Intestinal fermentation modulates postprandial acylcarnitine profile and nitrogen metabolism in a true carnivore: The domestic cat (felis catus)

Abstract

N balance and postprandial acylcarnitine profile following intestinal fermentation of oligofructose and inulin were investigated in healthy cats. Two diets were tested in a crossover design: a commercial high-protein cat food supplemented with 4% DM oligofructose and inulin (spectrum: degree of polymerisation (DP) 2-10: 60 (se 5)% DM; DP>10: 28 (se 5)% DM) as high-fermentable fibre (HFF) diet, and the same commercial diet supplemented with 4% DM cellulose as low-fermentable fibre diet. Eight adult cats were randomly allotted to each of the two diets at intervals of 4 weeks. At the end of each testing period, faeces and urine were collected over a 5-d period, and blood samples were obtained before and at the selected time points postprandially. No differences were found for N intake, N digestibility and faecal N excretion, whereas urinary N excretion was lower when the HFF diet was fed (P=0044). N balance was positive in all the cats, and tended to be increased when the HFF diet was fed (P=0079). Propionylcarnitine concentrations (P=0015) and their area under the curve (AUC) (P=0013) were increased when the HFF diet was fed, revealing a more pronounced production and absorption of propionate. Yet, methylmalonylcarnitine concentrations and concurrent AUC were not elevated when the HFF diet was fed, indicating reduced amino acid catabolism. 3-Hydroxy-3-methylglutarylcarnitine concentrations (P=0026) and their AUC (P=0028) were also reduced when the HFF diet was fed, implying diminished use of branched-chain amino acids as well. In healthy cats, oligofructose and inulin added to a high-protein diet were suggested to reduce postprandial amino acid-induced gluconeogenesis by substitution with propionate. © The Authors 2010.