Preliminary survey of zearalenone and other mycotoxins in Argentinean natural pastures intended for cattle feed

RAMIREZ M L; CHIACCHIERA S.M.; SULYOK M; NICEHA M.J.; PALACIOS S. A.; GONZALEZ PEREYRA M.L.; KRSKA R; CHULZE S.N.

Roterdam

Conferencia; 7th Conference of The World Mycotoxin Forum y XIII the IUPAC International Symposium on Mycotoxins and Phycotoxins; 2012

Meat production in Argentina is based on the exploitation of natural sources with traditional extensive grazing. Fusarium toxins such as zearalenone and trichothecenes are common mycotoxins found in cereal grains and are important causes of mycotoxicosis. They are not commonly associated with forage-based feeding systems. However, Fusarium toxins have been found to be of significance in grazing animals. Of particular concern to the Argentinean livestock industry is that zearalenone (ZEA) is chemically similar to the growth promoting á-zearalanol (zeranol), which is banned in Argentina as well as in the EU. In the last two years zeranol has been detected in bovine urine during a routine analysis of beef cattle farms as part of a national residues control plan by the central competent authority, National Service for Health and Food Quality (SENASA). Several reports from New Zealand and Northern Ireland have shown that zeranol might occur naturally in urine and bile from sheep and cattle following metabolism of the mycotoxins zearalenone and á-zearalenol that can contaminate animal feedstuffs. Thus, the finding of zeranol in an animal might, on its own, be insufficient proof that malicious abuse of zeranol has occurred. A pilot survey was undertaken to ascertain if zearalenone was present in natural pastures in two beef cattle farms in which a positive urine sample from cattle have been previously found. Forty samples of natural grasses were collected during winter 2011 (July) from selected paddock of two beef cattle farms located in Chaco province, Argentina. Samples were analysed using an LC-MS/MS based multimycotoxin method that does not use any clean-up. Recovery experiments (i.e. spiking 5 individual samples at two concentration levels) confirmed the applicability of the method to the matrix as 74% of the investigated analytes exhibited apparent recoveries between 60 and 140%. The analysis revealed the presence of ZEA in 39 out of 40 samples with a median concentration of 141 µg/kg (range between 1.2 and 2120 µg/kg), and partial co-occurrence of á and â-zearalenol. The evaluation of the impact of the presence of ZEA in the samples was complicated by the co- occurrence of T-2 Toxin (n=25, median concentration of positive samples 140 µg/kg) and HT-2 Toxin (n=18, median concentration of positive samples 374 µg/kg) that were found in high frequency. Other fungal metabolites that were found to be prevalent were beauvericin, equisetin and aurofusarin, metabolites produced by Alternaria spp., sterigmatocystin and its precursors and anthrachinone derivatives such as emodin, chrysophanol and skyrin. This is the first report of the presence of fungal metabolites including ZEA and its derivatives on natural pastures intended for cattle feed in Argentina.