Key bacterial families (Clostridiaceae, Erysipelotrichaceae and Bacteroidaceae) are related to the digestion of protein and energy in dogs

Abstract

Background: Much of the recent research in companion animal nutrition has focussed on understanding the role of diet on faecal microbiota composition. To date, diet-induced changes in faecal microbiota observed in humans and rodents have been extrapolated to pets in spite of their very different dietary and metabolic requirements. This lack of direct evidence means that the mechanisms by which microbiota influences health in dogs are poorly understood. We hypothesised that changes in faecal microbiota correlate with physiological parameters including apparent macronutrient digestibility.

Methods: Fifteen adult dogs were assigned to two diet groups, exclusively fed either a premium kibbled diet (kibble; K; n = 8) or a raw red meat diet (meat; M; n = 7) for nine weeks. Apparent digestibility of macronutrients (protein, fat, gross energy and dry matter), faecal weight, faecal health scores, faecal VFA concentrations and faecal microbial composition were determined. Datasets were integrated using mixOmics in R.

Results: Faecal weight and VFA levels were lower and the apparent digestibility of protein and energy were higher in dogs on the meat diet. Diet significantly affected 27 microbial families and 53 genera in the faeces. In particular, the abundances of Bacteriodes, Prevotella, Peptostreptococcus and Faecalibacterium were lower in dogs fed the meat diet, whereas Fusobacterium, Lactobacillus and Clostridium were all more abundant.

Discussion: Our results show clear associations of specific microbial taxa with diet composition. For example, Clostridiaceae, Erysipelotrichaceae and Bacteroidaceae were highly correlated to parameters such as protein and fat digestibility in the dog. By understanding the relationship between faecal microbiota and physiological parameters we will gain better insights into the effects of diet on the nutrition of our pets.

Keywords: Dog; Faecal microbiota; Nutrient digestibility.

Figure 1. Heat maps indicating study design.

Heat maps faecal bacteria levels in the dog (reported at the family level) and physiological markers of intestinal function in dogs fed both the kibbled and meat diet. To enhance the display of a large range of values in both cases, the log₂ transformed macronutrient data and square root of the bacterial family data are displayed.

Figure 2. Correlation heat map describing the associations between faecal bacteria families and physiological markers of intestinal function in dogs fed both the kibbled and meat diet.

Correlation heat map describing the associations between faecal bacteria levels in the dog (reported at the family level) and physiological markers of intestinal function in dogs fed both the kibbled and meat diet. Correlations greater than 0.50 were considered highly positively correlated, whereas correlations below −0.50 were considered to be highly negatively correlated. DM, Dry matter.

Figure 3. A relevance network plot (0.6 correlation cutoff) of the first two canonical dimensions of canonical correlation analysis using shrinkage.

A relevance network plot (0.6 correlation cutoff) of the first two canonical dimensions of canonical correlation analysis of faecal 16S genomic DNA amplicon data with physical measurement and metabolomics data using shrinkage reveals Clostridiaceae as a central node.