Nutritional Evaluation of Diverse Protein Sources for Companion Dogs

This study was conducted to investigate differences in the apparent total tract digestibility (ATTD) of nutrients and amino acids among different protein sources in companion dogs and to comprehensively evaluate their applicability as pet food ingredients through blood analysis, fecal quality assessment, and palatability evaluation. Twenty Beagle dogs, including eight puppies, eight adult dogs, and four senior dogs, were fed diets containing one of six protein sources: chicken breast meal (CM), beef meal (BM), black soldier fly larvae (BSFL), mealworms (MW), dried Alaska pollock, or isolated soy protein. Following a 7-day adaptation period, total fecal collection was performed for 4 consecutive days to calculate the ATTD. The results showed that dogs fed CM and BM diets exhibited relatively higher digestibility of dry matter, crude protein, metabolizable energy, and most amino acids, whereas lower digestibility was observed in dogs fed BSFL and MW diets. These protein source-dependent digestibility patterns were generally consistent when the data were analyzed separately according to life stage. The results of the blood analysis, fecal quality indices, and palatability assessment based on a multi-bowl test indicated that all experimental diets evaluated in this study were generally acceptable in terms of physiological safety, digestive stability, and palatability. Overall, the findings of this study provide empirical evidence supporting the diversification of protein sources and expanded utilization of alternative ingredients in the companion dog food industry by comparatively characterizing nutrient and amino acid utilization across protein source–based diets.