Apparent and true digestibility of macro and micro nutrients in adult maintenance dog foods

Macronutrients include carbohydrates, protein, and fats, which are required in large quantities in the diet. Micronutrients include vitamins and minerals, which are required in much smaller quantities. In canine studies, the macronutrient digestibility of feed is well understood, while micronutrient digestibility is not. Understanding micronutrient digestibility is important because bioavailability can vary depending on the type of feed being used, particularly for minerals. This means despite chemically containing the same quantity of a particular mineral, the digestibility of that mineral from two difference sources can be vastly different. It is for this reason that the authors of this recent Journal of Animal Science study chose to study the digestibility of micronutrients in dogs.
Eight adult beagles were fed an animal-protein (diet 1) or plant-protein (diet 2) based diet for 10 days. Both diets met basic Association of American Feed Control Officials (AAFCO) nutrient requirements for adult dogs. Titanium dioxide was used as a marker to estimate macro- and micro- nutrient digestibility. Fecal samples were collected and analyzed at the end of the study. Results indicated that there was little difference between the apparent digestibility of the two diets. However, the true digestibility of diet 2 was overall significantly better than diet 1.
The results of this study suggest that the protein source of feed may impact the digestibility of micronutrients for adult Beagles. Larger studies looking at more types of commercial dog food with different base ingredients would be a valid topic for future studies. Although it appears that the plant-protein based diet had better total digestibility than the animal-protein based diet, other factors could have potentially played a part in digestibility. The findings of this study would be validated and strengthened by repeated studies on the digestibility of other types of animal-protein and plant-protein based adult dog foods.

The original article, Apparent and true digestibility of macro and micro nutrients in adult maintenance dog foods containing either a majority of animal or vegetable proteins, is viewable in the Journal of Animal Science.

https://www.asas.org/taking-stock/blog-post/taking-stock/2020/10/19/interpretive-summary-apparent-and-true-digestibility-of-macro-and-micro-nutrients-in-adult-maintenance-dog-foods