Effects of yeast-enriched functionalized canola meal supplementation on apparent total tract macronutrient digestibility and fecal characteristics, fecal microbiota, and immune function of healthy adult dogs

Brewer's dried yeast has a high nutritional value and has long been utilized by the animal feed industry as a source of protein, B-complex vitamins, and minerals. Brewer's dried yeast is also rich in bioactive compounds and may thereby be used as a functional ingredient, providing benefits beyond that of its nutrient content. Canola meal is a high-fiber ingredient that also has unique properties, especially when it is wetted and dried using a proprietary drying system that creates a "functionalized" canola meal. The objective of this experiment was to evaluate the effects of a yeast-enriched functionalized canola meal (FCM) on apparent total tract digestibility (ATTD) and the fecal quality, metabolite concentrations, and microbiota populations, and immune function of healthy adult dogs. Twelve adult female beagles (body weight [BW] = 7.6 +/- 0.7 kg; age = 5.8 +/- 1.3) were used in a replicated 4 x 4 Latin square design with 28-d periods. Each experimental period consisted of a 22-d adaptation phase, 5 d of total and fresh fecal collection, and blood collection on the last day. To start, all dogs were fed a basal diet to maintain BW for 14 d. Following fecal and blood collections at baseline (-1 d) to confirm health status, experimental periods began testing the following dietary treatments using a Latin square design experiment: 1) FCM only (no yeast inclusion), 2) FCM + low yeast dose, 3) FCM + medium yeast dose, and 4) FCM + high yeast dose. All treatments were top-dressed onto the basal diet at a rate estimated to be 1% of daily intake (as-is basis). Statistical analysis was performed using the PROC MIXED procedure of SAS with the main effect of treatment and the random effect of dog. Significance was declared at P <= 0.05, and trends reported if 0.05 < P <= 0.10. Supplementation with yeast-enriched FCM had no significant effect on the ATTD of macronutrients or energy or the fecal characteristics, metabolite concentrations, and microbiota populations of dogs. Additionally, no significant differences were observed in circulating immune cell counts or response to Toll-like receptor agonists among treatments. Our results suggest that the yeast-enriched FCM could be included in canine diets without negatively affecting stool quality, fecal metabolite concentrations, or ATTD. Further research is necessary to determine the effective dose of yeast-enriched FCM, potential mechanisms of action, and other potential implications it has on canine health.