Concentration of mycotoxins and chemical composition of corn silage: A farm survey using infrared thermography

This work evaluated the chemical composition and mycotoxin incidence in corn silage from 5 Brazilian dairy-producing regions: Castro, in central-eastern Parana State (n = 32); Toledo, in southwestern Parana, (n = 20); southeastern Goias (n = 14); southern Minas Gerais (n = 23); and western Santa Catarina (n = 20). On each dairy farm, an infrared thermography camera was used to identify 3 sampling sites that exhibited the highest temperature, a moderate temperature, and the lowest temperature on the silo face, and 1 sample was collected from each site. The chemical composition and concentrations of mycotoxins were evaluated, including the levels of aflatoxins B-1, B-2, G(1), and G(2); zearalenone; ochratoxin A; deoxynivalenol; and fumonisins B-1 and B-2. The corn silage showed a highly variable chemical composition, containing, on average, 7.1 +/- 1.1%, 52.5 +/- 5.4%, and 65.2 +/- 3.6% crude protein, neutral detergent fiber, and total digestible nutrients, respectively. Mycotoxins were found in more than 91% of the samples, with zearalenone being the most prevalent (72.8%). All samples from the Castro region contained zearalenone at a high average concentration (334 +/- 374 mu g/kg), even in well-preserved silage. The incidence of aflatoxin B-1 was low (0.92%). Silage temperature and the presence of mycotoxins were not correlated; similarly, differences were not observed in the concentration or incidence of mycotoxins across silage locations with different temperatures. Infrared thermography is an accurate tool for identifying heat sites, but temperature cannot be used to predict the chemical composition or the incidence of mycotoxins that have been analyzed, within the silage. The pre-harvest phase of the ensiling process is most likely the main source of mycotoxins in silage.