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J Anim Physiol Anim Nutr (Berl). 2015 Feb;99(1):73-78. doi: 10.1111/jpn.12208. Epub 2014 Jul 12.

Presence and content of kynurenic acid in animal feed.

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Department of Surgery and Surgical Nursing, Medical University, Lublin, Poland.
Department of Toxicology, Institute of Agricultural Medicine, Lublin, Poland.
Department of Microbiology and Clinical Immunology, Faculty of Veterinary Medicine, University of Warmia and Mazury, Olsztyn, Poland.


Kynurenic acid (KYNA) was found to be an antagonist of iontropic glutamate receptors and alpha7 nicotinic acetylcholine receptors. Furthermore, it was documented that KYNA is an agonist of G-protein coupled GPR35 receptors which are mainly present in the gastrointestinal tract. It was also found that KYNA is present in the gastrointestinal tract and that its concentration gradually increases along it. The origin of KYNA in the gastrointestinal tract is not known. Both might be synthesized from tryptophan in it or absorbed from food and other dietary products. Therefore, the aim of the study was to investigate the concentration of KYNA in animal feed. The results indicate that the highest concentration of KYNA was found in animal feeds intended for livestock. The lower amount of KYNA was detected in animal feeds for fish. Interestingly, the lowest amount of KYNA was found in dog and cat feeds. Furthermore, an analysis of KYNA content in animal food ingredients was conducted. The concentration of KYNA found in one of the ingredients – rapeseed meal – was several times higher in comparison to animal feeds studied. The content of KYNA in the remaining feed ingredients tested was significantly lower. This is the first report on the concentration of KYNA in animal feeds. There is a need for further detailed analysis leading to establishing a set of guidelines for animal feeding.


animal feed; kynurenic acid

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