Occurrence of deoxynivalenol (DON) and ochratoxin A (OTA) in dog foods

The commercially available dog food samples (29 dry foods and 11 wet foods) were analysed for deoxynivalenol (DON) and ochratoxin A (OTA) using ELISA. All (100%) dry foods were contaminated with DON with various amount of the toxin (22-1837 μg/kg). In wet food 3 samples were found to be positive for DON in the range of 95-170 μg/kg. There were a few samples contaminated with OTA: 3 samples in dry foods (7-40 μg/kg) and 2 samples in wet foods (45 and 115 μg/kg).     

A survey on the occurrence of mycotoxins in wheat and maize from western Romania

Samples of wheat (n = 25) and maize (n = 30) for animal consumption, collected in 1997 after harvest from western Romania, were analyzed by enzyme immunoassays for mycotoxin contamination. Toxins analyses included deoxynivalenol (DON), 3-acetylDON, 15- acetylDON, fusarenone X (FX), T-2 Toxin (T-2), diacetoxyscirpenol (DAS), zearalenone (ZEA), fumonisin B1 (FB1), aflatoxin B1 (AFB1), ochratoxin A (OA), and citrinin (CT). DON and acetylDONs were the major contaminants in wheat (100%) and maize (46%). Median values for DON, 3-acetylDON, and 15-acetylDON were 880 μg kg-1, 66 μg kg- 1, and 150 μg kg-1 in wheat, and 890 μg kg-1, 180 μg kg-1, and 620 μg kg- 1 in maize, respectively. Additionally, 3,15-diacetylDON was detected in some samples by HPLC-EIA analysis. All samples were negative for FX (<150 μg kg-1). T-2 was found in wheat (n = 6) and maize (n = 1) at levels between 13 and 63 μg kg- 1. DAS (2.6 μg kg-1) was found in one maize sample. ZEA occurred in all wheat and in four maize samples, median values were 10 μg kg-1 and 250 μg kg-1, respectively. One maize sample contained FB1 (140 μg kg-1). All samples were AFB1-negative (<4 μg kg-1). OA was found in one wheat sample (37 μg kg- 1), CT was found in one maize sample (580 μg kg- 1). This first reported natural occurrence of a range of mycotoxins in Romanian feeding stuff shows that DON and acetyl DONs may be present at levels which may affect animal production. This revised version was published online in June 2006 with corrections to the Cover Date.     

Natural multi-occurrence of mycotoxins in rice from Niger State,Nigeria

Twenty-one rice samples from field (ten), store (six) and market (five) from the traditional rice-growing areas of Niger State, Nigeria were analysed for aflatoxins (AFs), ochratoxin A (OTA), zearalenone (ZEA), deoxynivalenol (DON), fumonisin B₁ (FB₁) and B₂ (FB₂), and patulin (PAT) by thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) respectively. T-2 toxin was determined using TLC only. AFs were detected in all samples, at total AF concentrations of 28–372 μg/kg. OTA was found in 66.7% of the samples, also at high concentrations (134–341 μg/kg) that have to be considered as critical levels in aspects of nephrotoxicity. ZEA (53.4%), DON (23.8), FB₁ (14.3%) and FB₂ (4.8%) were also found in rice, although at relatively low levels. T-2 toxin was qualitatively detected by TLC in only one sample. Co-contamination with AFs, OTA, and ZEA was very common, and up to five mycotoxins were detected in a single sample. The high AF and OTA levels as found in rice in this study are regarded as unsafe, and multi-occurrences of mycotoxins in the rice samples with possible additive or synergistic toxic effects in consumers raise concern with respect to public health.     

Co-occurrence of mycotoxins in swine feed produced in Portugal

A total of 404 samples of commercial swine feed from Portugal feed mills were analysed by HPLC methods for the presence of mycotoxins: 277 samples of feed for fattening pigs were analysed for ochratoxin A (OTA), zearalenone (ZEA), and deoxynivalenol (DON), and 127 samples of feed for sows were analysed for ZEA and fumonisins (FB₁ + FB₂). Concerning feed for fattening pigs, 21 (7.6%) samples were positive for OTA, (2–6.8 μg/kg), 69 (24.9%) were positive for ZEA (5–73 μg/kg), and 47 (16.9%) were positive for DON (100–864 μg/kg). In feed for sows, the results showed 29.9% of positive samples for ZEA (5–57.7 μg/kg) and 8.7% positive samples for FB₁ and FB₂ (50–391.4 μg/kg). Co-occurrence of DON/ZEA was found most frequently, but simultaneous contamination with OTA/ZEA and OTA/DON was also found.     

Natural Occurrence of 16 Fusarium Toxins in Grains and Feedstuffs of Plant Origin from Germany

A total of 220 samples comprising cereals, cereal byproducts, corn plants and corn silage as well as non-grain based feedstuffs was randomly collected during 2000 and 2001 from sources located in Germany and analysed for 16 Fusarium toxins. The trichothecenes scirpentriol (SCIRP), 15-monoacetoxyscirpenol (MAS), diacetoxyscirpenol (DAS), T-2 tetraol, T-2 triol, HT-2 and T-2 toxin (HT-2, T-2), neosolaniol (NEO), deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-ADON), 15-acetyldeoxynivealenol (15-ADON), nivalenol (NIV) and fusarenon-X (FUS-X) were determined by gas chromatography/mass spectrometry. Zearalenone (ZEA) and α- and β-zearalenol (α- and β-ZOL) were analysed by high performance liquid chromatography with fluorescence and UV-detection. Detection limits ranged between 1 and 19 μg/kg. Out of 125 samples of a group consisting of wheat, oats, corn, corn byproducts, corn plants and corn silage only two wheat samples did not contain any of the toxins analysed. Based on 125 samples the incidences were at 2–11% for DAS, NEO, T-2 Triol, FUS-X, α- and β-ZOL, at 20–22% for SCIRP, MAS, T-2 tetraol and 3-ADON, at 44–74% for HT-2, T-2, 15-ADON, NIV and ZEA, and at 94% for DON. Mean levels of positive samples were between 6 and 758 μg/kg. Out of 95 samples of a group consisting of hay, lupines, peas, soya meal, rapeseed meal and other oilseed meals, 64 samples were toxin negative. DAS, T-2 triol, NEO and FUS-X were not detected in any sample. The incidences of DON and ZEA were at 14 and 23% respectively, those of the other toxins between 1–4%, mean levels of positive samples were between 5 and 95 μg/kg.     

Natural Occurrence of Mycotoxins in Staple Cereals from Ethiopia

The occurrence of mycotoxins in barley, sorghum, teff (Eragrostis tef) and wheat from Ethiopia has been studied. Samples were analyzed for aflatoxin B₁ (AFB1), ochratoxin A (OTA), deoxynivalenol (DON), nivalenol (NIV) and zearalenone (ZEN) using high performance liquid chromatography (HPLC) and for fumonisins (FUM) using enzyme linked immunosorbent assay (ELISA). AFB1 and OTA were detected in samples of all the four crops. AFB1 was detected in 8.8% of the 352 samples analyzed at concentrations ranging from trace to 26 μg kg⁻¹. OTA occurred in 24.3% of 321 samples at a mean concentration of 54.1 μg kg⁻¹ and a maximum of 2106 μg kg⁻¹. DON occurred in barley, sorghum and wheat at 40–2340 μg kg⁻¹ with an overall incidence of 48.8% among the 84 mainly ‘suspect’ samples analyzed; NIV was co-analyzed with DON and was detected at 40 μg kg⁻¹ in a wheat sample and at 50, 380, and 490 μg kg⁻¹ in three sorghum samples. FUM and ZEN occurred only in sorghum samples with low frequencies at concentrations reaching 2117 and 32 μg kg⁻¹, respectively. The analytical results indicate higher mycotoxin contamination in sorghum, which could be related to the widespread storage of sorghum grain in underground pits leading to elevated seed moisture contents. This is the first report on the occurrence of OTA in teff.     

Fusarium toxin contents of maize and maize products purchased in the years 2000 and 2001 in Germany

Samples (n=106) of maize and maize products were analysed for 13 trichothecene toxins and zearalenone (ZON). All 14 toxins examined were detected, although with varying frequency. Cooccurrence of two or more toxins was observed in 96% of samples. The toxins of the scirpenol group scirpentriol, 15-monoacetoxyscirpenol and diacetoxyscirpenol were detected in 14, 27 and 3% of the samples analysed, the toxins of the T-2 group T-2 toxin, HT-2 toxin, T-2 triol und T-2 tetraol were found in 33, 66, 2 and 7%. Toxin content was higher in feeds than in foods (semolina and flour). In food samples, the German regulatory level for DON (500 μg/kg) was not exceeded, three samples of maize flour contained ZON above the regulatory level (50 μg/kg). Presented at the 26^th Mykotoxin-Workshop in Herrching, Germany, May17–19, 2004     

Mycotoxins in horse feed

A total of 62 samples of commercial horse feed preparations (complementary feeds) containing cereal mixtures (“muesli” or mash, n = 39; pelleted feeds, n = 12), and plain horse feed grains (maize, n = 5; oats, n = 4; barley, n = 2) were purchased from 21 different producers/distributors from the German market. All samples were analysed by competitive enzyme immunoassays (EIA) for six different mycotoxins (mycotoxin groups). Analytes (detection limit, mean recovery) were: deoxynivalenol (DON, 10 μg/kg, 84%), zearalenone (ZEA, 5 μg/kg, 93%), fumonisin B₁ (FB₁, 2 μg/kg, 113%), T-2 toxin (T-2, 0.1 μg/kg, 71%), sum of T-2 + HT-2 toxin (T-2/HT2, 0.2 μg/kg, 97%), ochratoxin A (OTA, 0.2 μg/kg, 67%), and total ergot alkaloids (Generic Ergot Alkaloids “GEA”, 30 μg/kg, 132%). All samples contained DON (16–4,900 μg/kg, median 220 μg/kg), T-2/HT-2 (0.8–230 μg/kg, median 24 μg/kg), and T-2 (0.3–91 μg/kg, median 7 μg/kg). ZEA was detected in 98% of the samples (7–310 μg/kg, median 61 μg/kg). Most samples (94%) were positive for FB₁ (2–2,200 μg/kg, median 27 μg/kg). Ergot alkaloids were detected in 61% of samples (28–1,200 μg/kg, median 97 μg/kg), OTA was found in 42% of samples (0.2–4 μg/kg, median 0.35 μg/kg). The results demonstrate that a co-contamination with several mycotoxins is very common in commercial horse feed from the German market. The toxin concentrations were in most cases well below the levels which are usually considered as critical or even toxic. The highest mycotoxin concentrations were mostly found in single-grain cereal feed: the maximum values for DON and FB₁ were found in maize, the highest T-2/HT-2 toxin concentrations were found in oats, and the highest concentration of ergot alkaloids was found in barley. In composed feeds, no correlation between cereal composition and mycotoxin levels could be found.     

Single laboratory evaluation of a planar waveguide-based system for a simple simultaneous analysis of four mycotoxins in wheat

The accuracy and precision of a commercially available system based on an indirect competitive immunoassay and planar waveguide technology was evaluated for the analysis of deoxynivalenol (DON), ochratoxin A (OTA), zearalenone (ZEAR), and T-2 toxin in wheat. The system generally performed well at the tested concentrations that were close to the regulatory limits of DON and OTA in wheat. The mean percent recovery of OTA from certified and in-house reference materials ranged from 90 to 111 %, with a relative standard deviation of 8–16 % (at 4.2, 4.9, and 7.0 μg/kg). Mean percent recoveries of DON ranged from 75 to 103 %, with a relative standard deviation of 14–20 % (at 610, 940, and 1300 μg/kg). As analyte concentrations approached the lower limits of the working range of 3 μg/kg OTA and 400 μg/kg DON, the mean percent recoveries and relative standard deviation increased for both DON and OTA. A lack of reference materials precluded a thorough evaluation of the method for the analysis of ZEAR and T-2. The particular strength of the technology was that multiple mycotoxins were analyzed simultaneously.     

Study on biodegradation of some A- and B-trichothecenes and ochratoxin A by use of probiotic microorganisms

In vitro biodegradation experiments were done using some probiotic microorganisms. DifferentSaccharomyces cerevisiae, Lactobacilli andBacilli strains were tested for their ability to degrade Nivalenol (NIV), Deoxynivalenol (DON), Diacetoxyscirpenol (DAS), T2-Toxin and Ochratoxin A (OTA). The concentrations of selected mycotoxins were in the range of natural occurring toxin contaminations (1ppm for NIV and DON, 500ppb for DAS and T-2 and 50ppb for OTA). No alteration of concentrations could be registered for the tested trichothecenes. The best results could be achieved in experiments with OTA by up to 94% detoxification. Influence of toxins on colony forming unit of all tested microorganisms were recorded. Especially T-2 toxin and DAS have a slowing effect on growth of some strains.     

Effect of T- and B-lymphocyte mitogens on interactions between lymphocytes and macrophages.

The mitogenic response of murine T cells ² to Con A, S-Con A and PHA was found to be macrophage-dependent. Optimal mitogenic responses were obtained when macrophage-depleted T-cell populations were reconstituted with 5% normal peritoneal macro-phages. Studies were carried out to investigate the effect of T- and B-cell mitogens on in vitro physical interactions between murine lymphocytes and macrophages. This was done by determining the number of T- or B cells binding to macrophages in the absence and in the presence of T- and B cell mitogens, and comparing the results of these experiments with the induction of lymphocyte proliferation. Con A increased the binding of T cells to macrophages when used in mitogenic doses (1–5 μg/ml). Dose response experiments showed that the same dose of Con A which produced maximal mitogenic stimulation also induced the greatest number of T cells to bind to macrophages. Nonmitogenic doses of Con A (20–50 μg/ml) did not enhance the binding of T cells, while identical doses of S-Con A both induced T cell mitogenesis and increased the number of T cells bound to macrophages. Similar results were obtained with PHA. None of the B-cell mitogens tested (LPS, EPO 127 and LAgl) increased the binding of either T or B cells to macrophages. PWM, which is mitogenic for both T and B cells, increased the binding of T cells to macrophages, but not that of B cells. In brief, the four T-cell mitogens tested (Con A, S-Con A, PHA, and PWM) induced specific physical interactions between T cells and macrophages, while none of the B-cell mitogens had any effect on the physical interactions between either B or T cells and macrophages when used in mitogenic doses.     

Trichothecenes and Mycoflora in Wheat Harvested in Nine Locations in Buenos Aires Province, Argentina

A total of 120 freshly harvested wheat samples from the 2004 season in nine locations from Northern Buenos Aires Province, Argentina, were analysed for trichothecene natural occurrence and associated mycoflora, and for determining the influence of commonly used fungicide field treatment and the cultivar type on trichothecene contamination. The trichothecenes T-2 tetraol, T-2 triol, HT-2 and T-2 toxin (HT-2, T-2), diacetoxyscirpenol (DAS), nivalenol (NIV), deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-ADON) and 15-acetyldeoxynivalenol (15-ADON) were analysed by gas chromatography and electron capture detection. Detection limits ranged from 4 to 20 μg/kg. The isolation frequencies of species were calculated. Alternaria alternata, Fusarium graminearum, Fusarium poae and Fusarium semitectum were the predominant fungal species identified as endogenous mycoflora. The type of cultivar and the fungicide field treatment did not affect significantly the trichothecene contamination. The trichothecenes type A detected were HT-2 and T-2 triol toxins and the type B were DON, NIV and 3-ADON. Based on 120 samples the incidences were 21.7% for 3-ADON, 22.5% for HT-2, 27.5% for T-2 triol and 85% for DON. NIV was confirmed in one sample. Mean levels of trichothecene positive samples were between 7 and 2788 μg/kg.     

Zearalenone, deoxynivalenol and fumonisins in mixed-feed for laying hens

Fusarium toxins are secondary metabolites produced byfungi of these genera in many commodities under certain conditions. A study was carried out to investigate the co-occurrence of zearalenone (ZEN), deoxynivalenol (DON) and fumonisins (FB₁ and FB₂) in 52 samples of mixed-feed for poultry contaminated withFusarium verticillioides. The zearalenone and deoxynivalenol were checked using immunoaffinity column and the extraction of fumonisin was performed by strong anion exchange (SAX) solid phase column. Detection and quantification were determined by high performance liquid chromatography (HPLC). The limit of detection was 5 μg/kg for ZEN, 100 μg/kg for DON and 50 and 100 μg/kg for FB₁ and FB₂ respectively.Fusarium toxins were detected in 20 samples. Sixteen samples were positive for ZEN (30.7%) presenting levels that ranged from 7.4 μg/kg to 61.4 μg/kg (mean=27.0 μg/kg). 13.5% of the samples presented contaminations of DON, with levels ranging from 100.0 μg/kg to 253 μg/kg (mean=l18.07 μg/kg). FB₁ was detected in 19.2% of samples, with levels ranging from 50.0 μg/kg to 110.0 μg/kg (mean=73.6 μg/kg). FB2 was not detected in any sample. In positive samples simultaneously contamination with two or three mycotoxins were detected in 9 of them (17.3%).     

Occurrence of trichothecenes, zearalenone and ochratoxin A in cereals and mixed feed from central Lithuania

A total of 92 samples — 23 winter wheat, 12 summer barley, 5 oats and 52 mixed feed — were collected from a state factory in Kaunas, Lithuania and were analysed for the presence of trichothecenes, zearalenone (ZEN) and ochratoxin A (OA) using gas chromatography with electron capture detection and immunoaffinity column/high performance liquid chromatography with fluorescence and UV detections. Deoxynivalenol (DON), nivalenol (NIV), T-2 toxin and HT-2 toxin were detected at concentrations above 10 μg/kg in 68%, 48%, 38% and 8% of cereal samples, respectively, and in 98%, 88%, 12% and 8% of samples of mixed feed for swine and poultry. More than 10 μg/kg of zearalenone and ochratoxin A were found in 58% and 92% of the mixed feed samples, respectively. The highest concentrations of all analysed trichothecenes in Lithuanian mixed feed and cereal grains, with an exception of T-2 toxin in one oat lot and one sample of mixed feed and OA in two mixed feed samples, were lower than those reported as Lithuanian advisory or tolerance limits.     

T-2 and HT-2 toxin analysis in cereals and cereal products following IAC cleanup and determination via GC-ECD after derivatization

The authors present a new and sensitive method for the determination of T-2- und HT-2 Toxin in cereals and cereal products in the low ppb level. A representative part of the cereal sample is extracted with a mixture of methanol-water (90:10) and the extract is cleaned on the commercially available immunoaffinity column T-2test™ (IAC), eluted with methanol, derivatized by pentafluorpropionic anhydride (PFPA) and measured on a GC-ECD. The method has been successfully validated on wheat, rye and oats. The recovery rates with wheat and rye endowed on a level of 50 ppb and with 85 ppb naturally contaminated oats were 71–115% with a coefficient of variation of 5.7–19.5%. The detection limits of the method with a signal to noise level of 3:1 were 1.5–2.3 μg/kg for HT-2 and 1.1–1.7 μg/kg for T-2 toxin. Financial support: Federal Ministry of Food and Agriculture (part of the project 05HS 001 — Improvement and validation of type A trichothecene (T-2 toxin and HT-2 toxin) analysis and occurrence of these mycotoxins in food marketed in Germany)     

Reduction of Deoxynivalenol in Barley by Treatment with Aqueous Sodium Carbonate and Heat

Naturally contaminated lots of Canadian barley containing either 18.4 or 4.3 μg/g deoxynivalenol (DON) were heated at 80 °C, with small amounts of water or 1 M sodium carbonate solution to study the rate of DON reduction. Samples were heated in sealed polypropylene containers for periods of up to 8 days. In the 18.4 μg/g DON barley, rapid reductions were observed: with no solutions added, DON declined to 14.7 μg/g after 1 day, and to 4.9 μg/g after 8 days solely due to heat; with water at 10 mL/100 g barley, DON levels reached 3.7 μg/g after 8 days; with 1 M sodium carbonate solution added at 10 mL/100 g barley, DON declined to 4.7 μg/g after 1 day, and to 0.4 μg/g after 8 days; with 20 mL/100 g barley, DON declined to 1.4 μg/g after 1 day and to near-zero levels after 8 days. In the 4.3 μg/g DON barley, more gradual reductions were evident: with no solutions added, DON declined to 2.9 μg/g after 8 days solely due to heat; with water at 10 mL/100 g barley, DON levels reached 2.3 μg/g after 8 days; with 1 M sodium carbonate solution added at 10 mL/100 g barley, DON declined to 2.7 μg/g after 1 day, and to near-zero levels after 8 days; with 20 mL/100 g barley, DON declined to 1.4 μg/g after 1 day and to near-zero levels after 3, 5 and 8 days.     

Mycotoxins in several Polish food products in 2004–2005

In 2004–2005, samples of several selected Polish foods such as cereal products, nuts, dried fruits, coffee and culinary spices collected from Warsaw market and taken from food producers were analyzed on presence of aflatoxin B₁, B₂, G₁, G₂ (AF), ochratoxin A (OTA), zearalenone (ZEA) and deoxynivalenol (DON). After extraction and clean-up of extracts on immunoaffinity columns (IAC), mycotoxin analyses were carried out by HPLC using fluorescence and UV detectors. The concentrations of aflatoxins and ochratoxin A depending on the kind of sample ranged from 0.02 to 7.8 (one sample, of peanuts) and 0.02–11.9 μg/kg (one coffee sample), respectively. The levels of ZEA and DON were found to be below 50 °g/kg.     

Trichothecene-induced cytotoxicity on human cell lines

Trichothecene cytotoxicity of type A (T-2 toxin and HT-2 toxin), type B (deoxynivalenol, DON, and nivalenol, NIV), and type D (satratoxins G and H) compounds was determined comparatively by using eight permanent human cell lines (Hep-G2, A549, CaCo-2, HEp-2, A204, U937, RPMI 8226, and Jurkat). Viability of cells was measured by a water-soluble tetrazolium (WST-1) reagent cell proliferation assay assessing mitochondrial metabolic activity. Toxicity was expressed as the toxin concentration inhibiting 50% of cell viability (IC₅₀). Depending on the chemotype of the tested trichothecenes, relative cytotoxic activity differed by a factor of 100–1,000, and the corresponding IC₅₀ values were in the range from 2.2 nmol/l (satratoxin H on Jurkat and U937 cells) to 4,900 nmol/l (deoxynivalenol on HEp-2 cells). In contrast, the specific toxicity of each individual mycotoxin towards different cell lines was within remarkable close limits, and between-cell line differences were much smaller than previously reported. For the cell lines tested, IC₅₀ values were 4.4–10.8 nmol/l for T-2 toxin, 7.5–55.8 mol/l for HT-2 toxin, 600–4,900 nmol/l for DON, 300–2,600 nmol/l for NIV, and 2.2–18.3 nmol/l for satratoxins G/H. In addition, for the first time, the toxic activity of trichothecenes on primary cell culture of human endothelial cells (HUVEC) was tested. The susceptibility of this cell line was comparable to the other cell lines tested, with IC₅₀ values ranging from 16.5 nmol/l (T-2 toxin) to 4,500 nmol/l (DON). The results suggest that the current focus of cytotoxicological studies on trichothecenes on lymphoid cell lines may lead to an underestimate of their potential on other target cell systems.     

Mycotoxin production in a carbendazim-resistant strain of fusarium sporotrichioides

Mycelial yield and production of three trichothecenes, namely T-2 toxin, diacetoxyscirpenol (DAS) and neosolaniol (NEO) were compared in control (CS) and carbendazim-resistant strains (RS) ofFusarium sporotrichioides. Each strain was exposed to graded concentrations of carbendazim (0, 1, 2, and 4 μg/ml media) for 2, 5 and 7 days under shake-culture conditions at an incubation temperature of 25°C. Mycelial yield was significantly (P<0.001) affected by strain, carbendazim concentration and incubation time. The strain differences in mycelial mass at 2 days (P<0.05) became more pronounced at 5 and 7 days of incubation (P<0.001). However, mycelial growth differences between the two strains were greatest following exposure to carbendazim, with the effects becoming more divergent with time. Combined results for the three incubation times showed dose related effects in carbendazim inhibition of T-2 toxin production by CS isolates. In contrast, RS cultures exposed to the 2 μg/ml addition of carbendazim significantly increased T-2 toxin production (P<0.05 or better). At 1 and 4 μg/ml additions, T-2 toxin inhibition occurred but the effect was less marked than in the CS series. RS yielded more DAS than CS at 5 days (P<0.05) and at 7 days (P<0.01) of incubation. The major component of this strain difference arose from the effects of the 2 μg/ml addition of carbendazim (P<0.01). NEO production was also higher in RS than in CS, with the difference becoming progressively more pronounced from day 5 (P<0.05) to day 7 (P<0.01) of incubation. However, these differences reflected enhanced NEO output with carbendazim addition of 4 μg/ml (P<0.05) in day 5 extracts and of both 2 μg/ml (P<0.01) and 4 μg/ml additions (P<0.05) in day 7 samples. Moreover, the ratio of NEO to T-2 toxin production was affected by an interaction involving incubation time, strain and carbendazim dose (P<0.05 or better). On day 5, this ratio was greater in CS exposed to 2 μg/ml, but at 4 μg/ml, the ratio was higher in RS. It is concluded that carbendazim resistance induced genuine differences in the synthesis of T-2 toxin and NEO. It is suggested that the strain difference may reside in the conversion of NEO to T-2 toxin which may be sensitive to fungicide concentration. This would imply that carbendazim resistance induces changes in the terminal rather than initial phases of trichothecene biosynthesis.     

Mycotoxins in laboratory rodent feed

Twenty-one batches of fixed-formula rodent diets from three feed manufacturers were tested for the presence of five mycotoxins: deoxynivalenol (DON), nivalenol (NIV), HT-2 toxin, T-2 toxin and ochratoxin A (OTA). Five batches were also tested for the presence of zearalenone (ZEN) and six batches for aflatoxins. Detectable levels of DON (up to 298 microg/kg), NIV (up to 118 microg/kg), OTA (up to 3.1 microg/kg) or ZEN (up to 26.7 microg/kg) were found in samples from all manufacturers. Three batches contained two (DON or NIV and OTA or ZEN) and one batch contained three (DON, OTA and ZEN) different mycotoxins. Aflatoxins, T-2 and HT-2 were not detected in any of the batches. The concentrations of mycotoxins detected in the feed were low, but indicated that feed ingredients, probably the cereal ingredients, were contaminated by mycotoxins. Since mycotoxins are known to have toxic and/or immunosuppressive effects, non-contaminated ingredients should be used for production of laboratory animal feed. The results imply that an improved quality control of ingredients used for laboratory rodent feed should be implemented.