Apparent total tract macronutrient digestibility of mildly cooked human-grade vegan dog foods and their effects on the blood metabolites and fecal characteristics, microbiota, and metabolites of adult dogs

Vegan, mildly cooked, and human-grade dog foods are becoming more popular, as beliefs and views of pet owners change. To our knowledge, however, dog studies have not examined the digestibility of commercial vegan diets. Therefore, the objective of this study was to determine the apparent total tract digestibility (ATTD) of mildly cooked human-grade vegan dog foods and their effects on blood metabolites and fecal microbiota, characteristics, and metabolites of adult dogs consuming them. Three commercial dog foods were tested. Two were mildly cooked human-grade vegan dog diets, while the third was a chicken-based extruded dog diet. Twelve healthy adult female beagles (7.81 +/- 0.65 kg; 7.73 +/- 1.65 yr) were used in a replicated 3 x 3 Latin Square design. The study consisted of three experimental periods, with each composed of a 7 d diet adaptation phase, 15 d of consuming 100% of the diet, a 5 d phase for fecal collection for ATTD measurement, and 1 d for blood collection for serum chemistry and hematology. During the fecal collection period, a fresh sample was collected for fecal scoring and dry matter, pH, metabolite, and microbiota measurements. All data were analyzed using the Mixed Models procedure of SAS (version 9.4). All three diets were shown to be highly digestible, with all macronutrients having digestibility values above 80%. The vegan diets had higher (P < 0.001) ATTD of fat, but lower (P < 0.05) ATTD of organic matter than the extruded diet. Dogs consuming the vegan diets had lower circulating cholesterol (P < 0.001), triglyceride (P < 0.001), and platelet (P < 0.009) concentrations and lower (P < 0.010) blood neutrophil percentages than dogs consuming the extruded diet. Dogs consuming vegan diets had lower (P < 0.001) fecal dry matter percentages, lower (P < 0.001) fecal phenol and indole concentrations, and higher (P = 0.05) fecal short-chain fatty acid concentrations than those consuming the extruded diet. Fecal bacterial alpha and beta diversities were not different (P > 0.05) among diets, but dogs consuming vegan diets had altered (P < 0.05) relative abundances of nearly 20 bacterial genera when compared with those consuming the extruded diet. In conclusion, the mildly cooked human-grade vegan dog foods tested in this study performed well, resulting in desirable fecal characteristics, ATTD, and serum chemistries. The vegan diets tested also led to positive changes to serum lipids and fecal metabolites, and interesting changes to the fecal microbial community. Lay Summary Vegan, mildly cooked, and human-grade dog foods are increasing in popularity, but few studies have been performed to examine their performance. Our objective was to determine the apparent total tract digestibility (ATTD) of mildly cooked human-grade vegan dog foods and their effects on blood metabolites and fecal microbiota, characteristics, and metabolites of dogs. Two mildly cooked human-grade vegan dog diets and a chicken-based extruded dog diet were tested using 12 healthy adult dogs in a replicated 3 x 3 Latin Square design. All diets were highly digestible, with all macronutrients having digestibility values >80%. Vegan diets had higher ATTD of fat, but lower ATTD of organic matter than the extruded diet. Dogs consuming vegan diets had lower circulating cholesterol, triglycerides, platelets, and neutrophils than dogs consuming the extruded diet. Dogs consuming vegan diets had lower fecal dry matter percentages and phenol and indole concentrations, and higher fecal short-chain fatty acid concentrations than those consuming the extruded diet. Finally, similar to 20 bacterial genera were altered between dogs consuming vegan and extruded diets. In conclusion, the mildly cooked human-grade vegan dog foods tested performed well, resulting in desirable fecal characteristics, high ATTD, adequate serum chemistries, positive changes to serum lipids and fecal metabolites, and interesting changes to fecal microbiota.

Automated summary

Vegan, mildly cooked, and human-grade dog foods are increasing in popularity, but there is a lack of research on their digestibility and effects on dogs. This study aimed to determine the digestibility of human-grade vegan dog foods and their impact on blood metabolites and fecal microbiota. The results showed that the vegan diets were highly digestible and had positive effects on blood lipids and fecal metabolites.