Philippe Guerre

Effect of low dose of fumonisins on pig health: immune status, intestinal microbiota and sensitivity to Salmonella.

The objective of this study was to measure the effects of chronic exposure to fumonisins via the ingestion of feed containing naturally contaminated corn in growing pigs infected or not with Salmonella spp. This exposure to a moderate dietary concentration of fumonisins (11.8 ppm) was sufficient to induce a biological effect in pigs (Sa/So ratio), but no mortality or pathology was observed over 63 days of exposure. No mortality or related clinical signs, even in cases of inoculation with Salmonella (5 × 104 CFU), were observed either. Fumonisins, at these concentrations, did not affect the ability of lymphocytes to proliferate in the presence of mitogens, but after seven days post-inoculation they led to inhibition of the ability of specific Salmonella lymphocytes to proliferate following exposure to a specific Salmonella antigen. However, the ingestion of fumonisins had no impact on Salmonella translocation or seroconversion in inoculated pigs. The inoculation of Salmonella did not affect faecal microbiota profiles, but exposure to moderate concentrations of fumonisins transiently affected the digestive microbiota balance. In cases of co-infection with fumonisins and Salmonella, the microbiota profiles were rapidly and clearly modified as early as 48 h post-Salmonella inoculation. Therefore under these experimental conditions, exposure to an average concentration of fumonisins in naturally contaminated feed had no effect on pig health but did affect the digestive microbiota balance, with Salmonella exposure amplifying this phenomenon.

Sphinganine to sphingosine ratio and predictive biochemical markers of fumonisin B1 exposure in ducks

The kinetics of free sphinganine (Sa), sphinganine to sphingosine ratio (Sa/So), proteins, cholesterol, alanine aminotransferase (ALAT) and lactate dehydrogenase (LDH) were investigated in the course of fumonisin B1 (FB1) exposure in ducks (20 growing males divided into four groups of 5 receiving, respectively, a daily dose of 0, 5, 15 or 45 mg/kg FB1 via oral administration over 12 days). Descriptive statistics of these parameters were also studied in a large number of ducks not exposed to mycotoxins and free of known pathology. Although the toxin at the end of the treatment affected all the parameters investigated, only 2 days of treatment appeared necessary to increase free Sa concentrations in serum, whereas 6 days were necessary to detect a significant effect on Sa/So ratio. Significant differences between control and treated ducks were observed after 4 days of treatment for ALAT and LDH and after 6 and 8 days for cholesterol and proteins concentrations. The minimum doses of FB1 required to determine an effect were assessed using three different methods. This approach reveals that FB1 has greater effects when it is ingested at a low dose for a long time than when ingested at a high dose for a short time. Although the minimum toxic dose of FB1 in ducks remains to be determined, this result must be considered in the context of chronic exposure to the toxin, not only in avian populations.

Determination of Fumonisin B1 in animal tissues with immunoaffinity purification.

Immunoaffinity extraction combined with high-performance liquid chromatography (HPLC) with fluorescence detection was developed to determine Fumonisin B1 (FB1) in duck tissues. The method was linear over a concentration range of 0.013-0.250 microg of FB1/g of liver, kidney and muscle. The limit of quantification was 0.013 microg FB1/g in tissue. The mean percentage of extraction was 75% for liver and kidney and 53% for muscle. This method can be used in duck for the detection of FB1 contamination after exposure, the liver being the most contaminated tissue.

Toxicity of maize containing known levels of fumonisin B1 during force-feeding of ducks

The toxicity of maize containing known doses of fumonisin B1 (FB1) was investigated in mallard ducks during force-feeding. Seventy-five ducks at 12 wk of age were randomly divided into 3 groups of 25, and received control maize, naturally contaminated maize containing 20 mg/kg of FB1, or a mixture of control and contaminated maize (50/50, vol/vol). Force-feeding was performed during 12 d that correspond to a final average feed intake of approximately 10 kg of maize per duck. At the end of the study, 8% mortality was observed in ducks fed 20 mg of FB1/kg of feed, whereas no mortality occurred in the other groups. Liver weight, and plasma concentrations of protein, cholesterol, alanine aminotransferase (ALAT), and lactate dehydrogenase (LDH) were increased by force-feeding, whereas feed conversion ratio appeared decreased by the toxin. Microscopic examination of the liver showed that steatosis was mostly macrovacuolar in control ducks, whereas it was microvacuolar in ducks fed 20 mg of FB1/kg of feed. Free sphingolipid concentrations were measured in liver and plasma. Sphinganine (Sa) and sphinganine to sphingosine (Sa/So) ratio were increased in all treatment groups. These parameters were not affected by force-feeding and all individual values obtained in the treated ducks were higher than those obtained in control ducks. Our results suggest that free Sa level and Sa/So ratio can be used to reveal exposure of ducks to FB1 at doses of 10 mg/kg or greater in feed.

Ergot Alkaloids Produced by Endophytic Fungi of the Genus Epichloë

The development of fungal endophytes of the genus Epichloë in grasses results in the production of different groups of alkaloids, whose mechanism and biological spectrum of toxicity can differ considerably. Ergot alkaloids, when present in endophyte-infected tall fescue, are responsible for “fescue toxicosis” in livestock, whereas indole-diterpene alkaloids, when present in endophyte-infected ryegrass, are responsible for “ryegrass staggers”. In contrast, peramine and loline alkaloids are deterrent and/or toxic to insects. Other toxic effects in livestock associated with the consumption of endophyte-infected grass that contain ergot alkaloids include the “sleepy grass” and “drunken horse grass” diseases. Although ergovaline is the main ergopeptine alkaloid produced in endophyte-infected tall fescue and is recognized as responsible for fescue toxicosis, a number of questions still exist concerning the profile of alkaloid production in tall fescue and the worldwide distribution of tall fescue toxicosis. The purpose of this review is to present ergot alkaloids produced in endophyte-infected grass, the factors of variation of their level in plants, and the diseases observed in the mammalian species as relate to the profiles of alkaloid production. In the final section, interactions between ergot alkaloids and drug-metabolizing enzymes are presented as mechanisms that could contribute to toxicity.

Toxicokinetics of fumonisin B1 in turkey poults and tissue persistence after exposure to a diet containing the maximum European tolerance for fumonisins in avian feeds.

The kinetic of fumonisin B1 (FB1) after a single IV and oral dose, and FB1 persistence in tissue were investigated in turkey poults by HPLC after purification of samples on columns. After IV administration (single-dose: 10mg FB1/kg bw), serum concentration-time curves were best described by a three-compartment open model. Elimination half-life and mean residence time of FB1 were 85 and 52min, respectively. After oral administration (single-dose: 100mg FB1/kg bw) bioavailability was 3.2%; elimination half-life and mean residence time were 214 and 408min, respectively. Clearance of FB1 was 7.6 and 7.5ml/min/kg for IV and oral administration, respectively. Twenty-four hours after the administration of FB1 by the intravenous route, liver and kidney contained the highest levels of FB1 in tissues, level in muscle was low or below the limit of detection (LD, 13microg/kg). The persistence of FB1 in tissue was also studied after administration for 9 weeks of a feed that contained 5, 10 and 20mg FB1+FB2/kg diet. Eight hours after the last intake of 20mg FB1+FB2/kg feed (maximum recommended concentration of fumonisins established by the EU for avian feed), hepatic and renal FB1 concentrations were 119 and 22microg/kg, level in muscles was below the LD.

Tissue persistence of fumonisin B1 in ducks and after exposure to a diet containing the maximum European tolerance for fumonisins in avian feeds

Toxicity and persistence of fumonisin B1 (FB1) in liver, kidney and muscle were investigated in ducks fed 5, 10 and 20mg FB1+FB2/kg feed during force-feeding. Mortality and signs of toxicity were only obtained with 20mg/kg, whereas an increased Sa/So ratio was observed from 5mg/kg on. Persistence of FB1 was only found in liver (16 and 20 microg FB1/kg liver in ducks fed 10 and 20 mg FB1+FB2/kg feed, respectively). Toxicokinetic studies were conducted by the intravenous route (IV, single dose: 10mg FB1/kg body weight) and the oral route (single dose: 100mg FB1/kg body weight), in growing ducks and in ducks during force-feeding. After IV administration, serum concentration-time curves were described by a two-compartment open model. Elimination half-life and mean residence time of FB1 were 26 and 24 min, respectively, clearance was 19.3 ml/min/kg. After oral administration, bioavailability, elimination half-life, mean residence time and clearance varied during force-feeding and growth from 2-2.3%, 71-80 min, 200-188 min, 16.7-17 ml/min/kg, respectively. Taken together these results demonstrate that the risk of persistence of FB1 in ducks after force-feeding is very low, Sa/So being a good biomarker which increases before signs of toxicity and risk of persistence of FB1 in tissue (limit of detection 13 microg/kg).

Fusariotoxins in Avian Species: Toxicokinetics, Metabolism and Persistence in Tissues.

Fusariotoxins are mycotoxins produced by different species of the genus Fusarium whose occurrence and toxicity vary considerably. Despite the fact avian species are highly exposed to fusariotoxins, the avian species are considered as resistant to their toxic effects, partly because of low absorption and rapid elimination, thereby reducing the risk of persistence of residues in tissues destined for human consumption. This review focuses on the main fusariotoxins deoxynivalenol, T-2 and HT-2 toxins, zearalenone and fumonisin B1 and B2. The key parameters used in the toxicokinetic studies are presented along with the factors responsible for their variations. Then, each toxin is analyzed separately. Results of studies conducted with radiolabelled toxins are compared with the more recent data obtained with HPLC/MS-MS detection. The metabolic pathways of deoxynivalenol, T-2 toxin, and zearalenone are described, with attention paid to the differences among the avian species. Although no metabolite of fumonisins has been reported in avian species, some differences in toxicokinetics have been observed. All the data reviewed suggest that the toxicokinetics of fusariotoxins in avian species differs from those in mammals, and that variations among the avian species themselves should be assessed.

Endophyte infection of tall fescue and the impact of climatic factors on ergovaline concentrations in field crops cultivated in southern France.

Tall fescue (Lolium arundinaceum) infected by Epichloe coenophiala contains ergot alkaloids responsible for fescue toxicosis in Australia, New Zealand, and the United States, with only a few cases occurring in Europe. The detection of Epichloe in 166 L. arundinaceum collected in southern France revealed that 60% were infected, 51% being high ergovaline producers. The ergovaline level in endophyte-infected tall fescue Kentucky 31 was monitored during 3 years in various parts of the plant. Maturation of plants, recorded according to the BBCH scale, appeared to be the main factor for estimating the risk of toxicity. Ergovaline levels of ≥300 μg/kg dry matter were obtained at the end of spring, the beginning of autumn, and mid-winter. Positive correlation between ergovaline level and cumulative degree-d was observed, whereas rainfall had no effect. These results suggest that the lack of fescue toxicosis observed in France cannot be explained by the lack of ergovaline in tall fescue.

Worldwide Mycotoxins Exposure in Pig and Poultry Feed Formulations

The purpose of this review is to present information about raw materials that can be used in pig and poultry diets and the factors responsible for variations in their mycotoxin contents. The levels of mycotoxins in pig and poultry feeds are calculated based on mycotoxin contamination levels of the raw materials with different diet formulations, to highlight the important role the stage of production and the raw materials used can have on mycotoxins levels in diets. Our analysis focuses on mycotoxins for which maximum tolerated levels or regulatory guidelines exist, and for which sufficient contamination data are available. Raw materials used in feed formulation vary considerably depending on the species of animal, and the stage of production. Mycotoxins are secondary fungal metabolites whose frequency and levels also vary considerably depending on the raw materials used and on the geographic location where they were produced. Although several reviews of existing data and of the literature on worldwide mycotoxin contamination of food and feed are available, the impact of the different raw materials used on feed formulation has not been widely studied.