (ZEA) is an oestrogenic mycotoxin produced by several Fusarium species, and it frequently contaminates cereals used for food or animal feed. A ZEA-lactonase of Gliocladium roseum was previously described to hydrolyse ZEA to an unstable intermediate, which spontaneously decarboxylates to non-oestrogenic, decarboxylated hydrolysed ZEA (DHZEN). We expressed a codon-optimised version of the ZEA-lactonase (ZHD101) gene of G. roseum MA 918 with a secretion leader in Pichia pastoris and purified the recombinant enzyme from culture supernatant by His-tag mediated affinity chromatography. After incubation of the enzyme with ZEA, we detected the previously elusive primary reaction product hydrolysed ZEA (HZEN) by liquid chromatography tandem mass spectrometry, purified it by preparative high-performance liquid chromatography, and confirmed its postulated structure ((E)-2,4-dihydroxy-6-(10-hydroxy-6-oxo-1-undecen-1-yl)benzoic acid) by nuclear magnetic resonance techniques. Spontaneous decarboxylation to DHZEN ((E)-1-(3,5-dihydroxy-phenyl)-10-hydroxy-1-undecen-6-one), but not to a previously reported isomer, was observed. Biomass resuspensions of G. roseum strains MA 918 and the strains used for previous work, NBRC 7063 and ATCC 8684, all converted ZEA to HZEN, DHZEN, and further unknown metabolites. We studied partitioning of HZEN and DHZEN between aqueous phases and organic solvents, and found that HZEN did not partition into chloroform as extraction solvent, under the conditions used by previous authors. In contrast, extraction with ethyl acetate at pH 2.0 was suitable for simultaneous extraction of HZEN and DHZEN. The detection of HZEN and its availability as an analytical standard may assist further work towards possible application of ZEA-lactonase (e.g. determining kinetic parameters) for detoxification of ZEA.

Fumonisin B₁ (FB₁) Induces Lamellar Separation and Alters Sphingolipid Metabolism of In Vitro Cultured Hoof Explants

One of the most important hoof diseases is laminitis. Yet, the pathology of laminitis is not fully understood. Different bacterial toxins, e.g. endotoxins or exotoxins, seem to play an important role. Additionally, ingestion of mycotoxins, toxic secondary metabolites of fungi, might contribute to the onset of laminitis. In this respect, fumonsins are of special interest since horses are regarded as species most susceptible to this group of mycotoxins. The aim of our study was to investigate the influence of fumonisin B₁ (FB₁) on primary isolated epidermal and dermal hoof cells, as well as on the lamellar tissue integrity and sphingolipid metabolism of hoof explants in vitro. There was no effect of FB₁ at any concentration on dermal or epidermal cells. However, FB₁ significantly reduced the separation force of explants after 24 h of incubation. The Sa/So ratio was significantly increased in supernatants of explants incubated with FB₁ (2.5–10 µg/mL) after 24 h. Observed effects on Sa/So ratio were linked to significantly increased sphinganine concentrations. Our study showed that FB₁ impairs the sphingolipid metabolism of explants and reduces lamellar integrity at non-cytotoxic concentrations. FB₁ might, therefore, affect hoof health. Further in vitro and in vivo studies are necessary to elucidate the effects of FB₁ on the equine hoof in more detail.

Concentration Dependent Influence of Lipopolysaccharides on Separation of Hoof Explants and Supernatant Lactic Acid Concentration in an Ex Vivo/In Vitro Laminitis Model

Laminitis is one of the most common diseases in horses. It is not only painful for the animal, but also has a significant financial impact on the equine industry. This multifactorial disease affects the connective tissue of the hoof. However, the pathogenesis of laminitis is still not fully understood. Endotoxins, also known as lipopolysaccharides (LPS), and bacterial exotoxins seem to play an important role during the development of laminitis. The aim of our study was to investigate the effect of increasing LPS concentrations (0, 2.5, 5, 10, and 100 μg/mL) on cell viability of isolated epidermal and dermal hoof cells as well as on the tissue integrity of hoof explants. Furthermore, glucose, acetic acid, lactic acid, and propionic acid concentrations in explant supernatants were measured to evaluate the energy metabolism in the hoof tissue. LPS did not exhibit cytotoxic effects on epidermal or dermal cells. Force required to separate LPS treated hoof explants decreased in a concentration dependent manner. Specifically, explants incubated with 10 and 100 μg/mL needed significantly less force to separate compared to control explants. Lactic acid concentrations were significantly decreased in explants incubated with 5, 10, or 100 μg/mL LPS, while glucose, acetic acid and propionic acid concentrations were unaffected by LPS treatment. Our study indicates that LPS has no cytotoxic effect on epidermal and dermal cells isolated from hoof tissue, but impairs integrity of hoof explants. In addition, LPS led to an alteration of the lactic acid production in the lamellar tissue. Since our data highlight that LPS can affect the integrity of the equine hoof tissue in vitro, endotoxins should be further explored for their contribution to facilitate the development of laminitis.

In vitro binding assessment and in vivo efficacy of several adsorbents against aflatoxin B1

Aflatoxins are a class of mycotoxins that impair poultry health and performance. Some clays have the ability to adsorb aflatoxins. In our study, mineralogical composition of the tested clays was confirmed by powder X-ray diffraction and simultaneous thermal analysis and their properties like pH, electrical conductivity, exchangeable cations, cation exchange capacity and clay content were determined. For their in vitro assessment regarding aflatoxin B1 (AFB1) adsorption, adsorption tests under ‘intensified conditions’ (low adsorbent and high toxin concentration) were carried out in buffers at various pH values and in real gastric juice followed by isothermal analysis in phosphate buffer. In vivo we used a completely randomised design with 4 replicate pens of 5 chicks assigned to each dietary treatment from hatch to 21 days. Dietary treatments included a negative and a positive control diet (2 mg/kg AFB1), and treatment groups receiving 2 mg/kg AFB1 and 0.5% of one of 8 adsorbents. Results of in vitro experiments ranked the adsorbents as ‘good’ (R, MB, B7, M32, M34, M5; 6 bentonites containing a cis-vacant smectite), ‘average’ (bentonite C2 containing a trans-vacant smectite) or ‘poor’ (zeolite Z08, containing clinoptilolite). The addition of AFB1 significantly reduced feed intake and/or body weight gain of the chicks compared to the negative control and to the treatment groups, except for C2 and Z08. Except Z08, all adsorbents numerically decreased the liver weight compared to the AFB1-fed group. Kidney weights were significantly increased by the addition of AFB1 compared to the control and most adsorbents, except C2 and Z08. Similarly, ‘good’ adsorbents significantly prevented the decrease in serum albumin and serum total protein. The ability of adsorbents to ameliorate AFB1 toxicity in poultry basically correlated with the in vitro findings meaning that ‘poor’ and ‘average’ adsorbents did not (Z08) or only partially (C2) protect against AFB1 in vivo.

Characterisation and determination of metabolites formed by microbial and enzymatic degradation of ergot alkaloids

Ergot alkaloids are frequent contaminants of cereal crops. Strategies for their inactivation include the use of microorganisms or enzymes as feed additives capable of degrading ergot alkaloids. Recently, an ergopeptine-degrading Rhodococcus erythropolis strain MTHt3 (DSM 25948) has been isolated from soil and the involved enzymes ErgA and ErgB have been identified. The aim of the current study was to characterise the metabolites formed by degradation of various ergopeptines with the MTHt3 strain, its lysate and the purified enzyme ErgA. Using preparative HPLC, 1H-, 13C- and 2D-NMR as well as HR-MS measurements, two main groups of metabolites formed during microbial and enzymatic degradation of ergopeptines were identified: diketopiperazines (cyclic dipeptides, DKPs) and unstable ergine hydroxy carboxylic acids. However, degradation by strain, lysate and enzyme yielded different end-products. Whereas DKPs were transient and lysergic acid the only final product upon incubation of ergopeptines with the R. erythropolis strain, incubation with the lysate resulted in formation of lysergic acid and two isomeric DKPs at different ratios. Enzymatic degradation by ErgA yielded only one DKP isomer and ended at the stage of the ergine hydroxy carboxylic acids which then spontaneously degraded to ergine. In conclusion, we succeeded in identification of metabolites formed by microbial and enzymatic degradation of ergot alkaloids which is a crucial step in the future development of feed additives for gastro intestinal detoxification of ergopeptines in farm animals.

Prevalence and effects of mycotoxins on poultry health and performance, and recent development in mycotoxin counteracting strategies

Extensive research over the last couple of decades has made it obvious that mycotoxins are commonly prevalent in majority of feed ingredients. A worldwide mycotoxin survey in 2013 revealed 81% of around 3,000 grain and feed samples analyzed had at least 1 mycotoxin, which was higher than the 10-year average (from 2004 to 2013) of 76% in a total of 25,944 samples. The considerable increase in the number of positive samples in 2013 may be due to the improvements in detection methods and their sensitivity. The recently developed liquid chromatography coupled to (tandem) mass spectrometry allows the inclusion of a high number of analytes and is the most selective, sensitive, and accurate of all the mycotoxin analytical methods. Mycotoxins can affect the animals either individually or additively in the presence of more than 1 mycotoxin, and may affect various organs such as gastrointestinal tract, liver, and immune system, essentially resulting in reduced productivity of the birds and mortality in extreme cases. While the use of mycotoxin binding agents has been a commonly used counteracting strategy, considering the great diversity in the chemical structures of mycotoxins, it is very obvious that there is no single method that can be used to deactivate mycotoxins in feed. Therefore, different strategies have to be combined in order to specifically target individual mycotoxins without impacting the quality of feed. Enzymatic or microbial detoxification, referred to as "biotransformation" or "biodetoxification," utilizes microorganisms or purified enzymes thereof to catabolize the entire mycotoxin or transform or cleave it to less or non-toxic compounds. However, the awareness on the prevalence of mycotoxins, available modern techniques to analyze them, the effects of mycotoxicoses, and the recent developments in the ways to safely eliminate the mycotoxins from the feed are very minimal among the producers. This symposium review paper comprehensively discusses the above mentioned aspects.

Rhodococcus erythropolis MTHt3 biotransforms ergopeptines to lysergic acid

Background

Ergopeptines are a predominant class of ergot alkaloids produced by tall fescue grass endophyte Neotyphodium coenophialum or cereal pathogen Claviceps purpurea. The vasoconstrictive activity of ergopeptines makes them toxic for mammals, and they can be a problem in animal husbandry.

Results

We isolated an ergopeptine degrading bacterial strain, MTHt3, and classified it, based on its 16S rDNA sequence, as a strain of Rhodococcus erythropolis (Nocardiaceae, Actinobacteria). For strain isolation, mixed microbial cultures were obtained from artificially ergot alkaloid-enriched soil, and provided with the ergopeptine ergotamine in mineral medium for enrichment. Individual colonies derived from such mixed cultures were screened for ergotamine degradation by high performance liquid chromatography and fluorescence detection. R. erythropolis MTHt3 converted ergotamine to ergine (lysergic acid amide) and further to lysergic acid, which accumulated as an end product. No other tested R. erythropolis strain degraded ergotamine. R. erythropolis MTHt3 degraded all ergopeptines found in an ergot extract, namely ergotamine, ergovaline, ergocristine, ergocryptine, ergocornine, and ergosine, but the simpler lysergic acid derivatives agroclavine, chanoclavine, and ergometrine were not degraded. Temperature and pH dependence of ergotamine and ergine bioconversion activity was different for the two reactions.

Conclusions

Degradation of ergopeptines to ergine is a previously unknown microbial reaction. The reaction end product, lysergic acid, has no or much lower vasoconstrictive activity than ergopeptines. If the genes encoding enzymes for ergopeptine catabolism can be cloned and expressed in recombinant hosts, application of ergopeptine and ergine degrading enzymes for reduction of toxicity of ergot alkaloid-contaminated animal feed may be feasible.

Impact of a probiotic, inulin, or their combination on the piglets' microbiota at different intestinal locations

Natural feed additives are used to maintain health and to promote performance of pigs without antibiotics. Effects of a probiotic, inulin, and their combination (synbiotic), on the microbial diversity and composition at different intestinal locations were analysed using denaturing gradient gel electrophoresis (DGGE), real-time PCR, and 16S rRNA gene pyrosequencing. Bacterial diversity assessed by DGGE and/or pyrosequencing was increased by inulin in all three gut locations and by the synbiotic in the caecum and colon. In contrast, the probiotic did only affect the microbiota diversity in the ileum. Shifts in the DGGE microbiota profiles of the caecum and colon were detected for the pro- and synbiotic fed animals, whereas inulin profiles were more similar to the ones of the control. 16S rRNA gene pyrosequencing revealed that all three additives could reduce Escherichia species in each gut location, indicating a potential beneficial effect on the gut microbiota. An increase of relative abundance of Clostridiaceae in the large intestine was found in the inulin group and of Enterococcaceae in the ileum of probiotic fed pigs. Furthermore, real-time PCR results showed that the probiotic and synbiotic increased bifidobacterial numbers in the ileum, which was supported by sequencing results. The probiotic and inulin, to different extents, changed the diversity, relative abundance of phylotypes, and community profiles of the porcine microbiota. However, alterations of the bacterial community were not uniformly between gut locations, demonstrating that functionality of feed additives is site specific. Therefore, gut sampling from various locations is crucial when investigations aim to identify the composition of a healthy gut microbiota after its manipulation through feed additives.

Evaluation of the efficacy of sequential or continuous administration of probiotics and phytogenics in broiler diets

Three dietary combinations of probiotics and phytogenics administered sequentially or continuously were assessed for their effects on broiler performance, nutrient digestibility, caecal microbiota composition, volatile fatty acid (VFA) pattern and plasma total antioxidant capacity (TAC). One-day-old Cobb male broilers (n = 525) were allocated to five experimental treatments for 42 days. Each treatment had three replicates of 35 broilers each. Depending on the time-frame of sequential or continuous addition in the basal diet (BD) of the probiotics (108 CFU/kg BD) and phytogenics (125 mg/kg BD), experimental treatments were: control (no additions, Days 1–42); PE1, probiotic Days 1–14 and phytogenic Days 15–42; PE2, probiotic Days 1–28 and phytogenic Days 29–42; PE3, probiotic and phytogenic continuously (Days 1–42); and A (2.5 mg avilamycin/kg diet, Days 1–42). There was no loss of probiotic viability upon mixing with the phytogenic for up to 7 days. Overall bodyweight gain was higher (P = 0.025) in the control and PE1 than PE2 and PE3, whereas Treatment A was intermediate and not different from the rest. Overall feed intake in the control was the highest (P = 0.003). Treatments PE1, PE2 and PE3 had better (P = 0.004) overall feed conversion ratio (FCR) than the control. The FCR in PE1 and PE3 did not differ from A, which had the best FCR. Mortality did not differ among treatments. Nutrient digestibility and caecal microbiota composition did not differ among treatments. However, differences (P ≤ 0.05) in caecal VFA pattern were noted, with the control having the lowest acetate molar ratio as well as the highest sum of valeric, hexanoic and heptanoic acids. Plasma TAC in the control was lower than in PE3, PE1 and PE2 at Day 14 (P < 0.001) and PE1 (P = 0.003) at Day 42. The concept of sequential or throughout probiotic and phytogenic administration showed promising results regarding feed efficiency and plasma TAC.

Effect of dietary inclusion level of a multi-species probiotic on broiler performance and two biomarkers of their caecal ecology

The effect of the dietary inclusion level of a three-species probiotic on broiler performance, nutrient digestibility, caecal microbiota composition and volatile fatty acid (VFA) pattern was evaluated. Day-old Cobb broilers (n = 448) were allocated in four treatments for 6 weeks. Each treatment had four replicates (two per gender) of 28 broilers each. Depending on the type of addition per kg basal diet, treatments were C (no other addition), PL (108 colony forming units of probiotic), PH (109 colony forming units of probiotic) and A (2.5 mg avilamycin). Overall bodyweight gain was better (P = 0.002) in PL and PH than in the control (2082 g) by 8.7% and 7.5%, respectively, while treatment PL did not differ from A (2341 g), which showed the highest bodyweight gain. The ileal and total-tract apparent digestibility of DM and the apparent metabolisable energy content corrected for N improved linearly (P ≤ 0.05) with the probiotic level. Fluorescent in situ hybridisation analysis showed caecal Bifidobacterium levels to increase linearly (P = 0.006) with the probiotic level. Probiotic administration resulted in altered caecal VFA patterns compared with the control. Gender effects (P ≤ 0.05) were noted for caecal levels of C. histolyticum group, Bacteroides fragilis group and Streptococcus spp., while interactions (P ≤ 0.05) of treatment with gender were seen for Bifidobacterium and all VFA components, except for acetate. In conclusion, beneficial effects on bodyweight gain, DM digestibility, apparent metabolisable energy content corrected for N, caecal Bifidobacterium levels and VFA patterns were noted with both probiotic inclusion levels.

Comparative evaluation of probiotic and salinomycin effects on performance and coccidiosis control in broiler chickens

The annual financial loss to the poultry industry as a result of coccidiosis has been estimated at about US $3 billion. The objective of this study was to evaluate and compare the effects of probiotics and salinomycin as feed additives on performance and coccidiosis control in male broilers raised to 42 d of age. The study consisted of 360 Cobb male broiler chickens randomly allocated to 4 groups each with 3 replicates. Group 1: untreated, unchallenged negative control group (NC); group 2: untreated, challenged positive control group (PC); group 3: negative control supplemented with salinomycin 66 mg/kg, challenged group (Sal); and group 4: negative control supplemented with probiotics, challenged (Prob mix). On d 15, all birds (except group 1) were challenged with approximately 75,000, 25,000, and 75,000 of Eimeria acervulina, Eimeria maxima, and Eimeria tenella oocytes, respectively, that were mixed into the feed. Feed conversion ratio and mortality were recorded throughout the experiment. On d 21 and 42, intestinal lesions and litter conditions were scored. On d 7, 14, 21, 28, 35, and 42, oocyst counts were determined from 10 freshly collected fecal samples per pen. The results showed that mortality, litter, and lesion scores at d 21 and 42, and oocyst shedding at d 21 did not differ significantly between the Prob mix and the Sal groups. However on d 28, oocyst shedding was significantly lower in the Sal group than in the PC group but insignificantly lower than the Prob mix group. Body weights of the Prob mix group at d 42 were significantly lower than the Sal group; however, the feed conversion ratio values were similar between the 2 groups. The results of this study showed that probiotics supplementation could be considered as a potential strategy to control coccidiosis in broiler chickens.

Milk thistle extract and silymarin inhibit lipopolysaccharide induced lamellar separation of hoof explants in vitro

The pathogenesis of laminitis is not completely identified and the role of endotoxins (lipopolysaccharides, LPS) in this process remains unclear. Phytogenic substances, like milk thistle (MT) and silymarin, are known for their anti-inflammatory and antioxidant properties and might therefore have the potential to counteract endotoxin induced effects on the hoof lamellar tissue. The aim of our study was to investigate the influence of endotoxins on lamellar tissue integrity and to test if MT and silymarin are capable of inhibiting LPS-induced effects in an in vitro/ex vivo model. In preliminary tests, LPS neutralization efficiency of these phytogenics was determined in an in vitro neutralization assay. Furthermore, tissue explants gained from hooves of slaughter horses were tested for lamellar separation after incubation with different concentrations of LPS. By combined incubation of explants with LPS and either Polymyxin B (PMB; positive control), MT or silymarin, the influence of these substances on LPS-induced effects was assessed. In the in vitro neutralization assay, MT and silymarin reduced LPS concentrations by 64% and 75%, respectively, in comparison PMB reduced 98% of the LPS concentration. In hoof explants, LPS led to a concentration dependent separation. Accordantly, separation force was significantly decreased by 10 µg/mL LPS. PMB, MT and silymarin could significantly improve tissue integrity of explants incubated with 10 µg/mL LPS. This study showed that LPS had a negative influence on the structure of hoof explants in vitro. MT and silymarin reduced endotoxin activity and inhibited LPS-induced effects on the lamellar tissue. Hence, MT and silymarin might be used to support the prevention of laminitis and should be further evaluated for this application.

Evaluation of the endotoxin binding efficiency of clay minerals using the Limulus Amebocyte lysate test: an in vitro study

Endotoxins are part of the cell wall of Gram-negative bacteria. They are potent immune stimulators and can lead to death if present in high concentrations. Feed additives, which bind endotoxins in the gastrointestinal tract of animals, could help to prevent their negative impact. The objective of our study was to determine the potential of a bentonite (Bentonite 1), a sodium bentonite (Bentonite 2), a chemically treated smectite (Organoclay 1) and a modified attapulgite (Organoclay 2) to bind endotoxins in vitro. Polymyxin B served as positive control. The kinetic chromogenic Limulus Amebocyte lysate test was adapted to measure endotoxin activity. Firstly, a single sorption experiment (10 endotoxin units/mL (EU/mL)) was performed. Polymyxin B and organoclays showed 100% binding efficiency. Secondly, the adsorption efficiency of sorbents in aqueous solution with increasing endotoxin concentrations (2,450 – 51,700 EU/mL) was investigated. Organoclay 1 (0.1%) showed a good binding efficiency in aqueous solution (average 81%), whereas Bentonite 1 (0.1%) obtained a lower binding efficiency (21-54%). The following absorbent capacities were calculated in highest endotoxin concentration: 5.59 mg/g (Organoclay 1) > 3.97 mg/g (Polymyxin B) > 2.58mg/g (Organoclay 2) > 1.55 mg/g (Bentonite 1) > 1.23 mg/g (Bentonite 2). Thirdly, a sorption experiment in artificial intestinal fluid was conducted. Especially for organoclays, which are known to be unspecific adsorbents, the endotoxin binding capacity was significantly reduced. In contrast, Bentonite 1 showed comparable results in artificial intestinal fluid and aqueous solution. Based on the results of this in vitro study, the effect of promising clay minerals will be investigated in in vivo trials.

Mycotoxin occurrence in feed and feed raw materials worldwide: long-term analysis with special focus on Europe and Asia

During an 8-year period, 17 316 samples of feed and feed raw materials from all over the world were analysed for contamination with aflatoxins, ochratoxin A, zearalenone, deoxynivalenol and fumonisins. Overall, 72% of the samples tested positive for at least one mycotoxin and 38% were found to be co-contaminated. Mycotoxin concentrations were generally low and the majority of the samples were compliant with the most stringent EU guidance values or maximum levels for mycotoxins in feed. However, in their present state these regulations do not address co-contamination and associated risks. Long-term trends are difficult to establish as strong yearly variations were observed regarding mycotoxin prevalence and contamination levels. In some cases unusual weather conditions can be linked with high observed mycotoxin loads. An exception to this rule is South-East Asia, where a steady increase of aflatoxin prevalence has been observed. The percentage of aflatoxin-positive samples in this region rose from 32% in 2005 to 71% in 2011.

Global occurrence of mycotoxins in the food and feed chain: facts and figures

Mycotoxins are ubiquitously present in agricultural commodities, such as cereals and oil seeds. If ingested in sufficiently high concentrations, they exert severe toxic effects in humans and animals. In 2004, a survey programme was launched to assess the extent of mycotoxin contamination in feed and feed raw materials. Since then, over 19,000 samples have been analysed and more than 70,000 individual analyses have been conducted. While it is difficult to infer any long-term trends on a global level, the data confirm that high mycotoxin contamination is often linked to unusual weather. Overall, 72% of the samples contained detectable amounts of aflatoxins, fumonisins, deoxynivalenol, zearalenone or ochratoxin A. Co-contamination with two or more mycotoxins was detected in 38% of the samples. In most cases the concentrations were low enough to ensure compliance with EU guidance values or maximum levels. However, co-contaminated samples with concentrations below guidance and maximum values might still exert adverse effects due to synergistic interactions of the mycotoxins. Emerging mycotoxins and masked mycotoxins may also contribute to the overall toxicity of the feed and their presence is frequently detected with multi-mycotoxin LC-MS/MS. Since by-product feeds, such as distillers dried grain with solubles, often concentrate the mycotoxins of the original substrate, they contribute excessively to the overall contamination of feed rations and therefore need special attention. Regarding food the situation is quite similar: low level contamination is frequently observed in official controls but maximum levels are rarely exceeded in developed countries. As it is very difficult to remove mycotoxins from contaminated commodities, preventing them from accumulation in agricultural commodities is the most effective strategy to combat the problem. Preventive measures range from crop rotation and resistance breeding to inoculation with microbial antagonists. Nevertheless, excessive mycotoxin levels may occur despite all preventive measures. Therefore, continuous monitoring is essential and efficient detoxification strategies are needed to deal with such outbreaks.