Background: Pyrrolizidine alkaloids are secondary plant metabolites with hepatotoxic effect in humans and several animal species. In recent studies, foods such as herbal teas and honey have been found to be contaminated with pyrrolizidine alkaloids.
Objectives: The aim of this study was to identify and assess pyrrolizidine alkaloids in compound feeds manufactured for horses and containing either alfalfa or a blend of herbs.
Methods: Forty-eight feed products for horses were included in the study. The feedstuffs were analysed for 28 selected pyrrolizidine alkaloids by liquid chromatography-mass spectrometry. The concentrations of the individual pyrrolizidine alkaloids were summed to calculate the total pyrrolizidine alkaloid content.
Results: In 7 of 48 samples, pyrrolizidine alkaloid concentrations were below the limit of quantification of 1-5 μg/kg. The median of 41 out of 48 samples was 58 μg/kg, and the 25 and 75th percentiles were 8 and 151 μg/kg. The highest observed pyrrolizidine alkaloid concentrations, 1306 and 1222 μg/kg, were found in two alfalfa-based feed products, followed by 836 μg/kg in an herb-containing feed product. Lycopsamine, seneciphylline, seneciphylline-N-oxide, senecionine and senecionine-N-oxide were the most frequently detected alkaloids.
Main limitations: Risk assessment was based on no-observed-adverse-effect-level for pyrrolizidine alkaloids in rats and humans. The specific susceptibility of horses to pyrrolizidine alkaloids remains unknown.
Conclusions: According to our risk assessment, pyrrolizidine alkaloid contamination should be limited to <90 μg/kg in equine compound feeds. We showed a high rate of pyrrolizidine alkaloids contamination in feed products for horses. In 43% of the analysed samples, pyrrolizidine alkaloid levels exceeded the calculated maximum tolerable levels. There is a need to introduce measures to reduce pyrrolizidine contamination in equine feedstuffs. The Summary is available in Portuguese - see Supporting Information.
Keywords: alfalfa; herbs; horse; liver; risk assessment; toxicity; undesirable substances.
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