Affection of coarse fodders by toxigenic Fusarium fungi

Lack of information about the distribution of toxigenic Fusarium fungi in hay and cereal straw which is used for bedding and feeding animals inhibits preventive measures against animal toxicoses. Multiple combined fusariotoxin contamination of hay was recently established during advanced mycotoxicological survey of commercially used batches from the livestock farms in European Russia (G.P. Kononenko, A.A. Burkin, 2014). The aim of this work was to study the species complex of fusaric fungi in fodders from Chelyabinsk, Bryansk and Moscow regions of Russia in different years and to evaluate the toxin-producing capacity of their populations. All 60 samples of hay and straw from Chelyabinsk region (1992) were colonized by fusaric fungi of 6 species - F. sporotrichioides Sherb, F. avenaceum (Corda ex Fr.) Sacc., F. poae (Peck) Wr., F. tricinctum (Corda) Sacc., F. culmorum (W.G. Smith) Sacc. and F. sambucinum Fuckel. Unidentified Fusarium species were detected in hay of bromegrass, galega, annual (a mixture of wheat, oats and peas) and perennial grasses, and a complex of these fungi was found in rye straw. The majority of samples (90 %) contained F. sporotrichioides (a single species, or this species along with other, but F. sporotrichioides mostly predominated). Of 19 samples of the hay and straw harvested in the Bryansk region (2011), 16 were infected by Fusarium fungi belonging to the same 8 species. F. sporotrichioides was found in 11 samples and prevailed, and the other 7 detected species were less frequent - F. tricinctum (4 samples), F. equiseti (Corda) Sacc. (3 samples), F. poae (2 samples), F. solani (Mart.) Sacc. (2 samples), F. culmorum, F. graminearum Schw. and F. semitectum Berk. et Rav. (each in one sample). In fodders from Moscow region (2013) Fusarium fungi were found in 171 samples of 239 tested (71.5 %) and the affection was often very high. Isolated fungi belonged to the same 8 species as in other regions mentioned. By the frequency of occurrence they were ranged in the following order: F. sporotrichioides, F. tricinctum, F. avenaceum, F. poae, F. culmorum, F. graminearum, F. semitectum, F. solani, with F. sporotrichioides found in 85.7 % of the samples. In addition, we identified three isolates as F. cerealis (Cooke) Sacc., F. sambucinum and F. torulosum (Berk. & M. A. Curtis). Fungal cultures grown on rice grain substrate at 23 °С for 7 days were first used to test the toxin production. F. sporotrichioides was shown to possess 100 % potential for T-2 toxin (122-1078 μg/g) and diacetoxyscirpenol (0.7-20 μg/g) production, F. culmorum, F. graminearum, F. cerealis, F. torulosum - for deoxynivalenol and zearalenone production, and in two F. semitectum isolates the level of zearalenone was high. Extensive distribution of F. sporotrichioides producing T-2 toxin and its highly toxic analog diacetoxyscirpenol, necessitates special attention to control the level of these trichothecenes at harvesting and storage of roughage. Specific features of toxin-production of other Fusarium species and hay contamination with deoxynivalenol and zearalenone are discussed.