Progression of mycotoxin and nutrient concentrations in wheat after inoculation with Fusarium culmorum

The objective of this study was to follow the mycotoxin formation and changes in nutrient composition of wheat (cv. Ritmo) artificially inoculated with Fusarium culmorum. From anthesis until harvest, samples were taken once a week from the inoculated and control plots. The investigations were focused on monitoring the progression of the contamination of the wheat kernels with deoxynivalenol (DON) and zearalenone (ZON). Both the uncontaminated control kernels and the contaminated kernels were examined also for the presence of zearalenone-4-beta-D-glucopyranoside and several trichothecenes at harvest. Furthermore, the impact of the Fusarium inoculation on some nutrients as starch, crude protein, amino acid composition, crude ash, non starch polysaccharides (NSP) as well as viscosity and thousand seed weight (TSW) was examined. Also proteolytic and amylolytic activity as well as the NSP-degrading enzyme activities of inoculated and control samples were analysed at the time of harvest. DON was detected in higher concentrations and in earlier stages, while ZON was found later and in smaller amounts. On average 7.79 mg/kg DM of DON and 100 microg/kg DM of ZON were found in the inoculated kernels at the time of harvest. Neither in the contaminated nor in the control samples glucose conjugates of ZON (Zearalenone-4-beta-D-glucopyranoside) were detected. Moreover, the infection with Fusarium culmorum had pronounced effects on some quality parameters. The crude protein content of the inoculated kernels showed significantly higher values over the whole period compared to the control kernels. The protein content of the inoculated kernels amounted 13.9% DM at harvest, while only a concentration of 12.5% DM was detected in the control samples. Similarly, in almost all stages of development the crude ash content of inoculated samples was higher than in control samples. These distinct differences in kernel composition resulted possibly from the changes of the thousand seed weight. In the present work the grain harvested from the control plots showed a significantly higher TSW (24.2 g) as compared to their inoculated counterparts (15.5 g). Despite lower extract viscosity of inoculated samples at time of harvest, the content of soluble NSP of inoculated plots was higher than in control samples at the same time. Moreover, inoculation resulted in markedly increased activities of protease, amylase and several NSP-degrading enzyme activities. This would suggest that the cell wall penetrating properties of the fungus itself and/or that the fungus induced alterations of the metabolic activity of the embryo or other constituents of the wheat kernel could be responsible.     

Progression of the mycotoxin and nutrient concentration in wheat after inoculation with<Emphasis Type="Italic">Fusarium culmorum</Emphasis>

The aim of the study was to follow the mycotoxin formation and the changes in nutrient composition of wheat artificially inoculated withFusarium cuimorum. From anthesis until harvest, samples were taken once a week from the inoculated and control plots. The investigations were focused on the progression of the contamination of the wheat with deoxyni-valenol (DON) and zearalenone (ZON). Furthermore, the impact of the Fusarium inoculation on the quality parameters starch, crude protein, crude ash, viscosity, non starch polysaccharides (NSP) and thousand seed weight was examined. Deoxynivalenol was detected in higher concentrations and in earlier stages, while zearalenone was found later and in smaller amounts. Moreover, the infection withFusarium cuimorum had pronounced effects on some quality parameters.     

Influence of a Fusarium culmorum inoculation of wheat on the progression of mycotoxin accumulation, ingredient concentrations and ruminal in sacco dry matter degradation of wheat residues

The Fusarium head blight (FHB)-susceptible winter wheat cv. Ritmo was inoculated with spores of Fusarium culmorum at the beginning of full blossom. Samples of whole wheat plants were taken once weekly from anthesis until harvest and subsequently fractionated into straw, glumes and spindles, which were examined for deoxynivalenol (DON) and zearalenone (ZON). Additionally, the content of crude protein (CP) and non-starch polysaccharides (NSP) was scrutinized. Synthesis of the Fusarium toxins DON and ZON generally differed in terms of date of formation and concentration. Final mean DON concentrations of 37.5, 28.1 and 5.0 mg/kg DM were measured in glumes, spindles and straw, respectively, at the time of harvest. At this time, maximal mean ZON concentrations of 587, 396 and 275 microg/kg DM in spindles, glumes and straw, respectively, were determined. Moreover, Fusarium infected wheat residues contained higher CP but lower NSP contents at the last three sampling dates. In addition, collective samples of wheat straw and chaff were taken to investigate the effect of the Fusarium contamination on their in sacco DM degradation in dairy cows. Samples were analysed for mycotoxins and selected quality parameters. The dried and milled collective samples of straw and chaff were weighed into nylon bags and subjected to ruminal incubation for 4, 8, 16, 24, 48, 72, 96 and 120 h in two dairy cows equipped with a permanent rumen cannula. Marked differences in level of mycotoxin contamination as well as in ingredient composition between the variants of straw and chaff were detected. Moreover, after 120 h rumen incubation the in sacco DM degradation of inoculated straw and chaff were lower compared to the accordant controls. The soluble fraction was increased in inoculated samples, whereas a diminishment in the potentially degradable but insoluble fraction was more pronounced. Thereby, a decrease in the potential degradability was obtained for inoculated straw and even if less pronounced for chaff compared to the non inoculated corresponding controls. In conclusion, infection with F. culmorum of wheat involves an increased risk of mycotoxin contamination in straw. Also, a Fusarium infection may have an impact on chemical composition and may result in Fusarium growth-related modifications of host cell wall components.     

Effects of Field Application of Tebuconazole on Yield, Yield Components and the Mycotoxin Content of Fusarium-infected Wheat Grain

Winter wheat cultivar Basalt was artificially inoculated with Fusarium culmorum at the end of anthesis and treated with the systemic fungicide tebuconazole (Folicur^®) a few days before and/or after inoculation. Check plots remained uninoculated and unsprayed. Head infections, yield, yield components and the percentage of Fusarium‐ infected kernels were determined. Artificial Fusarium inoculation lowered yield significantly by 24.2‐45.0%. Any fungicide treatment saved yield, thousand grain weight and kernel numbers per head. Pre‐infectional application of tebuconazole was superior to application carried out post‐infection. Moreover, the fungicide controlled deoxynivalenol (DON) synthesis in the field to a considerable extent, and enabled good control of Fusarium head blight, glume blotch and the percentage of Fusarium‐infected kernels. The levels of Fusarium kernel infection after harvest clearly reflected the DON content of w heat grain.     

A study of the correlation between the amount of deoxynivalenol in grain of wheat and triticale and percentage of<Emphasis Type="Italic">Fusarium</Emphasis> damaged kernels

The correlation between the amount of deoxynivalenol (DON) and the percentage ofFusarium damaged kernels (FDK) in samples of wheat and triticale was studied.Samples of naturally infected wheat grain, collected in 1986, 1987 and 1988 and of triticale collected in 1986 were used.Additionally, artificial inoculated wheat samples (10 genotypes inoculated with 3F. Culmorum strains of weak, medium and severe pathogenicity and samples of 10 triticale genotypes inoculated withF. culmorum. andF. graminearun) were studied. Using statistical methods (the variance analysis, method of least significant difference (LSD), orthogonal contrast (OC) and minimum within groups sum of squares criterion (MSSC)), the samples were divided into two groups with respect to the attribute DON/FDK.To the first group belong samples of wheat and triticale, of which the heads were artificially inoculated with severely pathogenic strainsF. culmorum. In the samples of this group the amount of DON in kernels damaged withFusarium increased by 0,46 mg/kg per 1% of FDK.In the second group, consisting of naturally infected samples and samples from artificially inoculated heads the amount of DON increased 0,30 mg DON/kg per 1% of FDK.The equation for the calculation of approximated amount of DON in farm and commercial lots of wheat and triticale after examination of percentage of FDK is given.     

Progression of deoxynivalenol and zearalenone concentrations in straw of wheat infected artificially withFusarium culmorum

This investigation aimed at the progression of the contamination of theFusarium toxins deoxynivalenol (DON) and zearalenone (ZON) within the fractions straw, glumes and spindles from non-inoculated andFusarium-inoculated wheat. TheFusarium head blight (FHB)-susceptible wheat cultivar Ritmo was cultivated after the pre-crop maize and artificially infected withFusarium culmorum. Samples of whole wheat plants were taken once a week from anthesis until harvest and fractionated into straw, glumes and spindles. Samples were examined for deoxynivalenol and zearalenone and quantitatively determined by high performance liquid chromatography (HPLC) with diode-array detection (DAD) and fluorescence detection, respectively. Additionally, the impact of theFusarium inoculation on the crude protein content was scrutinised. Differences in the formation of deoxynivalenol and zearalenone with respect to date and concentration are shown by this trial. Deoxynivalenol was produced in higher concentrations and at earlier stages, whereas zearalenone was formed later and in smaller amounts. Furthermore, a rise of the deoxynivalenol concentration up to a maximum during the growing season, followed by a sudden decline at later stages until harvest, was observed. ThisFusarium infection resulted in an increased crude protein content in all of the three fractions.     

<Emphasis Type="Italic">Fusarium</Emphasis> mycotoxins in conventionally and organically grown grain from Thuringia/Germany

Thefusarium mycotoxins deoxynivalenol (DON) and zearalenone (ZON) were determined in conventionally and organically grown grain harvested 1998 in Thuringia/Germany. A total of 196 wheat samples and 69 rye samples was analysed.In this year with heavy rainfalls during the summer months, high concentrations offusarium mycotoxins were typical in grain grown in Germany, as the DON concentrations found here. DON concentrations in conventionally grown wheat were found to be significantly higher than in organically grown wheat. 69% of the conventionally grown wheat were tested positive, containing a mean concentration of 1540 µg/kg DM. In 54% of the organically grown wheat samples DON was detected with a mean value of 760 µg/kg DM. DON concentration in rye and ZON concentration in wheat showed similar tendencies.The different cultivars of conventionally grown wheat showed large differences in DON contamination.     

Fusarium species and their mycotoxins in infected corn in Italy

Surveys of corn (infected plants and commercial kernels) forFusarium species and their mycotoxins were carried out on samples collected all over Italy and from some European and mediterranean countries.Investigations on samples of corn stalk and ear rot standing in the field, mainly collected in southern Italy, proved to be contaminated with zearalenone (ZON), zearalenols (ZOL), and deoxynivalenol (DON). TheFusarium species most frequently isolated, and their recorded toxigenic capability (in parentheses), were:F. moniliforme;F. culmorum (ZON, ZOL, DON, 3AcDON);F. equiseti (ZON, ZOL); andF. proliferatum (MF). Along with these species,F. graminearum group 2 (ZON, DON and/or 3AcDON or 15AcDON);F. chlamydosporum;F. acuminatum (type-A trichothecene derivatives); andF. semitectum were often found to be associated.F. heterosporum (ZON, ZOL);F. solani;F. crookwellense (ZON, ZOL, FUS, NIV);F. oxysporum (MF);F. avenaceum (MF);F. sporotrichioides (T-2 toxin and derivatives); andF. poae (DAS, MAS) were occasionally isolated.     

Effects of long-term storage on Fusarium toxin concentrations in wheat - sources of error of the analytical results

The concentrations of the Fusarium toxins deoxynivalenol (DON) and zearalenone (ZON) of a heavily contaminated wheat grain batch were followed over a period of 1 year by taking samples 15 times every 28 days. The air temperature and relative humidity at the top of the wheat batch ranged between 7 and 22°C and 44 and 55%, respectively, and corresponded to a variation in the moisture content of the wheat grain between 11.5 and 12.3%. None of these fluctuations were related to ZON and DON concentrations, which varied between 0.46 and 0.66 and 15.0 and 19.5 mg/kg DM. Therefore, the data were used to analyse the error sources for the analytical results. It was found that the variance proportions due to sampling and sample preparation plus analysis were not similar for DON and ZON. The variance proportion due to sampling was found to be 0.62 for ZON, which corresponded to a variance proportion of 0.38 due to sample preparation plus analysis. In contrast, the latter variance proportion for DON was estimated to be 1.0 and consequently completely superimposed the sampling error. It is concluded that long-term storage of contaminated wheat grain does not affect the concentrations of DON and ZON considering the measured fluctuations in ambient temperature, relative humidity and moisture content of the grain. Therefore, no degradation of DON and ZON occurred during the storage of wheat for a period of one year under ambient conditions. The effects of sampling and sample preparation plus analysis on the final analytical results are different for DON and ZON and require further consideration.     

Susceptibility of Barley Cultivars and Lines to Fusarium Infection and Mycotoxin Accumulation in Kernels

Heads of 12 barley genotypes (8 cultivars and 4 lines) were inoculated with conidial suspension of the following single isolates: F. culmorum no. 3, F. graminearum no. 122 and F. sporotrichioides no. ATCC 62 360. The number of kernels per head. 1000 Kernel weight and yield have been calculated for each genotype. Seed samples collected at harvest were analysed for each genotype. Seed samples collected at harvest were analysed for several trichothecene mycotoxins and zearalenone.The mycotoxin concentrations (mg/kg) in barley kernels inoculated with F. graminearum were as follows. deoxynivalenol (DON) 0.1 to 5.4 (av. 2.3). 3-acetyldeoxy-nivalenol (3-AcDON) 0.0–0.2 (av. 0.1), 15-acetyldeoxynivalenol (15-AcDON) 0.0–0.7 (av.0.2), nivalenol (NIV) 0.0–0.8 (av. 0.3). zearalenone (ZEA) 0.0–0.1 (av. 0.0); F. culmorum: DON 0.6 to 12.0 (av. 5.3), 3-AcDON 0.1 to 1.0 (av. 0.6). 15-AcDON nd. NIV 0.1–0.7 (av. 0.3). ZEA 0.1–0.5 (av. 0.2). F. sporotrichioides T-2 toxin 2.4–13.9 (av. 6.0), HT-2-toxin 0.1–0.8 (av.0.3) and neosolaniol 0.2–1.5 (av.0.7).     

Characterisation of<Emphasis Type="Italic">fusarium graminearum</Emphasis> and<Emphasis Type="Italic">F. culmorum</Emphasis> isolates by mycotoxin production and aggressiveness to wheat

A total of 27Fusarium culmorum isolates from Germany and 41F. graminearum isolates from Kenya were investigated for aggressiveness and mycotoxin production on wheat ears. In addition, ergosterol content of the kernels from ears inoculated withF. graminearum was determined and theF. culmorum isolates were tested for mycotoxin productionin vitro. For both pathogens, isolates markedly differed in aggressiveness. 59% and 37% of theF. culmorum isolates produced NIV and DON, respectively,in vivo andin vitro. The DON-producing isolates also produced 3-acDONin vitro. The more aggressive isolates produced mainly DON while the less aggressive isolates produced mainly NIV. 12% and 85% of theF. graminearum isolates produced NIV and DON, respectively. The highly aggressive isolates produced higher amounts of DON, aggressiveness being highly correlated to DON content in the kernels. NIV-producing isolates were less aggressive. Ergosterol content of kernels was moderately correlated to aggressiveness but highly correlated to DON content. Disease severity was associated with kernel weight reduction.     

The occurrence of culmorin and hydroxy-culmorins in cereals

Forty-five samples from 1988–1995 of naturally contaminated grain, barley, wheat and oats, three samples of mixed feed, and 16 samples of grain artificially inoculated with Fusarium culmorum during the flowering stage were analysed for deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-acetyl-DON), culmorin and hydroxy-culmorins. These compounds are secondary metabolites produced by the fungal species F. culmorum and F. graminearum. Acetonitrile-water extract of the samples was purified on a Mycosep^TM#225 column, derivetized using pentafluoropropionic anhydride (PFPA) and analysed by gas chromatography-mass spectrometry (GC-MS). The amount of each of culmorin, 5-, 12-, 14 and 15-hydroxy-culmorin and one unknown hydroxy-culmorin were determined relative to the amount of DON plus 3-acetyl DON for each sample. The ratio between the total amount of culmorin compounds and the DON compounds ranged from 0.14 to 1.07 in the samples. This study shows that there is a strong correlation between the amount of DON present in the grain and the amount of culmorin and hydroxy-culmorins present. The ratio of each of the culmorin compounds relative to the amount of DON compounds were in the same range in the grain artificially inoculated by F. culmorum as found in an earlier study for F. culmorum strains cultivated on rice, while the hydroxy-culmorin profile in the naturally contaminated grain was more similar to what was found for the F. graminearum cultures in the same study [1]. These results indicate that F. graminearum may be a relatively important source for DON in grain also in relatively cold areas. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of long-term storage on Fusarium toxin concentrations in wheat--sources of error of the analytical results

The concentrations of the Fusarium toxins deoxynivalenol (DON) and zearalenone (ZON) of a heavily contaminated wheat grain batch were followed over a period of 1 year by taking samples 15 times every 28 days. The air temperature and relative humidity at the top of the wheat batch ranged between 7 and 22 degrees C and 44 and 55%, respectively, and corresponded to a variation in the moisture content of the wheat grain between 11.5 and 12.3%. None of these fluctuations were related to ZON and DON concentrations, which varied between 0.46 and 0.66 and 15.0 and 19.5 mg/kg DM. Therefore, the data were used to analyse the error sources for the analytical results. It was found that the variance proportions due to sampling and sample preparation plus analysis were not similar for DON and ZON. The variance proportion due to sampling was found to be 0.62 for ZON, which corresponded to a variance proportion of 0.38 due to sample preparation plus analysis. In contrast, the latter variance proportion for DON was estimated to be 1.0 and consequently completely superimposed the sampling error. It is concluded that long-term storage of contaminated wheat grain does not affect the concentrations of DON and ZON considering the measured fluctuations in ambient temperature, relative humidity and moisture content of the grain. Therefore, no degradation of DON and ZON occurred during the storage of wheat for a period of one year under ambient conditions. The effects of sampling and sample preparation plus analysis on the final analytical results are different for DON and ZON and require further consideration.     

Production of trichothecene mycotoxins byFusarium graminearum andFusarium culmorum on barley and wheat

Wheat cultivars (Stoa, MN87150, SuMai-3, YMI-6, Wheaton) and barley cultivars (Robust, Excel, Chevron, M69) were inoculated in the field with isolates ofFusarium graminearum andF. culmorum. The diseased (Fusarium head blight) kernels were analyzed for deoxynivalenol (DON), 15-acetyldeoxynivalenol (15-ADON) and nivalenol (NIV).F. culmorum produced all three trichothecenes on all cultivars tested whereasF. graminearum only produced DON and 15-ADON. There was no well defined correlation between DON production in the host and resistance although the data tended to favor SuMai-3 as having definitive resistance to bothF. graminearum andF. culmorum.Minnesota Agricultural Experiment Station, Paper No. 20 279.     

Influence of localities and winter wheat cultivars on deoxynivalenol accumulation and disease damage by <Emphasis Type="Italic">Fusarium culmorum</Emphasis>

Toxin B — trichothecene deoxynivalenol (DON) is the most frequent Fusarium mycotoxin in Fusarium head blight (FHB) disease produced by Fusarium fungi. Thirty-one samples of naturally cultivated winter wheat were collected from different localities in Slovakia and evaluated for DON content, and after an artificial inoculation twelve of winter wheat cultivars were evaluated for FHB, fusarium damaged kernels (FDK) and DON content (resistance Type I and II) during two years. Plants were inoculated at anthesis with a conidial suspension of Fusarium culmorum (W. G. Smith) Sacc. The highest mean contents of DON 1.641 ppm were found in produced potato region (PPR) and 1.654 ppm in produced sugar beet region (PSBR). A positive correlation was found between DON content and rainfall, and a negative correlation was found between content of DON and temperature. Lower positive correlations were found between the contents of DON in 2003 and 2004 in the resistance Type I and Type II in twelve artificially infected cultivars. The significant positive correlations in content of DON were found between resistance Type I and Type II in the years 2003 and 2004. The lowest content of DON was found in the cultivars Alka, Malyska and the highest one in the cultivars Vanda and Boka. The positive correlation between the content of DON and FDK (in %) in head (average 2003 and 2004 years) from artificially infected and analysed cultivars was statistically significant in both resistances Type I and Type II.     

Effects of method of straw disposal and depth of cultivation on populations of Fusarium spp. in soil and on brown foot rot in continuous winter wheat

Soil samples (0–10 cm depth) taken from plots of continuous winter wheat at intervals between January 1993 and July 1996 were dilution-plated on PCNB agar to identify and enumerate colony-forming units (cfus) of Fusarium spp. Cfus of the main wheat pathogen, F. culmorum, were more numerous in soil from plots that were shallow-cultivated to 10 cm after each harvest than in those that were ploughed. They were also usually more numerous in plots in which straw had been chopped and incorporated (by shallow cultivation or ploughing) than in those in which straw had been burnt. Increasing amounts of straw tended to increase the number of cfus. Deeper sampling (15–25 cm) showed that ploughing resulted in a more even, but diluted, distribution of cfus down the soil profile. Populations of some commonly found species that are not pathogenic on wheat {F. oxysporum, F. equiseti, F. flocciferum and F. merismoides) were sometimes also affected by straw disposal or cultivation treatments. Alternative methods of estimating population densities (baiting soil with wheat kernels or wheat seedlings, or plating-out straw fragments) showed generally similar effects of treatments on populations of F. culmorum; the relative merits of the methods are considered. Large differences in population densities of all species occurred within and between seasons. The smallest populations were found in January 1995 but, in the case of F. culmorum, they increased to relatively large numbers in July 1995. The summer of 1995 was warm and dry and especially favourable for development of fusarium foot rot. Severe disease occurred only in this year and was less frequent after ploughing than after tine-cultivation but more frequent after straw burning than after straw incorporation. The implications of these observations for understanding the role of propagules of F. culmorum in soil as inoculum for foot rot are discussed.     

Analysis of Fusarium causing dermal toxicosis in marram grass planters

In the European coastal dunes, marram grass (Ammophila arenaria) is planted in order to control sand erosion. In the years 1986 to 1991, workers on the Wadden islands in the Netherlands planting marram grass showed lesions of skin and mucous membranes, suggesting a toxic reaction. Fusarium culmorum dominated the mycoflora of those marram grass culms that were used for planting. This plant material had been cut and stored for more than one week in the open. The Fusarium toxin deoxynivalenol (DON) was detected in the suspect marram grass culms. Isolated F. culmorum strains were able to produce DON in vitro in liquid culture as well as in experimentally inoculated wheat heads. Pathogenicity tests, toxin test as well as RAPD analysis showed that the F. culmorum strains were not specialized for marram grass but may form part of the West-European F. culmorum population infecting cereals and grasses. Storage on old sand-dunes with plant debris may have led to the high occurrence of F. culmorum and contamination with DON. Marram grass culms should be obtained from young plantings on dunes on the seaward slopes and cut culms should not be stored.     

The Effect of Nitrogen Fertilization on Fusarium Head Blight Development and Deoxynivalenol Contamination in Wheat

The impact of nitrogen (N) fertilization on the development of Fusarium head blight (FHB) in wheat and the resulting deoxynivalenol (DON) contamination in the kernels was studied. In a first experiment, the disease was assessed on two locations under natural infection pressure. Five different types of nitrogen fertilizer (both organic and mineral) were investigated, each applied at five input rates from 0 to 160 kg N/ha. With all fertilizers, a significant increase of disease intensity was observed with increasing N input, while the type of N fertilizer had poor or no effects on FHB. Depending on the fertilizer used, the percentage of diseased spikelets increased from 2.2% at zero N rate up to 6.6% at 160 kg N input per hectare. In a second series of trials, three spring wheat varieties including one Durum wheat line were artificially inoculated with a Fusarium graminearum and a F. culmorum strain, known producers of DON. A mineral N fertilizer was applied at five input levels from 0 to 160 kg N/ha. A significant increase in FHB intensity and DON contamination in the grain was observed with increasing N from 0 to 80 kg/ha. At higher input rates, relevant in contemporary crop husbandry, disease intensity and toxin contamination remained at constant levels. It is concluded that adaptation of N fertilization represents no relevant tool in managing FHB in practical wheat cultivation.     

Fusarium species complex and mycotoxins in grain maize from maize hybrid trials and from grower's fields

Aims: To quantify and to compare the occurrence of Fusarium species in maize kernels and stalk pieces, to analyse mycotoxins in kernels and maize crop residues, to evaluate two approaches to obtain kernel samples and to compare two methods for mycotoxin analyses. Methods and Results: The occurrence of Fusarium species in maize kernels and stalk pieces from a three‐year maize hybrid trial and 12 kernel samples from grower’s fields was assessed. Nine to 16 different Fusarium species were detected in maize kernels and stalks. In kernels, F. graminearum, F. verticillioides and F. proliferatum were the most prevalent species whereas in stalks, they were F. equiseti, F. proliferatum and F. verticillioides. In 2006, 68% of the kernel samples exceeded the recommended limit for pig feed for deoxynivalenol (DON) and 42% for zearalenone (ZON), respectively. Similarly, 75% of the samples from grower’s fields exceeded the limits for DON and 50% for ZON. In maize crop residues, toxin concentrations ranged from 2·6 to 15·3 mg kg^?1 for DON and from 0·7 to 7·4 mg kg^?1 for ZON. Both approaches to obtain maize kernel samples were valid, and a strong correlation between mycotoxin analysis using ELISA and LC‐MS/MS was found. Conclusions: The contamination of maize kernels, stalk pieces and remaining crop residues with various mycotoxins could pose a risk not only to animal health but also to the environment. With the hand‐picked sample, the entire Fusarium complex can be estimated, whereas combine harvested samples are more representative for the mycotoxin contents in harvested goods. Significance and Impact of the Study: This is the first multi‐year study investigating mycotoxin contamination in maize kernels as well as in crop residues. The results indicate a high need to identify cropping factors influencing the infection of maize by Fusarium species to establish recommendations for growers.     

On the effects ofFusarium-contaminated wheat and the feed intake level on ruminal fermentation and toxin-turnover of cows

The aim of the study was to examine the effects of dry matter intake level and the feeding ofFusarium-contaminated wheat on the toxin-turnover and ruminal fermentation of dairy cows. Fourteen dairy cows equipped with ruminal and duodenal cannulae were used. All animals were fed the same diet, only the daily feed amounts were adjusted to the current performance stage of the cow. On a dry matter basis, the diet consisted of 60% concentrate including 55% wheat (Fusarium-contaminated wheat [Mycotoxin period] or control wheat [Control period]). Each cow was fed with both the contaminated and the control wheat. TheFusarium-contamination of the wheat significantly decreased the flow of undegraded protein at the duodenum with increased intakes of organic matter. The duodenal flow of microbial protein and the activities of aspartate aminotransferase (ASAT), glutamate dehydrogenase (GLDH) and gamma glutamyl transferase (γ-GT) in the serum were not affected by dietary treatment, but increased with feed intake. The duodenal flow of deoxynivalenol (DON) and de-epoxy DON related to DON intake ranged between 12 and 77% when theFusarium-contaminated wheat was fed. DON was almost completely metabolized to de-epoxy DON independent of the feed intake level. The zearalenone (ZON) flow at the duodenum increased moderately with increasing ZON/feed intake.