# Comparative Evaluation of Nutrient Digestibility in Beagle Dogs of Different Life Stages

## TL;DR

This study shows how nutrient digestion in dogs changes with age, helping to inform better dietary strategies for puppies, adults, and seniors.

## Contribution

The study provides new empirical data on age-related differences in nutrient digestibility in Beagle dogs.

## Key findings

- Puppies had lower crude protein and essential amino acid digestibility compared to adults and seniors.
- Phosphorus digestibility was highest in puppies and decreased with age.
- Ether extract digestibility was significantly lower in puppies but highest in adults.

## Abstract

This study compared nutrient digestibility across the life stages of dogs fed an identical diet. The digestibility of some major nutrients differed with age. Puppies exhibited reduced digestibility of crude protein and essential amino acids, whereas adults showed the highest ether extract digestibility. Phosphorus digestibility was highest in puppies and declined with age, whereas calcium digestibility did not differ. The digestibility values in seniors were slightly lower than those in adults; however, this difference was not statistically significant. These results highlight life stage-related differences in nutrient utilization and provide a basis for tailored dietary strategies in companion dogs.

This study evaluated age-related changes in nutrient digestibility in dogs and examined the effects of physiological development and dietary composition on digestive efficiency. Twenty Beagle dogs were assigned to three groups: puppies (<1 year; n = 8), adults (3–4 years; n = 8), and seniors (10–11 years; n = 4). All animals were fed diets formulated to contain identical nutrient levels that met or exceeded the minimum recommended nutrient requirements established by the Association of American Feed Control Officials. The digestibility of dry matter (DM), crude protein (CP), ether extract (EE), nitrogen-free extract (NFE), calcium (Ca), phosphorus (P), and amino acids were compared among the groups. The results showed that NFE digestibility was significantly higher in puppies, whereas CP digestibility was lower than that in adults and seniors, likely due to immature digestive function. In addition, EE digestibility was significantly lower in puppies, whereas P digestibility decreased with age. No significant difference was observed in Ca digestibility. Amino acid digestibility is lower in puppies, particularly for essential amino acids such as lysine, isoleucine, histidine, and arginine. These results indicate that age-related differences in digestive physiology and protein source affect nutrient utilization, providing a basis for developing life stage-specific nutritional strategies for companion animals.