Effects of inulin or yeast cell wall extract on nutrient digestibility and fecal fermentative end-product concentrations of healthy adult dogs fed raw diets

The use of raw meat diets for pets continues to increase in popularity. Owners may choose to feed either homemade or commercially available raw meat-based diets. Raw meat-based diets often are fed because they do not contain preservatives, are highly digestible, and may improve stool quality or skin/coat quality, with many of these claims being substantiated by peer-reviewed research reports. Despite their potential benefits, raw diets also pose many potential risks. Raw meat-based diets have been shown to increase pathogen exposure, contain nutritional imbalances if not carefully formulated and monitored, and may be inconvenient for the pet owner to store or feed. Despite the proposed advantages and risks of feeding raw diets, little research has been performed to test their nutritional adequacy and safety. Due to the growing trend of pet owners choosing to feed raw meat-based diets, research on the nutrient composition and palatability of such diets, and testing their effects on stool characteristics, nutrient digestibility, fecal fermentative end-product concentrations, and fecal microbial populations is needed. The objective of this research was to determine the effects of inulin or yeast cell wall extract (YCW) on macronutrient digestibility, blood cell and metabolite concentrations, and fecal fermentative end-product concentrations in healthy adult dogs fed raw diets. Six adult female beagles (5.5 ?? 0.5 yr; 8.5 ?? 0.5 kg) were randomly allotted to the following diets using a 3 x 2 factorial in a Latin square design: 1) Beef control; 2) Beef + 1.4% inulin dry matter basis (DMB; Orafti HP, BENEO Group, Tienan, Belgium); 3) Beef + 1.4% YCW (DMB; Bio-Mos, Alltech Biotechnology, Nicholasville, KY); 4) Chicken control; 5) Chicken + 1.4% inulin (DMB); 6) Chicken + 1.4% YCW (DMB). All dogs maintained desirable stool quality characteristics, produced low stool volume, and diets were highly digestible (protein digestibility >88%; fat digestibility >97%). There were minor changes in fermentative end-product concentrations, but fecal short-chain fatty acid concentrations were increased (P<0.05) with inulin and YCW inclusion in dogs fed beef-based diets. Fecal spermine concentrations were increased (P<0.05) with inulin and YCW inclusion. In general, blood cell populations and metabolites were within the normal ranges for dogs. To evaluate the standardized amino acid digestibility of the six raw meat-based diets, a cecectomized rooster assay was conducted. Twenty-four, Single Comb White Leghorn cecectomized roosters were used in this study. Each rooster was crop-intubated and given an average of 24 g of each test diet. All excreta were collected and amino acid concentrations measured in each sample. The results of the cecectomized rooster assay indicate that the standardized amino acid digestibility was high for all diets; however, differences in amino acid digestibility existed between protein sources. The beef control diet had the lowest total essential amino acid (TEAA), total non-essential amino acid (TNEAA), and total amino acid (TAA) digestibilities (90.2, 88.7, and 85.9%, respectively) and the chicken + inulin diet had the highest TEAA, TNEAA, and TAA digestibilities (95.6, 95.2, and 92.2%, respectively). Our results agree with those from feline studies demonstrating a high nutrient digestibility of raw diets. Inulin and YCW inclusion in raw meat-based diets had similar effects on large intestinal fermentation as extruded diets containing inulin and YCW. More research is needed to confirm our data and study such diets when fed long term.