Animals, Diets, and Treatments

All animal care and experimental procedures were approved by the University of Illinois Institutional Animal Care and Use Committee (Protocol No. 17276) prior to experimentation. All methods were performed in accordance with the United States Public Health Service Policy on Humane Care and Use of Laboratory Animals. Twelve adult female beagles (mean age: 5.16 ± 0.87 years; mean BW: 13.37 ± 0.68 kg) were used and housed individually in pens (1.0 m wide × 1.8 m long) in a humidity- and temperature-controlled room on a 14 h light: 10 h dark cycle. Dogs had access to fresh water ad libitum at all times. All diets were offered to dogs once a day in the morning to maintain body weight throughout the study. Dogs were weighed and body condition scores were assessed using a 9-point scale (13) weekly before feeding.

A replicated 4 × 4 Latin square design was conducted. Each 28-d experimental period consisted of an adaptation phase (d 1–14) and a diet transition phase (d 15–28). Three diets that met all Association of American Feed Control Officials (AAFCO) (14) nutrient recommendations for adult dogs at maintenance were fed, which included (1) a baseline diet (a dry kibble experimental diet; Tables 1, ​,2);2); (2) a commercial canned diet (CD; Ol' Roy Cuts in Gravy with Savory Beef; Walmart, Bentonville, AR; Table 2); and (3) a high-fiber diet (HFD) composed of the experimental diet plus 22.5 g/d of soluble corn fiber (Nutriose® Soluble Digestion-Resistant Prebiotic Corn Fiber; Roquette America Inc., Geneva, IL) that was top-dressed on the diet just prior to feeding. Treatments were given to dogs via gelatin capsules (d 1–28) prior to the diet each day, which included a placebo (125 mg cellulose/d) or yeast cell wall fraction (Safmannan® Phileo by Lesaffre, Marcq-en-Barœul, France; 365 mg/d; equivalent to 0.2% of diet). The yeast cell wall fraction tested was from Saccharomyces cerevisiae and the analyzed chemical composition is presented in Table 3. During the adaptation phase, all dogs were fed the experimental diet and supplemented with placebo or yeast product. During the diet transition phase, dogs remained on their placebo or yeast treatments, but were fed their new diet (CD or HFD). Therefore, dogs were allotted to one of four groups each experimental period: (1) Yeast CD; (2) Yeast HFD; (3) Placebo CD; and (4) Placebo HFD.

Ingredient composition of the experimental diet fed to yeast- or cellulose-supplemented dogs.

Analyzed chemical composition of the experimental diet and canned diet (CD) fed to yeast- or cellulose-supplemented dogs.

Analyzed chemical composition of the yeast cell wall fraction tested.