Cover design by LumaDox Merelbeke, Belgium, www.lumadox.be Painting for cover and drawing for chapter title pages by Jia Xu Printing by DCL University Press Zelzate, Belgium, www.dclsigns.be Can fermentation-derived propionic acid spare glucogenic amino acids in domestic cats? Kristel Rochus Promotors: Prof. dr. M. Hesta & Prof. dr. ir. G.P.J. Janssens Department of Nutrition, Genetics and Ethology Faculty of Veterinary Medicine, Ghent University Heidestraat 19, B-9820 Merelbeke, Belgium Dissertation submitted in fulfilment of the requirements for the degree of doctor in Veterinary Science (PhD), Faculty of Veterinary Medicine, Ghent University, 2013 Table of contents TABLE OF CONTENTS List of abbreviations ...................................................................................................... 9 Chapter 1: General Introduction ............................................................................... 15 1.1 Abstract .................................................................................................................. 17 1.2 Fermentation in the carnivorous domestic cat? ..................................................... 18 1.3 Overview of in vivo fermentation studies in the domestic cat ............................... 34 1.4 Conclusions ............................................................................................................ 47 1.5 References .............................................................................................................. 48 Chapter 2: Scientific Aims ........................................................................................... 57 Chapter 3: In vitro evaluation of fermentation profiles of different plant fibre sources .......................................................................................................................... 63 3.1 Abstract .................................................................................................................. 65 3.2 Introduction ............................................................................................................ 66 3.3 Materials and Methods ........................................................................................... 67 3.4 Results .................................................................................................................... 73 3.5 Discussion .............................................................................................................. 79 3.6 Conclusions ............................................................................................................ 85 3.7 Acknowledgements ................................................................................................ 85 3.8 References .............................................................................................................. 86 Chapter 4: Dietary highly viscous guar gum as a model to study the amino acid sparing potential of fermentation-derived propionic acid ......................................... 91 4.1 Abstract .................................................................................................................. 93 4.2 Introduction ............................................................................................................ 94 4.3 Materials and methods ........................................................................................... 96 4.4 Results .................................................................................................................. 100 4.5 Discussion ............................................................................................................ 107 4.6 Conclusions .......................................................................................................... 111 5 Table of contents 4.7 Acknowledgements .............................................................................................. 111 4.8 References ............................................................................................................ 112 Chapter 5: Dietary propionylated starch as a model to study the amino acid sparing potential of fermentation-derived propionic acid ..................................................... 117 5.1 Abstract ................................................................................................................ 119 5.2 Introduction .......................................................................................................... 120 5.3 Materials and Methods ......................................................................................... 121 5.4 Results .................................................................................................................. 126 5.5 Discussion ............................................................................................................ 131 5.6 Conclusions .......................................................................................................... 137 5.7 Acknowledgements .............................................................................................. 138 5.8 References ............................................................................................................ 139 Chapter 6: General Discussion ................................................................................. 143 6.1 Introduction .......................................................................................................... 145 6.2 Non-invasive estimation of hindgut fermentation in domestic cats ..................... 146 6.3 The link between fermentation-derived propionic acid, the gluconeogenesis and amino acid sparing ............................................................................................... 157 6.4 Practical and clinical relevance of amino acid sparing in domestic cats ............. 160 6.5 Future perspectives .............................................................................................. 162 6.6 Conclusions .......................................................................................................... 165 6.7 References ............................................................................................................ 166 Summary .................................................................................................................... 171 Samenvatting .............................................................................................................. 177 Curriculum Vitae ....................................................................................................... 183 Bibliography ............................................................................................................... 187 Acknowledgements ..................................................................................................... 191 Addendum .................................................................................................................. 199 6 List of abbreviations List of abbreviations AC amylopectin cluster ADF acid detergent fibre AM alfalfa meal ANOVA analysis of variance AOAC Association of Official Analytical Chemists AUC area under the curve AXOS arabinoxylan oligosaccharides Bacter Bacteroides BCFA branched-chain fatty acid BCS body condition score Bifido Bifidobacteria BMI body mass index BP beet pulp CA crude ash Cell cellulose CF crude fibre CFU colony forming units CH3 methyl CKD chronic kidney disease CoA coenzyme A CP crude protein CRI constant rate infusion 9 List of abbreviations DGGE denaturing gradient gel electrophoresis DM dry matter DP degree of polymerization DS degree of substitution EBC exhaled breath condensate EC ethical committee EE diethyl ether extract FOS fructooligosaccharides GC gas chromatography GG guar gum GIT gastrointestinal tract GOS galactooligosaccharides H2 hydrogen gas HAMSA acetylated high amylose maize starch HAMSP propionylated high amylose maize starch HE hepatic encephalopathy HF high fibre, moderate protein HMG 3-hydroxy 3-methylglutaryl ISO international organization of standardization isobut isobutyric isoval isovaleric IV intravenous Lacto Lactobacilli 10 List of abbreviations LC liquid chromatography LF low fibre, high protein LSD least significant differences LVGG lower viscosity guar gum ME metabolizable energy MER maintenance energy requirement MP missing parameter mPa.s milliPascal seconds MPE mean prediction error MOS mannanoligosaccharides MS mass spectrometry NA not applicable ND not detectable NDF neutral detergent fibre NFE nitrogen-free extract NH3 ammonia + NH4 ammonium NP non-parametrically NRC National Research Council NS not significant NSP non-starch polysaccharides OF oligofructose OH hydroxyl 11 List of abbreviations OM organic matter OMCV organic matter corrected volume OMD organic matter disappearance param parameter PCR polymerase chain reaction PI protein intake PIA protein intake above minimal requirements PIB protein intake below minimal requirements PH peanut hulls ppm part per million Rmax maximum rate of gas production rpm rounds per minute RS resistant starch RT real time SA Satterthwaite approximation SAS statistical analysis system sc short-chain SCFA short-chain fatty acid SD standard deviation SEM standard error of the mean SF sugarcane fibre SUL safe upper limit TCA tricarboxylic acid 12 List of abbreviations TDF total dietary fibre TFA total food amount Tmax time of occurrence of the maximum rate of gas production Treat treatment