Effects of dietary macronutrient profile on apparent total tract macronutrient digestibility and fecal microbiota, fermentative metabolites, and bile acids of female dogs after spay surgery

Abstract

Obesity and estrogen reduction are known to affect the gut microbiota and gut microbial-derived metabolites in some species, but limited information is available in dogs. The aim of this study was to determine the effects of dietary macronutrient profile on apparent total tract macronutrient digestibility, fecal microbiota, and fecal metabolites of adult female dogs after spay surgery. Twenty-eight adult intact female beagles (age: 3.02 ± 0.71 yr, BW: 10.28 ± 0.77 kg; BCS: 4.98 ± 0.57) were used. After a 5-wk baseline phase (week 0), 24 dogs were spayed and randomly allotted to one of three experimental diets (n = 8 per group): 1) control (CO) containing moderate protein and fiber (COSP), 2) high-protein, high-fiber (HPHF), or 3) high-protein, high-fiber plus omega-3 and medium-chain fatty acids (HPHFO). Four dogs were sham-operated and fed CO (COSH). All dogs were fed to maintain BW for 12 wk after spay and then allowed to consume twice that amount for 12 wk. Fecal samples were collected at weeks 0, 12, and 24 for digestibility, microbiota, and metabolite analysis. All data were analyzed using repeated measures and linear mixed models procedure of SAS 9.4, with results reported as a change from baseline. Apparent organic matter and energy digestibilities had greater decreases in HPHF and HPHFO than COSH and COSP. Increases in fecal acetate, total short-chain fatty acids, and secondary bile acids were greater and decreases in primary bile acids were greater in HPHF and HPHFO. Principal coordinates analysis of weighted UniFrac distances revealed that HPHF and HPHFO clustered together and separated from COSH and COSP at weeks 12 and 24, with relative abundances of Faecalibacterium, Romboutsia, and Fusobacterium increasing to a greater extent and Catenibacterium, Bifidobacterium, Prevotella 9, Eubacterium, and Megamonas decreasing to a greater extent in HPHF or HPHFO. Our results suggest that high-protein, high-fiber diets alter nutrient and energy digestibilities, fecal metabolite concentrations, and fecal gut microbiota, but spay surgery had minor effects. Future research is needed to investigate how food intake, nutrient profile, and changes in hormone production influence gut microbiota and metabolites of dogs individually and how this knowledge may be used to manage spayed pets.

Keywords: canine nutrition; dietary fiber; gut health; gut microbiota; ovariectomy; pet obesity.

Figure 1.

Fecal microbial communities of sham-operated dogs fed a control diet (COSH), of spayed dogs fed a control diet (COSP), spayed dogs fed a high-protein, high-fiber diet (HPHF), and spayed dogs fed a high-protein, high-fiber diet with additional omega-3 and medium-chain fatty acids (HPHFO). (A) Shannon diversity index suggested that species richness was lower (P < 0.05) in COSH dogs than HPHFO dogs at weeks 12 and 24, and tended to be lower (P < 0.10) in COSH dogs than HPHF dogs at weeks 12 and 24. COSP-12: COSP dogs at week 12; COSP-24: COSP dogs at week 24; HPHF-12: HPHF dogs at week 12; HPHF-24: dogs at week 24; HPHFO-12: HPHFO dogs at week 12; HPHFO-24: HPHFO dogs at week 24. **Mean values differ (P < 0.05). *Mean values tend to differ (P < 0.10). (B) Principal coordinates analysis (PCoA) plots of weighted UniFrac distances of fecal microbial communities of all dogs revealed that dogs fed HPHF or HPHFO clustered together and separately from dogs fed the control diet (COSH or COSP) at weeks 12 and 24 (P < 0.05). (C) PCoA plots of unweighted UniFrac distances of fecal microbial communities of all dogs were not different among treatment groups (P > 0.05). (D) PCoA plots of weighted UniFrac distances of fecal microbial communities of spayed dogs revealed that dogs fed HPHF or HPHFO clustered together and separately from dogs fed the control diet (COSP) at weeks 12 and 24 (P < 0.05). (E) PCoA plots of unweighted UniFrac distances of fecal microbial communities of spayed dogs (P > 0.05).

Figure 2.

Change from baseline relative abundance (%) of fecal (A) Actinobacteria, (B) Bacteroidetes, (C) Firmicutes, (D) Fusobacteria, and (E) Proteobacteria phyla and (F) Firmicutes: Bacteroidetes ratio of spayed dogs fed the control diet (COSP), spayed dogs fed a high-protein, high-fiber diet (HPHF), and spayed dogs fed a high-protein, high-fiber diet with additional omega-3 and medium-chain fatty acids (HPHFO). COSP-12: COSP dogs at week 12; COSP-24: COSP dogs at week 24; HPHF-12: HPHF dogs at week 12; HPHF-24: dogs at week 24; HPHFO-12: HPHFO dogs at week 12; HPHFO-24: HPHFO dogs at week 24. Data are represented as the change from baseline (week 0) least squares means ± SEM.

Figure 3.

Change from baseline relative abundance (%) of fecal (A) Bifidobacterium, (B) Prevotella 9, (C) Catenbacterium, (D) Eubacterium, (E) Faecalibacterium, (F) Lactobacillus, (G) Megamonas, (H) Romboutsia, (I) Ruminococcus Torques group, and (J) Fusobacterium genera of spayed dogs fed a CO diet (COSP); spayed dogs fed a high-protein, high-fiber diet (HPHF), and spayed dogs fed a high-protein, high-fiber diet with additional omega-3 and medium-chain fatty acids (HPHFO). COSP-12: COSP dogs at week 12; COSP-24: COSP dogs at week 24; HPHF-12: HPHF dogs at week 12; HPHF-24: dogs at week 24; HPHFO-12: HPHFO dogs at week 12; HPHFO-24: HPHFO dogs at week 24. Data are represented as the change from baseline (week 0) least squares means ± SEM. ^a–cDifferent letters differ (P < 0.05).