Fungi and natural incidence of selected mycotoxins in barley rootlets

Abstract

The storage of barley rootlets is increasingly employed to provide raw material for pig feeding in Brazil. Barley rootlets represent an important feedstuff for animal production due to their high levels of protein and fiber, and low price. However, poor management of raw materials during storage can result in fungal growth, the loss of nutritive substances and contamination by mycotoxins. The aims of this work were (1) to identify fungi associated with barley rootlets used as pig feedstuff raw material, and (2) to identify and quantify selected mycotoxins naturally produced by isolated mycotoxin-producing species in this substrate over a year. Samples were examined for fungal counts and genera distribution. Fumonisin B 1 and aflatoxin B 1 contamination were determined using high pressure liquid chromatography (HPLC). Barley rootlet samples were of low hygienic quality. Although a broad survey was undertaken, low fungal diversity was found. Fusarium verticillioides was the most prevalent species followed by Aspergillus flavus. Despite Aspergillus clavatus being widely associated with high-moisture sprouted grains including brewers’ grains, and causing toxicity to livestock, it was not detected in this work. Although pre-harvest contamination of the barley crop, as in the maize, could occur, the barley might support F. verticillioides/ Fusarium proliferatum growth when grain is remoistened during the germination and malting process and it might even continue during storage on pig farms. All samples were positive for fumonisin B 1 whereas aflatoxin B 1 contamination was not detected. It is important to point out the potential risk of fumonisin contamination in barley rootlets used as animal feed. Fusarium toxins are important not so much for their acute effects as for the chronic syndromes reported worldwide. The obtained results reveal the need for periodic monitoring of raw materials to avoid problems in animal production and hazards to animal and human health.