title: Dietary cysteic acid serves as a precursor of taurine for cats.
abstract: The ability of cats to use dietary cysteic acid as a precursor for taurine was examined. For 39 wk, six groups of four specific-pathogen-free cats each were fed purified diets that provided either 1.25 g taurine or 0, 1.0, 2.0, 10 or 20 g cysteic acid/kg diet. Concentrations of taurine in plasma and whole blood were measured weekly for 13 wk and monthly until 39 wk. Muscle concentrations of taurine at 12 wk were measured on a biopsy sample of the semitendinosus muscle. Fecal and urinary excretions of taurine and cysteic acid at 17 wk were measured. Concentrations of taurine in plasma and whole blood were linearly and positively correlated with cysteic acid in the diet (r2 = 0.88). Urinary taurine, a major route of excess taurine excretion, was positively correlated with the cysteic acid concentration of the diet (r2 = 0.94). Muscle and whole-blood taurine concentrations were also positively correlated (r2 = 0.96) with dietary cysteic acid concentration. Gross and histopathological examinations were performed on cats fed diets containing 20 g cysteic acid/kg diet. No adverse gross clinical signs were observed in cats fed any diets containing cysteic acid; minor histopathologic changes of the pancreas and thyroid were found in three of four cats fed 20 g cysteic acid/kg diet. Results suggest that cats are able to use dietary cysteic acid as a precursor for taurine biosynthesis.
authors.affiliation: Department of Physiological Sciences, School of Veterinary Medicine, University of California, Davis 95616-8741.
authors.forename: S E
authors.initials: SE
authors.lastname: Edgar
authors.forename: M A
authors.initials: MA
authors.lastname: Hickman
authors.forename: M M
authors.initials: MM
authors.lastname: Marsden
authors.forename: J G
authors.initials: JG
authors.lastname: Morris
authors.forename: Q R
authors.initials: QR
authors.lastname: Rogers
mesh_terms: D000284:Administration, Oral; D000704:Analysis of Variance; D000818:Animals; D002415:Cats / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D003544:Cysteic Acid / Q000008:administration & dosage / Q000378:metabolism*; D004032:Diet; D004305:Dose-Response Relationship, Drug; D005243:Feces / Q000737:chemistry; D005260:Female; D006863:Hydrogen-Ion Concentration; D008137:Longitudinal Studies; D008297:Male; D009132:Muscles / Q000378:metabolism; D013047:Specific Pathogen-Free Organisms; D013654:Taurine / Q000008:administration & dosage / Q000032:analysis / Q000378:metabolism*; D014556:Urine / Q000737:chemistry
chemical_list: D013654:Taurine; D003544:Cysteic Acid