The aim of this study was to evaluate the occurrence of several fungal metabolites, including mycotoxins in natural grasses (Poaceae) intended for grazing cattle. A total number of 72 and 77 different metabolites were detected on 106 and 69 grass samples collected during 2011 and 2014, respectively. A total of 60 metabolites were found across both years. Among the few mycotoxins considered toxic for ruminants, no samples of natural grasses were contaminated with aflatoxins, ochratoxin A, ergot alkaloids, and gliotoxin, among others. However, we were able to detect important metabolites (toxic to ruminants) such as type A trichothecenes, mainly T-2 toxin and HT-2 toxin (up to 5000 µg/kg each), and zearalenone (up to 2000 µg/kg), all at very high frequencies and levels. Other fungal metabolites that were found to be prevalent were other Fusarium metabolites like beauvericin, equisetin and aurofusarin, metabolites produced by Alternaria spp., sterigmatocystin and its precursors and anthrachinone derivatives. It is important to point out that the profile of common metabolites was shared during both years of sampling, and also that the occurrence of important metabolites is not a sporadic event. Considering that this area of temperate grassland is used for grazing cattle all year long due to the richness in palatable grasses (Poaceae), the present work represents a starting point for further studies on the occurrence of multi-mycotoxins in natural grasses in order to have a complete picture of the extent of cattle exposure. Also, the present study shows that the presence of zeranol in urine of beef cattle may not be a consequence of illegal use of this banned substance, but the product of the natural occurrence of zearalenone and α-zearalenol in natural grasses intended for cattle feeding.

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The objectives of the present study were to determine the combined effects of chitosan and water activity (aW) on growth and mycotoxin production in situ on the two most important Fusarium species (F. proliferatum and F. verticillioides) present on maize, and on F. graminearum, the main pathogen causing Fusarium head blight on wheat. Results showed that low-molecular-weight chitosan with more than 70% deacetylation at the lowest dose used (0.5 mg/g) was able to reduce deoxynivalenol (DON) and fumonisin (FBs) production on irradiated maize and wheat grains. Growth rates of F. graminearum also decreased at the lowest chitosan dose used (0.5 mg/g), while F. verticillioides and F. proliferatum growth rates were reduced at 0.98 aW at the highest chitosan dose used (2 mg/g). Since mycotoxins are unavoidable contaminants in food and feed chains, their presence needs to be reduced in order to minimize their effects on human and animal health and to diminish the annual market loss through rejected maize and wheat; in this scenario, pre- and post-harvest use of chitosan could be an important alternative.

Fusarium armeniacum has been found as a saprophyte on natural grasses devoted to cattle feed in Argentina. This species has been reported as highly toxigenic due to the production of trichothecenes type A, but the information available about its toxigenic profile is incomplete. Thus, the aim of the present study was to determine the toxigenic ability of 50 F. armeniacum isolates recovered from natural grasses using a multitoxin method based on LC-MS/MS. In addition, morphological identification of 15 selected isolates was confirmed by sequencing the translation elongation factor 1α. Out of the 327 metabolites analysed, only 10 were detected: T-2 toxin (T-2), T-2 triol, T-2 tetraol, HT-2 toxin (HT-2), diacetoxyscirpenol (DAS), monoacetoxyscirpenol (MAS), neosolaniol (NEO), aurofusarin (AUF), beauvericin (BEA) and zearalenone (ZEA). The most common group of mycotoxins produced by the isolates on rice under laboratory conditions was trichothecenes type A, and some minor Fusarium mycotoxins, such as BEA and AUF. Some isolates were also able to produce ZEA. Among the trichothecene type A, HT-2, T-2, NEO were clearly synthesised at the highest levels and frequency, followed by DAS and MAS. HT-2, T-2, NEO and DAS production was detected in 48 (96%), 47 (94%), 47 (94%) and 38 (76%) isolates, respectively. The ability of F. armeniacum, to produce ZEA and AUF has been demonstrated here for the first time. Given the new information provided about the toxigenic profile of this species, commonly associated with natural grasses in Argentina, the threat to animal health posed by this fungus should not be underestimated.