Evaluation of faba beans as an ingredient in dog diets: apparent total tract digestibility of extruded diets with graded levels of dehulled faba beans (Vicia faba L.) by dogs

The growing pet food market is continuously in search for novel ingredients. Legumes such as faba beans (FB) are increasing in popularity and are known to benefit human health, but little is known about their use in pet foods. The objective of this study was to determine the effect of dehulled FB utilization by dogs. Experimental diets were extruded with 0%, 10%, 20%, and 30% FB inclusion (FB0, FB10, FB20, and FB30, respectively). Beagle dogs (n = 12) were fed the diets for 9-d adaptation with 5-d total fecal collection in a replicated 4 × 4 Latin square design. Apparent total tract digestibility (ATTD) was determined by external marker Cr(2)O(3). At the culmination of each period, blood samples were collected from brachial venipuncture for complete blood count and blood chemistry. Palatability was determined with a 2-bowl test (n = 20). Means of blood parameters were separated by multivariate analysis of variance (MANOVA) with the aid of statistical software (SAS v9.4). Contrasts and least square means of fecal parameters and ATTD were computed. Significance level was considered to be α = 0.05. Dogs ate all food on offer and maintained body weight. There was no difference (P > 0.05) among treatments (FB10, FB20, and FB30) and the control (FB0) relative to food intake, fecal output (“as is” basis), and fecal score, but feces were softer when dogs were fed the treatments (P = 0.031) and there was a linear increase (P = 0.011) in defecation frequency (stools/day) when FB increased in the diets. Dry matter, organic matter, and crude protein digestibilities were slightly higher when dogs were fed the control diet (P < 0.05) compared with the FB diets. All blood and serum chemistry parameters were similar among treatments and within the reference ranges. Dogs preferred the control diet relative to the 10% and 30% FB diets, but the 20% FB preference was similar to the control. Dogs remained healthy, maintained body weight and no adverse health events were observed during the study. Dehulled FB are a suitable ingredient for dog foods, but concentrations should not exceed 20% to avoid reduction in palatability and stool quality.