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

Raw diets are now commercially available for the canine, but few studies have been conducted testing their nutritional value. The objective of this experiment was to determine the effects of feeding poultryand beef-based raw diets, with or without inulin or yeast cell wall extract (YCW), on total tract apparent macronutrient digestibility, blood cell populations, serum metabolite concentrations, and fecal fermentative end-product concentrations in healthy adult dogs. Six healthy, adult female beagles (5.5 ± 0.5 yr; 8.5 ± 0.5 kg) were randomly allotted to the following diets using a Latin square design: 1) Beef control; 2) Beef + 1.4% inulin (dry matter basis; DMB); 3) Beef + 1.4% YCW (DMB); 4) Chicken control; 5) Chicken + 1.4% inulin (DMB); and 6) Chicken + 1.4% YCW (DMB). Each period lasted 21 d (d 0-14 adaptation; d 1520 total and fresh fecal and urine collection; d 21 fasted blood sample). Dogs were fed to maintain BW throughout the study. Food intake and refusals were measured daily. All dogs maintained desirable stool quality characteristics and produced low stool volume. All diets were highly digestible (total tract crude protein digestibility: 88.1-92.3%; fat digestibility: 96.797.8%). There were minor changes in fermentative end-product concentrations, but fecal shortchain fatty acid (SCFA) 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. All diets maintained nitrogen balance. To evaluate the standardized amino acid digestibility of the six raw meat-based diets, a cecectomized rooster assay was conducted. 38 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 were measured in each sample. The results of the cecectomized rooster assay indicated 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 previous feline studies, demonstrating a high nutrient digestibility of raw diets in dogs. 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. Introduction The use of unconventional diets, including raw meat diets, for pets continues to increase in popularity. Raw meat-based diets, as with other diets, have both potential benefits and risks. As seen previously in cats, 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 (Michel, 2006; Kerr et al., 2010b; Vester et al., 2010a; 2010b). Conversely, raw meat-based diets have been shown to increase pathogen exposure, contain nutritional imbalances in some cases, and may be inconvenient for the pet owner to store or feed (Freeman and Michel, 2001; LeJeune and Hancock, 2001; Weese et al., 2005; Michel, 2006; 2008). To reduce health risks to both pet owners and their companion animals, the Center for Veterinary Medicine (CVM) has recommended specific guidelines to be followed by the manufacturer and consumer (CVM,