title: Highly viscous guar gum shifts dietary amino acids from metabolic use to fermentation substrate in domestic cats.
abstract: The present study evaluated the potential of affecting amino acid metabolism through intestinal fermentation in domestic cats, using dietary guar gum as a model. Apparent protein digestibility, plasma fermentation metabolites, faecal fermentation end products and fermentation kinetics (exhaled breath hydrogen concentrations) were evaluated. Ten cats were randomly assigned to either guar gum- or cellulose-supplemented diets, that were fed in two periods of 5 weeks in a crossover design. No treatment effect was seen on fermentation kinetics. The apparent protein digestibility (P= 0.07) tended to be lower in guar gum-supplemented cats. As a consequence of impaired small-intestinal protein digestion and amino acid absorption, fermentation of these molecules in the large intestine was stimulated. Amino acid fermentation has been shown to produce high concentrations of acetic and butyric acids. Therefore, no treatment effect on faecal propionic acid or plasma propionylcarnitine was observed in the present study. The ratio of faecal butyric acid:total SCFA tended to be higher in guar gum-supplemented cats (P= 0.05). The majority of large-intestinal butyric acid is absorbed by colonocytes and metabolised to 3-hydroxy-butyrylcoenzyme A, which is then absorbed into the bloodstream. This metabolite was analysed in plasma as 3-hydroxy-butyrylcarnitine, which was higher (P= 0.02) in guar gum-supplemented cats. In all probability, the high viscosity of the guar gum supplement was responsible for the impaired protein digestion and amino acid absorption. Further research is warranted to investigate whether partially hydrolysed guar gum is useful to potentiate the desirable in vivo effects of this fibre supplement.
authors.affiliation: Department of Nutrition, Genetics and Ethology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium. kristel.rochus@ugent.be
authors.forename: Kristel
authors.initials: K
authors.lastname: Rochus
authors.forename: Geert P J
authors.initials: GP
authors.lastname: Janssens
authors.forename: Hannelore
authors.initials: H
authors.lastname: Van de Velde
authors.forename: Adronie
authors.initials: A
authors.lastname: Verbrugghe
authors.forename: Birgitte
authors.initials: B
authors.lastname: Wuyts
authors.forename: Lynn
authors.initials: L
authors.lastname: Vanhaecke
authors.forename: Myriam
authors.initials: M
authors.lastname: Hesta
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001835:Body Weight; D020148:Butyric Acid / Q000032:analysis / Q000378:metabolism; D002331:Carnitine / Q000031:analogs & derivatives / Q000097:blood; D002415:Cats / Q000378:metabolism*; D002482:Cellulose / Q000008:administration & dosage; D018592:Cross-Over Studies; D004032:Diet / Q000662:veterinary*; D004043:Dietary Fiber / Q000008:administration & dosage*; D004044:Dietary Proteins / Q000378:metabolism; D004063:Digestion / Q000187:drug effects; D002149:Energy Intake; D005232:Fatty Acids, Volatile / Q000032:analysis; D005243:Feces / Q000737:chemistry; D005260:Female; D005285:Fermentation / Q000187:drug effects*; D005685:Galactans / Q000008:administration & dosage* / Q000737:chemistry; D007413:Intestinal Mucosa / Q000378:metabolism; D008297:Male; D008351:Mannans / Q000008:administration & dosage* / Q000737:chemistry; D053149:Plant Gums / Q000008:administration & dosage* / Q000737:chemistry; D014783:Viscosity
chemical_list: D000596:Amino Acids; D004043:Dietary Fiber; D004044:Dietary Proteins; D005232:Fatty Acids, Volatile; D005685:Galactans; D008351:Mannans; D053149:Plant Gums; C513202:hydroxybutyrylcarnitine; D020148:Butyric Acid; D002482:Cellulose; C007894:guar gum; D002331:Carnitine