Effects of diet on the intestinal microbiota, bacteria-derived metabolites and digestiveenzymes in healthy dogs

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http://urn.fi/URN:ISBN: 978-951-51-0538-7
Title: Effects of diet on the intestinal microbiota, bacteria-derived metabolites and digestiveenzymes in healthy dogs
Author: Hang, Ingrid
Contributor: University of Helsinki, Faculty of Veterinary Medicine, Equine and Small Animal Medicine
Publisher: Helsingin yliopisto
Date: 2015-01-09
URI: http://urn.fi/URN:ISBN: 978-951-51-0538-7
http://hdl.handle.net/10138/152689
Thesis level: Doctoral dissertation (article-based)
Abstract: Considerable evidence suggests that dietary macronutrients impact upon activities and conditions in the gastrointestinal tract (GIT) including: functions and processes, digestive enzymes secretion, microbial ecology and bacteria-derived metabolism. Knowledge about the modulation of canine intestinal microbiota, bacteria-derived metabolic products,intestinal inflammatory status and adaptive exocrine pancreatic secretion in response to macronutrients is limited. However, such information is necessary to investigate further the complex interplay between host and intestinal microbiota in response to changes of diet. The reasearch for this PhD thesis focused upon the changes of the intestinal microbiota,bacteria-ferivedmetabolicproducts,anintestinalinflammatorymarker and pancreatic enzyme profiles of five healthy Beagle dogs in response to being fed three different diets: high-carbohydrate starch (HCS), high-protein greaves-meal (HPGM), or a balanced dry commercial (DC) diet. Every diet was crossed-over and fed to each dog for three 21-day periods. The microbial deoxyribonucleic acid (DNA) was profiled according to its percentageoftheguanine-cytosinecontent(%G+C)inordertodetectthefluctuations in intestinal microbiota. Thereafter, 16S ribosomal ribonucleic acid (16S rRNA) gene amplicons were obtained from the most abundant %G+C peaks and analysed by sequence analysis. The DC diet sample was associated with high abundances of representatives of the orders Clostridiales, Lactobacillales, Coriobacteriales and Bacteroidales. Sequence diversity was highest for the DC diet samples and included representatives of the orders Lactobacillales and Bacteroidales, which were not detected in samples obtained for the HPGM and HCS diets. The HPGM and HCS diets also had reduced numbers of representatives of the family Lachnospiraceae; specifically Clostridium cluster XIVa. The HCS diet favoured the proliferation of representatives of the order Erysipelotrichales, specifically the Clostridium cluster XVIII, whereas the HPGM diet favoured representatives of the order Fusobacteriales. Bacterial metabolism and intestinal inflammatory status were assessed by determining dry matter, pH, ammonia, short-chained fatty acids (SCFAs), and faecal canine calprotectin concentrations. Faecal ammonia concentrations decreased with the HCS diet. All dogs fed the HPGM diet developed diarrhoea, which led to differences in faecal consistency scores and increased faecal pH. Moreover, decreases in propionic and acetic acids coupled with increases in branched-chain fatty acids and valeric acid caused changes in faecal total SCFAs. Faecal canine calprotectin concentration was also higher for the HPGM diet than with the other diets and correlated positively with valeric acid concentrations.8 Dietary effects on digestive enzyme composition in the serum, in jejunal fluid, and in the faeces were studied by determining the following factors: amylase activity, the concentrations of canine trypsin-like immunoreactivity (cTLI), canine pancreatic lipase immunoreactivity (cPLI), and canine pancreatic elastase (cE1) concentrations with the two radioimmunoassays (RIAs) for determining cTLI and cPLI concentrationswere specifically validated for jejunalfluid and faecal specimen analysis. Both RIAs were linear, accurate, precise, and reproducible. Dog specific serum enzyme concentrations did not differ between diets. Feeding the HCS diet was associated with decreased amylase activities and cPLI concentrations in the lower jejunum, when compared to the corresponding cPLI activities of the HPGM and the DC diet. The HPGM diet decreased the concentrations of cPLI and cE1 in faecal samples, but not in the jejunal fluid. In conclusion, all bacterial clusters discovered in this research represent the normal GIT microbiota of canines. The HPGM diet favoured Fusobacterium and this Gram-negative bacterial genus may be associated with the observed elevated inflammation status. The latter was deduced from the observed diarrhoea and elevated levels of canine faecal calprotectin in all dogs fed the HPGM diet. It seems likely that these research results could be associated with the quality and increased or decreased amounts of dietary protein or carbohydrate being available for fermentation by the intestinal microbiota. The limited capacity of pancreatic enzymes to adapt adequately by a change inprofile inresponse to changes indietary components seems to be an essential factor, which influences the nutrient levels available for the intestinal microbiota.Knowledge about the modulation of canine intestinal microbiota, bacteria-derived metabolic products, intestinal inflammatory status and adaptive exocrine pancreatic secretion in response to macronutrients is limited. However, such information is necessary to investigate further the complex interplay between host and intestinal microbiota in response to changes of diet. DVM Ingrid Hang s reasearch for PhD thesis focuses upon the influence of dite on intestinal microbiota, bacteria-derived metabolic products and pancreatic enzymes in dogs. Hang s research suggests that a high-protein greaves-meal diet can be associated with elevated inflammation status in dogs. Considerable evidence suggests that dietary macronutrients impact upon activities and conditions in the gastrointestinal tract including: functions and processes, digestive enzymes secretion, microbial ecology and bacteria-derived metabolism. Hang s research investigates bacteria-derived metabolic products, an intestinal inflammatory marker and pancreatic enzyme profiles of five healthy Beagle dogs in response to being fed three different diets: high-carbohydrate starch, high-protein greaves-meal or a balanced dry commercial diet. Every diet was crossed-over and fed to each dog for three 21-day periods. Hang assessed bacterial metabolism and intestinal inflammatory status by determining faecal consistency scores, dry matter, pH, ammonia, short-chained fatty acids (SCFAs), and faecal canine calprotectin concentrations. Faecal ammonia concentrations decreased with the high-carbohydrate starch diet. All dogs fed the high-protein greaves-meal diet developed diarrhoea, which led to differences in faecal consistency scores and increased faecal pH. Moreover, decreases in propionic and acetic acids coupled with increases in branched-chain fatty acids and valeric acid caused changes in faecal total SCFAs. Faecal canine calprotectin concentration was also higher for the high-protein greaves-meal diet than with the other diets and correlated positively with valeric acid concentrations. Hang studied dietary effects on digestive enzyme composition in the serum, in jejunal fluid, and in the faeces by determining the following factors: amylase activity, the concentrations of canine trypsin-like immunoreactivity (cTLI), canine pancreatic lipase immunoreactivity (cPLI), and canine pancreatic elastase (cE1) concentrations with the two radioimmunoassays (RIAs) for determining cTLI and cPLI concentrations, which were specifically validated for jejunal fluid and faecal specimen analysis. Both RIAs were linear, accurate, precise, and reproducible. Dog specific serum enzyme concentrations did not differ between diets. Feeding the high-carbohydrate starch diet was associated with decreased amylase activities and cPLI concentrations in the lower jejunum, when compared to the corresponding cPLI acticities of the high-protein greaves-meal and the dry commercial diet. The high-protein greaves-meal diet decreased the concentrations of cPLI and cE1 in faecal samples, but not in the jejunal fluid. In Hang s research the microbial deoxyribonucleic acid (DNA) was profiled according to its percentage of the guanine-cytosine content (%G+C) in order to detect the fluctuations in intestinal microbiota. Thereafter, 16S ribosomal ribonucleic acid (16S rRNA) gene amplicons were obtained from the most abundant %G+C peaks and analysed by sequence analysis. According to Hang all bacterial clusters discovered in this research represent the normal gastrointestinal tract microbiota of canines. The high-protein greaves-meal diet favoured Fusobacterium and this Gram-negative bacterial genus may be associated with the observed elevated inflammation status. The latter was deduced from the observed diarrhoea and elevated levels of canine faecal calprotectin in all dogs fed the high-protein greaves-meal diet. It seems likely that these research results could be associated with the quality and increased or decreased amounts of dietary protein or carbohydrate being available for fermentation by the intestinal microbiota. The limited capacity of pancreatic enzymes to adapt adequately by a change in profile in response to changes in dietary components seems to be an essential factor, which influences the nutrient levels available for the intestinal microbiota.
Subject: small animal gastroenterology
internal medicine
Rights: This publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited.


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