Survey of mycotoxin contamination in feedlot diets in Brazil

The objective of this survey was to identify mycotoxins and their concentrations in typical total mixed rations (TMR) used in Brazilian feedlots. The survey covered 30 Brazilian feedlots located in 5 major beef-producing states. Total mixed ration samples were collected on-site and sent to APTA (São Paulo, BR) to be lyophilized, milled, and subsequently sent to the 37+™ Analytical Services Laboratory (KY, USA) for analysis of mycotoxins. The evaluation of mycotoxins comprised 2 distinct steps: In a first step, the absolute quantification of 38 different mycotoxins was performed using a validated and ISO/IEC 17025:2005 accredited method by means of ultra-performance liquid chromatography electrospray ionization tandem mass spectrometry and involving isotopic dilution step and a data normalization process. In a second step, the mycotoxin concentrations were further interpreted according to known species specific sensitivities and normalized according to the principles of toxic equivalent factors, determining the risk equivalency quantities (REQ) expressed in ug/kg of AFB1-equivalent. Data were examined and descriptive statistics were obtained using the UNIVARIATE procedure of SAS (9.2). Several toxins were identified in TMR and their average concentrations determined, such as fumonisins at 2175 µg/kg, trichothecenes A at 69.5 µg/kg, trichothecenes B at 15.9 µg/kg, fusaric acid at 84.0 µg/kg, aflatoxins at 0.7 µg/kg and ergot at 1.83 µg/kg. The frequency of occurrence represented 97% for fumonisins, 80% for fusaric acid, 63% for trichothecenes A, 33% for ergot, 20% for trichothecenes B, and 10% for aflatoxins. This survey demonstrates that it is important to consider the combined occurrence of different types of mycotoxins in animal feed that are often neglected in other analytical approaches. Co-occurrences are important since mycotoxins could have an additive effect, potentially further increasing their negative impact. Therefore, in addition to identifying which mycotoxins are present in TMR and which levels, it is also important to estimate the risks associated with the presence of different types of mycotoxins. The maximum REQ found in the feedlots evaluated in this survey was 230 and the minimum REQ was 1 µg/kg AFB1-equivalent, an REQ of 50, 100 and 150 being considered low (67% of samples), intermediate (27%) and high (7%) risk for beef cattle. In conclusion, fumonisins are the mycotoxins found most frequently and at highest concentrations in TMR fed in Brazilian feedlots. Interestingly, fusaric acid has been reported for the first time in Brazilian feedlots in 80% of the samples investigated.