Impact of diets with a high content of greaves-meal protein or carbohydrates on faecal characteristics, volatile fatty acids and faecal calprotectin concentrations in healthy dogs.

BACKGROUND: Research suggests that dietary composition influences gastrointestinal function and bacteria-derived metabolic products in the dog colon. We previously reported that dietary composition impacts upon the faecal microbiota of healthy dogs. This study aims at evaluating the dietary influences on bacteria-derived metabolic products associated with the changes in faecal microbiota that we had previously reported. We fed high-carbohydrate starch based (HCS), [crude protein: 194 g/kg, starch: 438 g/kg], high-protein greaves-meal (HPGM), [crude protein: 609 g/kg, starch: 54 g/kg] and dry commercial (DC), [crude protein: 264 g/kg, starch: 277 g/kg] diets, and studied their effects on the metabolism of the colonic microbiota and faecal calprotectin concentrations in five Beagle dogs, allocated according to the Graeco-Latin square design. Each dietary period lasted for three weeks and was crossed-over with washout periods. Food intake, body weight, and faecal consistency scores, dry matter, pH, ammonia, volatile fatty acids (VFAs), and faecal canine calprotectin concentrations were determined. RESULTS: Faecal ammonia concentrations decreased with the HCS diet. All dogs fed the HPGM diet developed diarrhoea, which led to differences in faecal consistency scores between the diets. Faecal pH was higher with the HPGM diet. Moreover, decreases in propionic and acetic acids coupled with increases in branched-chain fatty acids and valeric acid caused changes in faecal total VFAs in dogs on the HPGM diet. Faecal canine calprotectin concentration was higher with the HPGM diet and correlated positively with valeric acid concentration. CONCLUSIONS: The HPGM diet led to diarrhoea in all dogs, and there were differences in faecal VFA profiles and faecal canine calprotectin concentrations.

Analytical validation of radioimmunoassays for the quantification of select pancreatic enzymes in jejunal fluid and fecal extracts from dogs.

Pancreatic enzymes, such as trypsin and lipase, are essential for the digestion of dietary components in the small intestine. Measurement of both enzymes in jejunal fluid and fecal specimens from dogs has not been reported and will be a prelude for further investigations. Therefore, the aim of the study was to validate radioimmunoassays (RIAs) for the measurement of canine trypsin-like immunoreactivity (cTLI) and pancreatic lipase immunoreactivity (cPLI) in jejunal fluid and fecal specimens from dogs. Jejunal fluid and fecal specimens were collected from five healthy Beagles. A commercial (125)I-RIA was used for measuring cTLI concentrations and an in-house (125)I-RIA was modified for the quantification of cPLI in jejunal fluid and fecal specimens. Both RIAs were analytically validated for canine jejunal fluid and fecal specimens by determining dilutional parallelism, spiking recovery, and intra- and inter-assay variability. For both cTLI and cPLI in jejunal fluid, observed-to-expected ratios for dilutional parallelism and spiking recovery ranged from ≥77.0% to ⩽115.3% and ≥79.0% to ≤ 120.0%, respectively, and from ≥87.2% to ≤ 118.5% and ≥74.6% to ≤ 116.1%, respectively, for fecal specimens. Intra- and inter-assay coefficients of variation (%CV) for both cTLI and cPLI in jejunal fluid were ≤ 7.6% and ≤ 10.0%, respectively, and were ≤ 10.8% and ≤ 9.0%, respectively, for fecal specimens. Both RIAs were demonstrated to be linear, accurate, precise, and reproducible for use with jejunal fluid and fecal specimens from dogs. These results are important for the investigation of pancreatic enzyme concentrations in the gastrointestinal lumen in response to changes in dietary components.

Effect of high contents of dietary animal-derived protein or carbohydrates on canine faecal microbiota.

BACKGROUND: Considerable evidence suggests that food impacts both the gastro-intestinal (GI) function and the microbial ecology of the canine GI tract. The aim of this study was to evaluate the influence of high-carbohydrate (HC), high-protein (HP) and dry commercial (DC) diets on the canine colonic microbiota in Beagle dogs. Diets were allocated according to the Graeco-Latin square design. For this purpose, microbial DNA was isolated from faecal samples and separated by density gradient centrifugation, resulting in specific profiling based on the guanine-cytosine content (%G+C). In addition, 16 S rRNA gene amplicons were obtained from the most abundant %G + C peaks and analysed by sequence analysis, producing a total of 720 non-redundant sequences (240 sequences per diet). RESULTS: The DC diet sample showed high abundance of representatives of the orders Clostridiales, Lactobacillales, Coriobacteriales and Bacteroidales. Sequence diversity was highest for DC diet samples and included representatives of the orders Lactobacillales and Bacteroidales, which were not detected in samples from the HP and HC diets. These latter two diets also had reduced levels of representatives of the family Lachnospiraceae, specifically Clostridial cluster XIVa. The HC diet favoured representatives of the order Erysipelotrichales, more specifically the Clostridial cluster XVIII, while the HP diet favoured representatives of the order Fusobacteriales. CONCLUSIONS: This study detected Coriobacteriales in dog faeces, possibly due to the non-selective nature of the %G + C profiling method used in combination with sequencing. Moreover, our work demonstrates that the effect of diet on faecal microbiota can be explained based on the metabolic properties of the detected microbial taxa.