Agronomic Factors Influencing the Scale of Fusarium Mycotoxin Contamination of Oats

Seven agronomic factors (crop season, farming system, harvest date, moisture, county, oat variety, and previous crop) were recorded for 202 oat crops grown across Ireland, and samples were analysed by LC-MS/MS for four major Fusarium mycotoxins: deoxynivalenol (DON), zearalenone (ZEN), T-2 toxin and HT-2 toxin. Type A trichothecenes were present in 62% of crops, with 7.4% exceeding European regulatory limits. DON (6.4%) and ZEN (9.9%) occurrences were relatively infrequent, though one and three samples were measured over their set limits, respectively. Overall, the type of farming system and the previous crop were the main factors identified as significantly influencing mycotoxin prevalence or concentration. Particularly, the adherence to an organic farming system and growing oats after a previous crop of grass were found to decrease contamination by type A trichothecenes. These are important findings and may provide valuable insights for many other types of cereal crops as Europe moves towards a much greater organic-based food system.

Agronomic Factors Influencing the Scale of Fusarium Mycotoxin Contamination of Oats

Seven agronomic factors (crop season, farming system, harvest date, moisture, county, oat variety, and previous crop) were recorded for 202 oat crops grown across Ireland, and samples were analysed by LC-MS/MS for four major Fusarium mycotoxins: deoxynivalenol (DON), zearalenone (ZEN), T-2 toxin and HT-2 toxin. Type A trichothecenes were present in 62% of crops, with 7.4% exceeding European regulatory limits. DON (6.4%) and ZEN (9.9%) occurrences were rela-tively infrequent, though one and three samples were measured over their set limits respectively. Overall, the type of farming system and the previous crop were the main factors identified to significantly influence mycotoxin prevalence or concentration. Particularly, adherence to an organic farming system and growing oats after a previous crop of grass were found to decrease contamination by type A trichothecenes. These are important findings and may provide valuable insights for many other types of cereals crops as Europe moves towards a much greater organic based food system.

70 Occurrence of Mycotoxins in 2020 US Corn Silage and Dairy Total Mixed Rations

Mycotoxins are fungal metabolites which have been identified in many feed ingredients and ruminants have an increased risk of exposure due to the complex nature of their diets. Despite varying degrees of natural detoxification in the rumen, cattle health, productivity, and reproduction can be compromised by mycotoxins. This study investigated mycotoxin occurrence and contamination levels in 2020 U.S. corn silage and dairy total mixed ration (TMR) samples. Samples were screened via LC-MS/MS for six major mycotoxin groups including: aflatoxins, type A trichothecenes (A-Trich), type B trichothecenes (B-Trich), fumonisins (FUM), zearalenone (ZEN), and ochratoxin A. Information was collected with each submission including state of origin and whether or not clinical health or performance concerns were present. Contamination levels were analyzed using the GLIMMIX procedure (SAS 9.4, Cary, NC) to investigate the interaction of clinical concern (yes/no) and harvest year. No interaction was statistically significant for each of the toxin groups, so main effects of harvest year are presented in Table 1. Type B trichothecenes have been identified most frequently in 2020 corn silage. Although not often detected, A-Trich occurrence has increased ten percentage points from 2019 crop year. Among 236 TMR samples analyzed, B-Trich have been detected in a high percentage of samples. Mean contamination levels (parts per billion, ppb) are presented on a dry matter basis and within each data set were similar in 2020 compared to 2019 for respective toxin groups. Preliminary survey results indicate B-Trich occur frequently in both U.S. corn silage and TMR samples. Despite less frequent detection, other mycotoxin groups do occur including ZEN, FUM, and A-Trich, so the potential risk from toxin interactions due to co-contamination should be considered.

Naturally Occurring Fusarium Species and Mycotoxins in Oat Grains from Manitoba, Canada

Fusarium head blight (FHB) can lead to dramatic yield losses and mycotoxin contamination in small grain cereals in Canada. To assess the extent and severity of FHB in oat, samples collected from 168 commercial oat fields in the province of Manitoba, Canada, during 2016–2018 were analyzed for the occurrence of Fusarium head blight and associated mycotoxins. Through morphological and molecular analysis, F. poae was found to be the predominant Fusarium species affecting oat, followed by F. graminearum, F. sporotrichioides, F. avenaceum, and F. culmorum. Deoxynivalenol (DON) and nivalenol (NIV), type B trichothecenes, were the two most abundant Fusarium mycotoxins detected in oat. Beauvericin (BEA) was also frequently detected, though at lower concentrations. Close clustering of F. poae and NIV/BEA, F. graminearum and DON, and F. sporotrichioides and HT2/T2 (type A trichothecenes) was detected in the principal component analysis. Sampling location and crop rotation significantly impacted the concentrations of Fusarium mycotoxins in oat. A phylogenetic analysis of 95 F. poae strains from Manitoba was conducted using the concatenated nucleotide sequences of Tef-1α, Tri1, and Tri8 genes. The results indicated that all F. poae strains belong to a monophyletic lineage. Four subgroups of F. poae strains were identified; however, no correlations were observed between the grouping of F. poae strains and sample locations/crop rotations.

Contamination of wheat, barley and maize seeds with toxigenic Fusarium species and their mycotoxins in Tunisia

Background Fusarium is a worldwide distributed fungal genus. It includes different species pathogenic to cereals among others crops. Some of these species can also produce toxic compounds towards animals and humans. Objective In this work, occurrence of fumonisins B1+B2, zearalenone, type A trichothecenes (T-2 and HT-2 toxins) and type B trichothecenes (deoxynivalenol and nivalenol) was studied in 65 samples of stored and freshly harvested wheat, barley and maize collected in Tunisia. Methods Mycotoxins analyses were performed by using gas chromatography for type B trichothecenes and high-performance liquid chromatography for other mycotoxins. Obtained results were compared with the presence of mycotoxigenic species considered responsible for their synthesis by using species-specific polymerase chain reaction (PCR). Results Fumonisins occurred in 20.83% of wheat, 40% of barley, and 57.14% of maize samples, at levels exceeding European limits and suggesting a risk in Tunisian cereals, especially maize. Zearalenone, deoxynivalenol, nivalenol and T-2+HT-2 toxins were detected at lower values in only wheat and barley samples. PCR protocols showed the predominance of F. verticillioides especially in maize, and occurrence of F. equiseti and F. graminearum in wheat and barley, and F. proliferatum in only 2 maize samples. A very consistent correlation was found between the detection of F. verticillioides and the contamination by fumonisins, as well as between the presence of F. graminearum and the contamination by zearalenone, deoxynivalenol and nivalenol in the analyzed cereals. Conclusions Consequently, the detection of Fusarium species with the current polymerase chain reaction assays strategy in wheat, barley and maize grains may be considered predictive of their potential mycotoxin risk in these matrices.

Phylogenetic diversity, trichothecene potential, and pathogenicity within Fusarium sambucinum species complex

The Fusarium sambucinum species complex (FSAMSC) is one of the most taxonomically challenging groups of fusaria, comprising prominent mycotoxigenic plant pathogens and other species with various lifestyles. Among toxins produced by members of the FSAMSC, trichothecenes pose the most significant threat to public health. Herein a global collection of 171 strains, originating from diverse hosts or substrates, were selected to represent FSAMSC diversity. This strain collection was used to assess their species diversity, evaluate their potential to produce trichothecenes, and cause disease on wheat. Maximum likelihood and Bayesian analyses of a combined 3-gene dataset used to infer evolutionary relationships revealed that the 171 strains originally received as 48 species represent 74 genealogically exclusive phylogenetically distinct species distributed among six strongly supported clades: Brachygibbosum, Graminearum, Longipes, Novel, Sambucinum, and Sporotrichioides. Most of the strains produced trichothecenes in vitro but varied in type, indicating that the six clades correspond to type A, type B, or both types of trichothecene-producing lineages. Furthermore, five strains representing two putative novel species within the Sambucinum Clade produced two newly discovered type A trichothecenes, 15-keto NX-2 and 15-keto NX-3. Strains of the two putatively novel species together with members of the Graminearum Clade were aggressive toward wheat when tested for pathogenicity on heads of the susceptible cultivar Apogee. In planta, the Graminearum Clade strains produced nivalenol or deoxynivalenol and the aggressive Sambucinum Clade strains synthesized NX-3 and 15-keto NX-3. Other strains within the Brachygibbosum, Longipes, Novel, Sambucinum, and Sporotrichioides Clades were nonpathogenic or could infect the inoculated floret without spreading within the head. Moreover, most of these strains did not produce any toxin in the inoculated spikelets. These data highlight aggressiveness toward wheat appears to be influenced by the type of toxin produced and that it is not limited to members of the Graminearum Clade.

60 Occurrence of Mycotoxins in 2019 US Corn-based Feed Ingredients

Mycotoxins are secondary fungal metabolites that are detrimental to animal health and productivity. This study investigated occurrence and contamination levels of mycotoxins in the 2019 US corn harvest, including corn grain and corn byproduct feed ingredients (distillers dried grains, gluten feed, etc.). Corn samples from the 2019 harvest and corn DDGS and other byproducts from October 2019 through April 2020 were screened via the LC-MS/MS technique for the presence of six major mycotoxin groups: aflatoxins, type A trichothecenes, type B trichothecenes (B-Trich), fumonisins (FUM), zearalenone (ZEN) and ochratoxin A. Parameters of the main toxins found were compared to the two prior harvest years using the Kruskal-Wallis Test (Prism7, GraphPad, La Jolla, CA) and are presented in Table 1. Mean toxin count per sample in corn grain was similar in 2019 as 2018, with just over two toxins per sample. Mean B-Trich level (parts per billion, ppb) was elevated in 2019 from 2017. Fumonisin contamination increased in 2019 compared to 2017, and prevalence was similar to 2018. Zearalenone contamination and prevalence were similar in 2019 compared to 2018 levels. Co-contamination in corn byproduct feeds was steady, averaging nearly three toxins per sample. Mean B-Trich contamination was higher than the 2017 crop, and FUM contamination was higher in 2019 than 2017 and 2018. Zearalenone levels in 2019 byproducts are the highest seen in the past three years. Preliminary results of the 2019 corn-based feed ingredients survey suggest mycotoxin occurrence and contamination levels are approaching those observed in the challenging 2018 crop. Furthermore, there are continued concerns for co-contamination and greater ZEN contamination that may impose negative effects on growth, health and reproductive performance in ruminants.

67 Occurrence of Mycotoxins in Forage-Based Feeds from US and Canada

Mycotoxins are secondary fungal metabolites that contaminate a variety of feedstuffs and are detrimental to animal health and productivity. The risk of broad-spectrum mycotoxin exposure is elevated for ruminants due to the complexity of their diets. This study investigated the occurrence and contamination levels of mycotoxins in forage-based feeds including corn silage, haylage (including various cuttings of multiple forage sources), and straw samples from across the US and Canada. Samples were screened for the six major mycotoxin groups: aflatoxins, type A trichothecenes, type B trichothecenes (B-Trich), fumonisins (FUM), zearalenone (ZEN), and ochratoxin A via LC-MS/MS technique. Samples submitted for clinical health or performance concerns were excluded from the data set. The B-Trich occurred most frequently (95% positive) among 92 corn silage samples harvested in 2019 followed by ZEN (34%) and FUM (9%). Mean contamination levels (parts per billion, ppb) on dry matter basis were 2,788 ppb, 456 ppb, and 194 ppb, respectively. Only 4% of silage samples were below the limit of detection (LOD) for all mycotoxins evaluated. Among 20 haylage samples from 2019 crop year, B-Trich were the most frequently detected, with 50% of samples positive at a mean concentration of 3,222 ppb. Twenty-one 2019 straw samples were submitted for analysis, with 100% testing positive for some level of B-Trich (mean 2,001 ppb) and 81% ZEN positive with an average of 640 ppb. Seventy-one percent of straw samples were positive for both B-Trich and ZEN. Preliminary mycotoxin survey results from US and Canada suggest B-Trich and ZEN are the most frequently occurring major mycotoxins in 2019 forage-based feed samples. Based on the frequency and levels of mycotoxin contamination identified in the current data set, continued analysis of forage-based feeds is warranted as mycotoxins pose a potential risk to the health, performance, and reproductive success of ruminants.