| Summary: | The product L-Threonine is a feed additive produced by fermentation with a genetically modified strain of Escherichia coli. L-Threonine is an essential amino acid for all animal species. It is commonly considered the second and third limiting amino acid in cereal-based diets for pigs and poultry, respectively. It is widely used in the feed industry to optimise dietary protein. The amino acid L-threonine itself is considered safe for the target animals, the consumer and the environment. However, the possible presence of the production strain and its recombinant DNA, including antibiotic resistance genes used in the genetic modification process, in the final product cannot be excluded. Consequently, the FEEDAP Panel cannot conclude on the safety of L-threonine produced by fermentation with such E. coli strain for the target animals, consumers and the environment. Regardless of the assessment of the genetic modification, the FEEDAP Panel has concerns regarding the safety of amino acids, including L-threonine, for target species when administered via water for drinking. From the results provided, it is concluded that there is no concern for users in respect of respiratory toxicity, or skin or eye irritancy. In the absence of any data on sensitisation, it is concluded that the product may have the potential to be a dermal sensitiser. The concerns regarding the safety of the genetic modification may also have implications for the safety of the user. The product L-threonine is an efficacious source of supplemented amino acid which helps to maintain or restore the adequate balance of dietary amino acids for all non-ruminant species. Supplemental L-threonine is degraded by ruminal microorganisms if not given in a protected form.
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