Co-occurring mycotoxins in animal feeds

Mycotoxin contamination of feeds results in economic loss and transmission of toxins in the food chain. Animal feeds, the raw ingredients used in their manufacture, namely, maize, wheat, sunflower seeds, cottonseeds, bagasse, wheaten bran, gluten feed and pet foods from South Africa were surveyed for contaminating mycotoxin-producing fungi and their toxins: aflatoxins, fumonisins, zearalenone and ochratoxins. Toxins were extracted and analysed by high performance liquid chromatography and fluorometry. Twenty-one of the twenty-three samples were contaminated by Aspergillus flavus which co-occurred with A. parasiticus in two samples, A. tamarii in seven and Fusarium moniliforme in one. Rhizopus stolonifer, R. oryzae and yeast were also isolated. Aflatoxins were detected in seventeen samples, fumonisin in six and zearalenone in three. Aflatoxin levels ranged between 0.8 ± 0.2 and 156 ± 8 µg/kg (ppb), zearalenone between 100 ± 10.5 and 165 000 ± 200 µg/kg and fumonisin B1 between 15 ± 3.0 and 5 900 ± 40 µg/kg. Ochratoxins were not detected in any of the samples. In most countries worldwide, legislated levels for aflatoxins and patulin are 20 µg/kg and 50 µg/kg, respectively, for human foods. Fumonisins, zearalenone and other toxins are not legislated in most of the countries. Ten of the feeds contain toxin levels above legislated limits (for Canada and the USA) and guidelines set by other countries. The results of this study highlight the need for mycotoxin legislation in the animal feed industry